Re: [EVDL] EV Digest, Vol 76, Issue 31

2019-02-28 Thread Roger Stockton via EV
Lawrence Rhodes wrote:

>> I'm wondering how much capacity the capacitors are adding to the system,
>> as the voltage of the capacitors can never go below the sag voltage of
>> the LiIon cells under load, and can never go above the LiIon cells
>> voltage during regen.
> 
> 
> I am not sure this statement is correct.  I am counting on the caps to
> take higher voltage.
> If the regen statement is true maybe under regen the battery pack should
> be disconnected.  Lawrence Rhodes

It is correct: you are proposing connecting the battery and caps directly in 
parallel, therefore they must always be at (very nearly) the same voltage.

But, don't worry, this doesn't necessarily prevent them from achieving your 
goal.  You stated your goal is to try to keep the peak current seen by the 
battery below 90A despite peak loads of 100A.  When the load changes, current 
will divide between the caps and battery based on their impedance relative to 
each other.  That is, suddenly applying a load to the battery causes its 
voltage to sag (somewhat); however, as soon as it sags even a little, the lower 
impedance ("stiffer") cap bank supplies more of the load current, and so the 
battery sags a bit less (and supplies a bit less of the load) than it would 
without the caps.  The opposite occurs during regen: suddenly applying current 
to the battery causes its voltage to increase, and if it rises high enough the 
controller will reduce the regen current (hopefully).  With the caps in 
parallel, as soon as the battery voltage tries to rise even a bit, less of the 
current goes to the battery and more of it goes into the caps.  Less current 
into the battery results in a bit less voltage rise, so the peak battery 
voltage during regen tends not to spike as high as it would without the caps.

How much reduction in battery current is realized will depend upon how much 
lower impedance the caps are than the batteries.  The benefit will be more 
pronounced if the battery has significantly more impedance than the caps.

Cheers,

Roger.

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Re: [EVDL] Maxwell Supercap 16v modules could protect my expensive lithium batteries.

2019-02-27 Thread Roger Stockton via EV
Jay Summet wrote:

> I'm wondering how much capacity the capacitors are adding to the system,
> as the voltage of the capacitors can never go below the sag voltage of
> the LiIon cells under load, and can never go above the LiIon cells
> voltage during regen.
> 
> I'd love to see a comparison graph of the voltage of the system battery
> bank during a hard acceleration and a hard regen event both with and
> without the capacitors installed to see the voltage regulation effect.

Victor Tikhonov (of MetricMind) used a string of 2.7kF Maxwell supercaps (17F 
total) in parallel with the lithium pack in his CRX conversion, back in 2004.

Something Victor mentioned on the site for his conversion is the need to 
disconnect the string of caps from the battery during charge.

Unfortunately, the links in Victor's original message (quoted below) appear 
dead, however, his comments describing the results of his measurements are 
still informative.

> -Original Message-
> From: Victor Tikhonov [mailto:vtikh...@lsil.com]
> Sent: October-07-04 4:53 PM
> To: e...@listproc.sjsu.edu
> Subject: Does the passive balancing of uptracaps stack really works?
> 
> I've made a few measurements on the most easily accessible
> caps (last 10 caps in the series string) after couple of
> driving/charging cycles. Objective was to see if they are
> drifting apart far enough that the passive resistor based
> balancing cannot keep up with bringing them all back to order.
> 
> Looks like whatever initial voltages are settling at, they all
> go up and down at the same rate, so at the end of the day
> while overall average SOC is different, deltas between the same
> caps are still identical. Which tells me that for my circumstances
> making active balancing would be waste of effort.
> 
> Will see how well this keeps repeating in the long run.
> 
> http://www.metricmind.com/misc/ultracap.gif
> 
> In case you missed the link showing about 10x stiffness
> improvement using ultracaps, captured data screens are here:
> 
> http://www.metricmind.com/misc/test1.gif
> Left half - with caps, right half - without.
> (did few hard regens in the middle - to separate data points)
> 
> Zoomed in version:
> http://www.metricmind.com/misc/compare.gif
> 
> I'm noticing a side benefit I didn't think of before:
> no matter what the SOC of the battery is, combined
> with ultracaps it feels just as stiff at the end of
> discharge as full. This is because ultracaps have fixed
> internal resistance no matter how discharged they are.
> 
> When the pack getting tired, recharging caps from LiIons
> after accelerations getting slower, but by the time it is
> completed, the pack is as stiff for the next acceleration
> as the fresh one.
> 
>  From here (bottom plot) you can see how efficient
> my system happen to be (motor power out / batt power in):
> 
> http://www.metricmind.com/misc/eff.gif
> This is actually unrelated to the presence of the capacitors.
> 
> So far I'm very pleased with outcome of my setup. LiIons
> don't get much chance to see more than 30A out of them
> during quick accelerations, the same absorbing regen.
> The caps do all the work :-)
> 
> --
> Victor
> '91 ACRX - something different
>
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Re: [EVDL] EVSE.uk to ban pih> cheap onboard-3kWh-rechargers too-slow

2018-12-12 Thread Roger Stockton via EV
Willie via EV wrote:

> > https://www.autoexpress.co.uk/car-news/105449/ban-plug-in-hybrids-from
> > -ev-charging-bays-say-experts Ban plug-in hybrids from EV charging
> > bays, say experts 10 Dec, 2018  Tristan Shale-Hester
> 
> I was hoping some one would comment on this.  Can someone make sense of
> it for me?
> 
> They imply that 3kw level 2 charging interferes with 50kw level 3
> charging.  Of course, barring terrible parking space configurations,
> that is not possible in the USA.  Is it possible in UK?  Or Europe?

I'm guessing, but I think this situation is associated with the combined 
charging system (CCS) connector:



Basically, it is possible for a charging station to support either ordinary 
Level 2 (AC) charging or Level 3 (DC) charging with a single charge cable and 
paddle.  I don't know if there are EVSEs that support both, or if only EVSEs 
that support one or the other are available even though the same connector 
would appear on both types.

Assuming that a CCS EVSE supports both Level 2 (AC) and Level 3 (DC) charging, 
then any vehicle (not just PIH) that is only capable of Level 2 (AC) charging 
might be seen as interfering with another vehicle's ability to use the EVSE's 
Level 3 (DC) capability since the (single) charge cord is then unavailable. 

While I tend to agree that an EV needs access to an EVSE with greater priority 
than a PIH (or so-called 'extended-range EV' ;^), since the EV cannot move 
without charge while the PIH can, trying to restrict access based on vehicle 
type or charger capability seems like a slippery slope to start down.  Do I get 
to unplug your 3kW-charger Leaf and plug my car in because my 6kW charger is 
able to utilize more of the EVSE's capability?  Can I unplug your PIH to plug 
in my EV, because I *need* a charge to get home while you want one "just" to 
avoid running the ICE?  What if I unplug your Tesla because you've got tons of 
battery capacity while my Leaf's much smaller capacity battery means I rely on 
being able to add a bit of charge before heading home? ;^>

Cheers,

Roger.

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Re: [EVDL] poor 2011 Leaf performance

2018-12-06 Thread Roger Stockton via EV
Steve Heath wrote:

> The best mile/Kw I have got has been 180 and the worst is 230. Average
> is 190 and this measurement is based on coulomb counting over the
> distance.

I think you are meaning to state 180-230 Wh/mi?  180-230 mile/kWh would be 
extremely unusual efficiency for an on-road EV, and mile/kW just doesn’t make 
any sense ;^>

> If I use the capacity used based on voltage then it can get very silly.
> I was getting figures of 600-700 w/mile because the voltage vs soc is
> non linear. I could drive 25% of the range and the capacity would drop
> to 50%. This did not make sense so I stopped using them and fitted
> coulomb counters. I do use the voltage to predict low battery but the
> rest of the data is just a rough guide. The gauge does  look pretty on
> the dash though.

I understand your reasoning for not using battery voltage to estimate state of 
charge, but when you quote any efficiency values involving Wh or kWh (Wh/mi or 
mi/kWh), you are, of course, taking battery voltage into account because power 
depends upon both the battery voltage and current, and so, therefore, does 
energy in Wh or kWh.

Pure coulomb-counting will only give you energy usage in mi/Ah, which may be 
useful in the context of your own EV, but does not allow comparison to the 
usage of other EVs.

Cheers,

Roger.

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Re: [EVDL] AM radios dropped from plugins (RFI, EMI, +)> (go digital)

2018-11-09 Thread Roger Stockton via EV
Peri Hartman wrote:

> Hmm, maybe cost savings of putting a grounded shield around the motor
> and controller. For the AM radio, what could the cost be? $1.00?

Good point; perhaps the real cost savings isn't the radio itself, but that its 
absence allows them to cut corners (and cost) elsewhere on EMI measures?

That said, my conversion doesn't need shielded conductors or a shield around 
the controller in order for AM to be perfectly usable, so I'm not sure where 
they would cut costs such that they needed to eliminate AM capability to "hide" 
their cost saving measures?  Commercial EVs pretty much always have the 
controller in an aluminum enclosure, so it should be largely shielded for 
"free"; I doubt we'll see controllers in plastic boxes very soon ;^>

Cheers,

Roger.

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Re: [EVDL] AM radios dropped from plugins (RFI, EMI, +)> (go digital)

2018-11-09 Thread Roger Stockton via EV
Tom Keenan wrote:

> I have a 2013 Leaf, and the AM radio works fine. Same with my old 2005
> Prius.  I use the AM radio on a daily basis during my commute to work.
> Not sure if it is perhaps an issue with certain radio suppliers/car
> manufacturers?

I suspect it has more to do with the cost savings of not including AM 
capability (probably perceived to be relatively unused and therefore easily 
eliminated without much outcry) than any real technical issue.

AM works fine in my wife's 2016 Leaf and in my conversion; there really doesn't 
seem to be any reason for it not to work in any plugin, unless one doesn't want 
it to work...

Cheers,

Roger.

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Re: [EVDL] Has Tesla gone too far?

2018-09-22 Thread Roger Stockton via EV
paul dove wrote:

> 
> 
> Sent from my iPhone
> 
> > On Sep 22, 2018, at 11:28 AM, Haudy Kazemi via EV 
> wrote:
> >
> > Which models have SAE ports? The only adapter I know of is Chademo.

The linked article describes a dual-standard charge inlet that adds the Chinese 
GB connector for the China market only.  This is *not* an SAE charge inlet, and 
it is only available on Chinese market Teslas.

Roger.

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Re: [EVDL] Mom yanks kids from e-toy-suv w/ smoking pack before it flames

2018-08-17 Thread Roger Stockton via EV



> -Original Message-
> From: EV [mailto:ev-boun...@lists.evdl.org] On Behalf Of Lee Hart via EV
> Sent: August-16-18 9:51 PM
> To: Electric Vehicle Discussion List 
> Cc: Lee Hart 
> Subject: Re: [EVDL] Mom yanks kids from e-toy-suv w/ smoking pack before
> it flames
> 
> brucedp5 via EV wrote:
> > https://www.cbsnews.com/news/north-andover-massachusetts-michelle-kline-
> kids-electric-toy-car-bursts-into-flames-video/
> > Mother yanks 2 children from electric toy car before it's engulfed in
> flames
> 
> There's got to be more to the story.
> 
> It looks like one of the classic "Powerwheels" jeeps that have been sold
> for 20+ years.

In the article it is said to be a "SPORTrax Awesome XL", which does not appear 
to be a Powerwheels product.

It is described as 4WD, and is remote controllable (for parental override) as 
well as the normal occupant-controllable.

Perhaps most importantly, it requires 2 12-volt batteries (12V 10Ah per the 
product description; Powerwheels use a pair of 6-volt), and the batteries do 
*not* appear to be included!  So, it is entirely possible that the buyer of 
this toy installed inappropriate batteries:



Cheers,

Roger.
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Re: [EVDL] Charging load on the grid (NOT)

2018-07-30 Thread Roger Stockton via EV
Cor van de Water wrote:

> Another data point to consider:
> The *cheapest* (base tariff) rate of household electricity here in Silicon
> Valley has now been raised above $0.21 per kWh.
> If you go over your baseline (about 11 kWh/day) then price increases over
> 30c/kWh which almost everyone hits.
> So, the rate of financial savings here is about 3 times as fast as you
> calculated with 10c/kWh.

Just another reason that we need to avoid generalising a specific situation as 
being applicable in general ;^>

Here (British Columbia, Canada), our base rate is $0.0884/kWh for the first 
1350kWh over a 2-month billing cycle (about 22kWh/day).

Again, the point was not to argue whether the specific values in my example 
apply to everyone (or anyone ;^), but just to illustrate that communicating the 
financial benefit of saving energy is trickier to do.

Cheers,

Roger.

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Re: [EVDL] Charging load on the grid (NOT)

2018-07-30 Thread Roger Stockton via EV
Cor van de Water wrote:

> LED prices are much more competitive than you put in your calculation.
> Almost every LED that I see can be had for $5 or less.
> Best selling on Amazon is a good quality, non-dimming LED for $1.39 when
> you buy a 16 pack ($22.22 for the pack)

It was not my goal to try to shop for the best price for each type of bulb, but 
to use apples-to-apples in the sense that both bulbs being compared were from 
the same vendor (and were the same brand), so that even if the prices are not 
the best, they should both be similarly inflated.

I compared dimmable LED bulbs, which are a bit more costly than non-dimmables, 
since the halogen bulbs are dimmable, and so a non-dimmable LED bulb would be 
an unfair comparison as it could not be used to replace a halogen bulb in all 
cases.

Robert Bruninga wrote:

> >  halogen  $31.94/12;
> >  LED $107.88/12.
> 
> That's $9 each!
> Wow, not at my home depot.
> 60W(eq) LEDs in a package of 4 only cost $8 or $2 each at my home depot
> 75W(eq) maybe cost $3 each?
> This is a routine price, not a "sale"...
> But I think the utilities subsidize them somewhat.

Bear in mind that the prices I quoted are in Canadian dollars, and so will 
appear higher than US prices due to the exchange rate.  As I state above, the 
LEDs I chose to compare are dimmable ones, and so not necessarily the cheapest 
one can find.

Don't get too hung up on the exact numbers; the salient point here is that LEDs 
cost at least a bit more than the CFL or incandescent bulb you replace, and so 
it takes a while before they save enough energy to recover the initial purchase 
cost.  Only after that are the energy savings realised in a financial way.

Clearly, using the LEDs saves *energy* that then becomes available for the EV 
to use, but how much *money* is saved will depend upon the type of bulb 
replaced, the particular LED bulb used to replace it, how the bulb is used, and 
how long the bulb lasts before needing to be replaced again.  This just makes 
it difficult to communicate the advantage in a simple financial savings way, 
which is easier for most people to understand.

Cheers,

Roger.





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Re: [EVDL] Charging load on the grid (NOT)

2018-07-30 Thread Roger Stockton via EV
David Roden wrote:

> Incandescents that are used daily burn out fast, and get replaced with
> modern CF or LED retrofits.

My experience is that if you are in the habit of turning a light on when you 
enter a room and off when you leave, that CFLs will die *faster* than 
incandescents.  If you leave a CFL on continuously, it will last much longer 
than if it is switched on and off frequently.

I don't yet know if LED bulbs will outlast CFLs or incandscents when they are 
switched on and off frequently.  (See, for instance, 
.)

> For something like this argument to hit home and get them off their
> duffs, they have to able to nod and think, "Sure, that makes sense for
> us."
> Whether it's accurate or not, does "LEDs pay for the EV's energy" really
> do that, do you think?

When I was trying to convince my strata corporation to allow me to charge my EV 
(a conversion), what I found was that many people cannot understand the amount 
of energy that an EV consumes.  They see an extremely large "appliance" and 
assume that it will consume so much electricity that the lights in the building 
will dim when it is plugged in, and the electric bill will go through the roof, 
etc.

So, I think the challenge will be in making them understand/appreciate that the 
energy savings associated with a few lightbulbs can really save enough energy 
to allow an EV to drive some miles each day.

As to the "accurate or not", I think it is not trivial to get an accurate idea 
of the possible savings.  Due to the difficulty buying household incandescents 
now, I tried a couple of apples-to-apples comparisons using Home Depot 
(Canada)'s online catalog:

50W GU10 halogen vs 5W LED:

  - halogen $15.97/6, so $31.94/12; LED $107.88/12.
  - LEDs cost $75.94 more; at $0.10/kWh, this is the cost of
759.4kWh of electricity
  - LEDs save 540W/h of use; so it will take 1406.29h, or 281.25 days
(0.77yr) at 5h/day with all 12 LEDs on before any saved electricity
is available for the EV.
  - after the breakeven point, each LED bulb used 5h/day will save 225Wh/day,
or about 1mi of range

23W CFL vs 14W LED (both 100W equivalent):

  - CFL $15.97/4, LED $12.97/2, so $25.94/4
  - LEDs cost $9.97 more; at $0.10/kWh, this is the cost of 99.7kWh
of electricity
  - LEDs save 36W/h of use; so it will take 2769.4h, or 553.8 days (1.5yr)
at 5h/day with all 4 LEDs on before any saved electricity is available
for the EV.
  - after the breakeven point, each LED bulb used 5h/day will save 45Wh/day,
or about 1/5mi of range

While it is fairly unarguable that *any* amount of electricity saved in our 
everyday non-EV use lives will allow us to drive an EV *some* distance without 
increasing our utility bill, I think it is still unclear that there is an 
economic benefit, which is unfortunate since more people understand dollars 
than watt-hours or miles of range ;^>

Cheers,

Roger.
  
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Re: [EVDL] Reposting, Still Need Help, 86 Year Old Uncle Still TryingAfter 34 Years to Get Bucket List GE EV1-B Based EV Car Running

2018-07-26 Thread Roger Stockton via EV
Matt Awesome wrote:

> Wait, I had this backwards. I thought we *were* discussing the EV-1
> vehicle, not the forklift controller.

Nope; it is confusing at first glance, but the EV-1 *car* was a Chevy, while 
the EV-1 *controller* is a GE product ;^>

> If we're talking about the forklift controller I can help! I stripped
> mine down to the bare minimum required to make it run.
>
> Here is a link to an album, where you should be able to click on
> individual high-res pictures: https://imgur.com/a/Y560sqp

The GE EV-1 SCR controller is quite similar to yours, but the SCR controller in 
your pictures is *not* and EV-1 (and possibly not a GE product ;^).  The 
drawings appear to identify it as a "STD. K70C M500 SCR", but Google isn't any 
help figuring out if this is an earlier GE model or not.

The person seeking help has a bit different situation than you or I (I also 
have an EV with a GE EV-1 controller in it), since he is electrically reversing 
the motor and so cannot simply eliminate the directional switch(es) and 
contactors like we did.

Cheers,

Roger.


> 
> Basically you can ignore almost everything and just gut it right down
> to its essentials to get the motor to run.
> 
> After cutting out all excess stuff out, you're left with some pretty
> minimal connections to make:
> - The motor connects to positive.
> - One motor field connects to one motor armature, doens't matter which
> for testing, it just sets direction.
> - The motor connects to the speed controller.
> - The speed controller connects to negative.
> - The foot pedal potentiometer connects to the controller (pin 29?)
> - The foot pedal "power on" switch connects to a contactor, or a dummy
> load to fool it to thinking there's a contactor there. (pin 41,
> through dummy load to positive?)
> 
> I think that's all, there might be a wire or two I'm missing but, there
> you go.
> 
> Does that help? I don't have it in front of me and I'm quite rusty
> since it was a year ago that I figured this out, got it working, and
> then abandoned it for another controller... but I'm pretty sure I
> could walk you through it if need be.
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Re: [EVDL] Reposting, Still Need Help, 86 Year Old Uncle Still TryingAfter 34 Years to Get Bucket List GE EV1-B Based EV Car Running

2018-07-25 Thread Roger Stockton via EV
Cor van de Water wrote:

> Not that I remember that this was a requirement for the GE EV1
> controller.
> That would also not have worked for my controller, [...]

Cor, while your GE controller might well have had similar (or identical) switch 
input requirements as the GE EV-1 SCR controller in question, it is worth 
noting that your controller was *not* an EV-1.  The EV-1 is an older, SCR, 
controller, while yours was a newer GE IGBT controller (I suspect one of the 
EVT-xxx models, where the 'T' appears to indicate "transistor", either MOSFET 
or IGBT).

This page provides pictures and manuals for several models of GE controllers 
(EV-1, EV-10, EV-100, etc.):



The EV-1 logic does require several switches to open/close in proper sequence 
(and sometimes timing) to enable operation when wired as originally intended 
(for lift truck applications where a key, seat, brake, and direction switch 
were all normally present), but when installed in an on-road EV (especially 
with a transmission), it is common practice to wire the controller to defeat 
the built-in safeties associated with these inputs.

Cheers,

Roger.
 
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Re: [EVDL] K BC20 96 volt charger replacement?

2017-09-28 Thread Roger Stockton via EV
brucedp5 wrote:

> 12VDC deep-cycle batteries do not last as long as 6V golf/traction
> batteries. The latter have thicker plates= more lead.

The latter part of this statement is no longer necessarily true; as the golf 
industry moved to 12V floodeds for their 48V cars, 12V flooded batteries became 
available that have the same plates as their 6V (and 8V) brethren (e.g. Trojan 
T1275 and US12VXC models).

> The Zivan k & ng series chargers evolved into the series Elcon sells.

This is incorrect; the Chinese-origin PFC chargers that Elcon sells began as 
clones of the Delta-Q charger and evolved from there.  It is a bit confusing 
because Elcon was previously representing the Zivan product line, and so some 
mistakenly associate the Elcon-branded PFC chargers with Zivan.

Note that the Elcon-branded PFC chargers will not have *any* regulatory 
approvals; any "CE" mark on them, if examined closely, will be found not to be 
the European (self-declaration, not 3rd-party inspected) regulatory mark, but a 
remarkably similar marking of no related meaning that is specific to China.  
This is one reason that the Delta-Q products are somewhat more expensive; 
internally they use approved insulation systems, etc. and are tested to comply 
with North American (and European and various other locale's) EMI, EMC, and 
safety agency standards.

> The advantage is both of these charger brands are dual input voltage (they
> run off either 120 or 240VAC). Which means, Mary could continue to charge
> off a 120VAC outlet as she had in the past, but at some point she could
> buy an upgrade j1772 kit from an EV component re-seller (there are a few
> on the evdl) that would allow Mary to charge her MG EV off the 240VAC a
> public EVSE would provide.

Agreed; this is a definite reason to upgrade to a more modern, universal input 
charger model.

Note that "dual voltage" chargers are probably best avoided, as this usually 
implies a (non-PFC) charger whose input automatically switches between a "120V" 
and "240V" setting based on the input line voltage, or one that must be 
manually switched between settings the by the user each time they plug into a 
different voltage source.

Public (J1772 level 2) charging stations will be either 208V aor 240V, while an 
overnight charge at home will usually be from a 120V outlet; it could be fatal 
to a dual input charger if one forgot to switch it to the appropriate input 
voltage range before plugging in.

> An alternative to the alternative ...
> Way in the past, an evdl member poo-poo's my use of several individual
> 12VDC chargers to charge my pack. Stating that it increases the probability
> of a charger failure. Later, other EVrs installed individual 12V chargers
> and had good success (so poo-poo to the poo-poo'r).
> 
> 12VDC chargers found on ebay are incredibility cheap (almost those away if
> they fail, cheap).

I won't poo-poo the idea, but I don't recommend the use of multiple chargers 
spanning a pack unless there really is no viable alternative.  Aside from the 
reliability issue, the reality is that all commonly available 'fuel'/Ah/SOC 
gauges look only at overall pack voltage and overall pack current, and so can 
only ever account for the charge current/Ah of *one* of the N chargers spanning 
the pack.

What invariably happens is that each charger delivers somewhat different 
current, and so unless one waits until *every* charger has completed, they will 
drive off with each section of their pack at a different SOC, and will only 
know the SOC of the single section that the gauge was monitoring the current 
for.  The worst case is that one of the chargers fails (fuse opens, or wiring 
fault, or simply derates thermally because it is in a hot location, etc.) and 
the user discovers this only when that section of the pack runs flat (or 
reverses...) while they are driving.

> I would order 8 of the 10A US models. The outputs would go across each
> battery (one 10 12V charger for battery), and all the AC plugs would be
> wired into one line, so you only have to plug in one 102VAC cord (same as
> before).

Be careful here: it is quite easy to end up with a bank of chargers whose input 
power requirements exceed what a common outlet can provide.  At 2.4V/cell and 
10A, each of these chargers would be outputting 144W; 1152W for 8 of them.  
They might only be 80% efficient, which brings the input power up to 1440W.  
This is right at the 12A that a 15A-rated 120V circuit can provide *IF* the 
voltage at the charger input is 120V.  Usually, the outlet voltage is lower, 
and so the current drawn by the chargers will be higher.  If they are not PFC, 
then the peak input current will be even higher than that estimated just by the 
power requirements.

A bank of 8 of these ~might~ just squeak by on a 15A 120V circuit, but a 20A 
120V circuit is probably a better choice.  Opportunity charging on a 15A 
circuit would definitely be risky without knowing what else might be on the 
same 

Re: [EVDL] Slow due to 96V pack?

2017-09-14 Thread Roger Stockton via EV
paul dove wrote:

> There is no voltage adjustment on input voltage in any motor controller I
> ever used.

This discussion specifically concerns a vehicle using a Zilla motor controller; 
from the Z1K specsheet:

"Other features include programmable motor voltage and current limits, 
programmable battery voltage and current limits, adjustable low battery voltage 
protection and an additional low battery indicator output."

> It may have a low voltage cutoff circuit but that just shuts down the
> output in the event the battery falls below 72volts thus the
> controller would not be working if the voltage was 96-72 = 24volts.

Even this simple case would achieve the *same* behaviour: the controller would 
PWM "willy-nilly" until the input voltage sagged below the minimum input 
threshold, then it go to 0% duty.  As soon as it went to 0% duty, the load on 
the battery would decrease, and the input voltage would rise slightly above the 
minimum threshold, and the controller would resume PWMing.

Resuming the load would sag the input voltage below the threshold again, and 
the cycle would repeat such that the input voltage is regulated in a sawtooth 
manner at the minimum voltage.

Cheers,

Roger.


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Re: [EVDL] Slow due to 96V pack?

2017-09-14 Thread Roger Stockton via EV
paul dove wrote:

> That made no sense to me but a DC motor controller takes the input voltage
> to power mosfets or igbts which switch the power on and off with a pwm
> signal to get the desired output to drive a motor. It has no knowledge of
> the battery impedance.

The controller does not have, or need, knowledge the battery impedance; this is 
simply Ohms Law at work.

The controller PWMs the power from the battery, and the duty cycle of the PWM 
can be varied to limit whatever parameter the controller logic cares about at 
any given time: input voltage, input current, output voltage, or output current.

Since the battery has a finite, non-zero internal impedance, its terminal 
voltage will sag as current is drawn from it.  If the motor controller enforces 
a minimum input (battery) voltage (as does the controller in question), then 
its logic will vary/limit the PWM duty cycle to prevent the voltage at the 
input of the controller from falling below the target level.

Since the controller logic will limit/vary the input current to prevent the 
input voltage from falling below the threshold, then the maximum voltage 
difference across the battery internal resistance is the open circuit battery 
voltage minus the minimum input voltage limit of the controller: 96V - 72V = 
24V, in this example.

The controller does not know what the internal impedance of the battery is, but 
Ohms Law still applies to limit the maximum current from the battery to 
*whatever* value results in 24V drop across the internal resistance: 24V / 0.08 
ohms = 300A in this example.

*IF* the sophisticated controller were replaced with a simple contactor 
controller, then if the contactor controller allowed the entire 96V battery to 
be connected directly to a stalled motor (~0 ohms), the voltage drop across the 
battery internal resistance would ~approach~ 96V - 0V = 96V, and the peak 
current into the motor would approach 96V / 0.08 ohms = 1200A.

Hope this helps,

Roger.

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Re: [EVDL] Slow due to 96V pack?

2017-09-13 Thread Roger Stockton via EV
paul dove wrote:

> You said:Here's my guess: A 6v golf cart battery has an internal
> resistance of about 5 milliohms (0.005 ohms). A 96v pack has 16 of them;
> so the resistance is 0.005 x 16 = 0.08 ohms. Let's say the Zilla limits
> voltage to 72v (i.e. it won't pull the pack below 72v). Then the most
> current you can get is I = V/R = (96v-72v) / 0.08 ohms) = 300 amps.
> **It is either going to be 96v/0.08, 72v/0.08, or somewhere in between.
> The voltage won't be 24/0.08 at any time.So, somewhere between 1200 and
> 900 amps.

You are (almost) correct only if you *short* the battery terminals, so that the 
voltage on the load side of the internal resistance is 0V.

This is *not* the case with a controller that enforces a low voltage cutoff, 
such as the 72V value in the example:


 0.08 ohm
Internal R 
 +---/\/\/\/\--oo--+
 | |
   --+-- ideal / 72V 
---  96V   \ minimum load
   - battery   / voltage
-+-\
 | |
 +-oo--+ 

The controller effectively regulates the voltage on the load side of the 
battery internal resistance such that the voltage difference across the 
internal resistance will indeed be approximately as Lee states.  And the 
maximum battery current that *this* load can draw will be on the order of 
(96-72)/0.08=300A.

Cheers,

Roger.



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Re: [EVDL] Electric vehicle subsidies: expensive and ineffective?

2017-08-03 Thread Roger Stockton via EV
Dan Baker wrote:

> Would anyone care to comment on this?  Agree or disagree?  Is it oil
> funded
> FUD? I live in Nova Scotia, Canada, one of the have-not provinces for EV
> rebates.  I can affirm that without rebates EV car sales here are pretty
> well nonexistent, most dealers here carry very little EV stock and the
> charging infrastructure is well behind provinces that do offer rebates.  I
> see other  media outlets and even local environmental groups regularly
> quoting this article too.  Sounds like my province will never get an
> incentive with this type of media :-(

The article questions the effectiveness of EV subsidies as a means of reducing 
carbon emissions, which I can't really comment on (other than to say that I'm 
not sure that carbon trading (the approach favoured by the authors) does 
*anything* to ~reduce~ carbon emissions: all it offers is a mechanism by which 
a country may emit more CO2 than it would otherwise be allowed by purchasing 
'credits' to emit CO2 from a country that is emitting less than it is allowed).

However, it does appear to me that EV subsidies are a ~very~ effective way to 
increase EV adoption.  I'm in Vancouver, and while the BC subsidies are not as 
generous as those in ON and PQ, EVs (mostly Leafs and Tesla, though iMiev, 
Smart ED, Bolt, Kia Soul EV, and even the odd Focus EV can be seen) are quite a 
common sight here.  The incentives also encourage purchase of PHEVs, so Chevy 
Volts are also not an uncommon sight.

Cheers,

Roger.

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Re: [EVDL] ? Is this really a Smart Fortwo ED EV that burnt to a crisp ?

2017-07-12 Thread Roger Stockton via EV
EVDL Administrator wrote:

> A lot of people have shown an interest in discussing the origins of the
> fire here, but I haven't seen any posts yet addressing Bruce's question
> -- was this really a Smart?
> 
> Bruce provided links that show a Smart chassis.  The burnt-out skeleton in
> the photos resembles it.  However, there are also some differences.

There are 3 (or 4?) generations of Smart ED, so no guarantee that the links 
Bruce provided show chassis that are for the same generation as the burnt 
vehicle (stated to be a 2017 Smart ED).

If you look up pictures of what an unburned 2017 ED looks like

e.g. 

it is clear that the front end/grill has been redesigned to be more 
"Mini-esque", and it is not unreasonable that there might be some different 
(from prior generations) support structure behind the bodywork.

Wikipedia () has some 
pictures of various generations of Smart ED, and also states:

"The third-generation Smart electric drive was unveiled at the September 2011 
Frankfurt Motor Show.[5] Key differences with the second-generation model 
include a more powerful electric motor, which improves acceleration and top 
speed; a new lithium-ion battery pack that will allow to increase the range to 
140 kilometres (87 mi) and an option for quick-charge will be available; and 
other features include an enlarged grille opening, stylish LED daytime running 
lights, wider door sills, some minor modifications to the rear, fully automatic 
air conditioning with pollen filter and pre-air conditioning."

Given that the third generation has different front end/grill styling, wider 
door sills, and "minor modifications to the rear", it seems important to 
compare the burned vehicle remains to pictures of only same generation Smarts.

Cheers,

Roger.

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Re: [EVDL] ? Is this really a Smart Fortwo ED EV that burnt to acrisp ?

2017-07-11 Thread Roger Stockton via EV
Cor van de Water wrote:

> Remember that an EVSE has a relay interrupting the 240V supply.
> As I related before, any wire that is damaged or improperly tightened
> can burn, even if not overloaded for the spec of the wire.
> If the EVSE is not frequently used, there is the risk of corrosion of
> the relay contacts, adding to the resistance and easily causing
> overheating of the relay or even starting a fire.

Even if this were the case, it would result in the EVSE itself perhaps catching 
fire, or otherwise failing and interrupting AC power to the car's on-board 
charger.

It is difficult to imagine a scenario where the wall-mounted EVSE visible in 
the pictures could burn with such intensity as to catch a nearby vehicle on 
fire in this way.

I find it especially difficult to believe given that some of the photos clearly 
show the charge cord still attached to the vehicle, and aside for the few feet 
immediately at the car end of the cord, the cord itself appears undamaged.

Cheers,

Roger.

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Re: [EVDL] Most efficient hub motor for 20" wheel

2017-05-30 Thread Roger Stockton via EV
Lee Hart wrote:

> My Bike-E has a 7-speed rear hub, and of course a very long chain. My
> thought was to mount the motor under the seat, with a freewheel
> sprocket to the chain.
> That way, it gets the benefit of the gearing. The freewheel means you're
> not spinning the motor when it's not being used while pedaling.

What you describe is similar to how we electrified Rob Cameron's Bike-E:



The main difference is that you propose using a freewheel to allow pedaling 
without spinning the motor (which is quite useful when the batteries run out), 
while our approach put a freewheel and an additional 7-speed cassette between 
the pedals and the motor shaft.

The freewheel allowed the cyclist's feet to remain stationary on the pedals 
while cruising under electric power (rather than being forced to spin at a 
speed determined by the electric motor), and the 7-speed cassette between the 
pedals and motor shaft allows the cyclist to provide assist at any cruising 
speed without having to pedal uncomfortably fast or slow.

A decided benefit of placing the motor mid-ship like this is that it breaks the 
very long stock chain run into two shorter, more manageable runs ;^>

Cheers,

Roger.

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Re: [EVDL] Adapting L1 to 14-50 receptacle

2017-02-28 Thread Roger Stockton via EV
Chris Tromley wrote:

> So here's my question.  A 14-50 has a neutral, so I'm pretty sure I can
> adapt my brick to it by simply tapping one leg of the 240 V.  Is there
> anything subtle that I'm missing?  Like if there are a bunch of these
> outlets fed by a single panel and I pull 3 kW off one leg of one, is that
> an issue?  Anything else?

You should be fine using an adapter to take one hot, neutral, and earth ground 
from the 14-50 to a 5-15 receptacle to plug your L1 opportunity charge cord 
into.

However, you will *not* pull 3kW from anything ;^>

Your L1 charge cord is 120V input only, and almost certainly is configured 
internally to generate a pilot signal to the EV that tells it not to draw more 
than the 12A continuous rating of a 5-15 outlet (assuming your charge cord has 
a NEMA 5-15 plug on the wall end, and has not been hacked).

So, as long as you only feed it 120VAC you should not fry anything inside of 
it, and unless it has been hacked to generate a pilot signal for a higher 
current, your EV will not draw more than 12A from the wall when you use this 
charge cord, no matter what the capacity of the circuit you plug into.

Hope this helps,

Roger.

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Re: [EVDL] What is a compliance car? : ... Volt/Prius ...

2017-01-11 Thread Roger Stockton via EV
Robert Bruninga wrote:

> Sorry for your bother... But there is a huge difference and the name
> differentiation is good.  Since the Chevy Volt has the longest EV range of
> every one of the 15 plug-in hybrids now on the market it diserves a very
> definite distinctive nomenclature.

The distinction between whether a vehicle is electric or a plug-in hybrid has 
nothing to do with how much more or less pure electric range it has than other 
vehicles of the same configuration.  The Volt, just as any of the other plug-in 
hybrids, has two fuel/energy sources: an electrical outlet and a gas pump.

The name differentiation is *bad* as it confuses buyers into thinking that the 
Volt is something other than a plug-in hybrid when many people are already 
confused between the difference between a hybrid and an electric car.  The only 
purpose it serves is to allow Chevy to pretend that the Volt is in a class of 
its own.

The 2017 Prius Prime offers 25mi all-electric range vs the first generation 
Volt's 35mi, yet one is described as a plug-in hybrid while the other is an 
"extended range electric vehicle"?  Many of us have (or have had) pure electric 
conversions with less than 25mi range, but they were (are!) still 
unquestionably EVs; is it helpful to anyone to invent a new vehicle class to 
differentiate shorter-range EVs from all other EVs?  I certainly don't think 
so.  

> The Volt on the other hand is a 60 mile daily commuter EV to-and-from
> which is as much as triple all the other ones and carries along a gas
> engine if needed to extend the range on a day when a long trip comes up
> that is unscheduled.
> 
> Big difference.

Big difference between a Volt and an electric car, indeed!  My sister was quite 
disappointed to find that her first generation Volt would *not* allow her to 
make her short commute on battery power alone in winter, despite the car being 
garaged each night.  Very unlike an EV, this vehicle insists upon running the 
ICE for much or all of her commute in cold weather despite the battery being 
fully charged and having more than enough range the trip in pure electric mode. 

IT is NOT an electric vehicle with an on-board range-extender (that one can 
choose to use or not), which is what one might reasonably expect based on the 
'extended range electric vehicle' classification; it is a plug-in hybrid that 
happens to have the greatest all-electric range of the present offerings.

I like the Volt, but don't see its greater range justifying invention of a new 
vehicle classification (with it as the sole member) any more than it would make 
sense to invent new vehicle classes for the EV with the longest range or the 
ICE vehicle with the longest range to allow their manufacturers to pretend that 
their vehicle is in a different class from all others.

Cheers,

Roger.


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Re: [EVDL] What is a compliance car? : ... Bolt named top car ...

2017-01-11 Thread Roger Stockton via EV
brucedp5 wrote:

> So, the less informed as Roger (people in the public, EVnoobs), would hear
> the phrase 'compliance car' without initially & truly understanding what
> it means, & just surmise (pick-up) that it is a not a positive thing. I
> would hope that those EVnoobs would later do the diligence (the proper
> research work to know what the actual definition of 'compliance car' is
> as well as Roger knows).

I take your point, Bruce, however, I suspect that the sad reality is that the 
general public has no idea what 'compliance car' means, including not knowing 
if it is a good or bad thing.

Regardless of what the uninformed masses might ~think~ such a term means, I 
would hope that we, in a forum such, as this would do our part to use the term 
properly and do our part to educate others in the correct meaning and usage of 
the term, just as we do with terms such as EV, BEV, PHEV, HEV, etc.

Just as it bothers me to no end each time I see the Chevy Volt referred to as 
an 'extended range EV' while the plug-in Prius remains (correctly!) classified 
as a hybrid, it bothers me to see people in this forum improperly use the term 
'compliance car' as a derogatory reference to any OEM EV offering that, in 
their opinion, represents something less than the best that the OEM is (or, in 
their opinion, should be) capable of offering.

Cheers,

Roger.

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Re: [EVDL] What is a compliance car? : ... Bolt named top car ...

2017-01-11 Thread Roger Stockton via EV
paul dove wrote:
 
> Quebec becomes the first Canadian province and 11th North American market,
> after 10 US states, to adopt a ZEV mandate.

Just as California does not constitute the entire American market, Quebec is 
not the entire Canadian market.

The Bolt is offered for sale in other Canadian provinces as well as in Quebec.

Cheers,

Roger.
 
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Re: [EVDL] What is a compliance car? : ... Bolt named top car ...

2017-01-11 Thread Roger Stockton via EV
brucedp5 wrote:

> That post and its responses are really about what 'we each' think what a
> 'compliance car' is.
> 
> I had this thought over a week ago when a news item tried to say the Bolt
> was not a compliance car based on how many EVs GM 'had to' produce vs how
> many more GM said they were going to make.
> 
> I know this topic could open a 'can of worms', but I think the definition
> of compliance car needs to be re-evaluated. What was a compliance car in
> the 1990's and 2000's, is much different than today.

I disagree.  I think that 'compliance' is a well-defined and unambiguous term 
that refers specifically to *complying* with a ZEV mandate such as CARB's to 
the minimum extent possible.

A compliance car would therefore only be offered where required to *comply* 
with such a mandate, and even in these areas might or might not be available 
for purchase.

Any vehicle offered for sale where not *required* to satisfy some regulation or 
mandate *cannot* be considered to be a compliance car, regardless of how 
competitive or desirable any individual might consider it relative to other 
available vehicles.

I think attempts to redefine or broaden the definition of the term to include 
vehicles that are offered for sale even where not required to comply with such 
mandates simply because an individual disagrees with the manufacturer's design 
choices or such is simply a case of those people who insist upon seeing the 
glass as half empty rather than half full and need to find something to 
complain about even as OEM EVs [slowly] become more readily available.

Cheers,

Roger.

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Re: [EVDL] Chevy Bolt named top car in N. America

2017-01-10 Thread Roger Stockton via EV
Dannyterhaar wrote:

> > And despite the fact that GM specifically said this was a compliance car
> > and had no intention of selling this in other states.
> >
> 
> Can you point me to a public posting of GM where they announced that ?
> I really tried to find it , but it's not popping up in google or other
> search engines for me.

I think the fact that the Bolt is available in Canada pretty much debunks any 
claim that GM intends[ed] it to be only a compliance car:



Cheers,

Roger.

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Re: [EVDL] Cheap L2 charging in parking places: Bolt EV'sIn Production

2016-11-09 Thread Roger Stockton via EV
ROBERT via EV wrote:

> Roger, let me try to clarify my concern.  A person buys a third party
> J1772 to NEMA adapter (made in China and made cheap).  The adapter has a
> NEMA rated 20A plug.  The adapter does not produce a modified pilot
> signal.

Just to be clear, the adapter does not (*cannot*) produce a modified pilot 
signal since the NEMA outlet has no provision for a pilot signal connection and 
the charger that plugs into the NEMA outlet does not require a pilot signal.  
The pilot signal *from* the J1772 EVSE is one-way only; that is, it is 
generated by the EVSE to inform the load of the maximum current that may be 
drawn *at that particular time* (i.e. while the EVSE may be capable of up to 
50A, it is possible for it to limit the current available to the load to any 
value less than this at any time).  There is no way for a J1772 charger or 
adapter connected to the EVSE to tell the EVSE to reduce the maximum available 
current.

> I take the cord and plug from the EVSE that is rated at 50A and
> plug into the adapter.  I take the 20A coil and plug from the charger in
> my converted car and plug into the adapter.  The charger will not draw
> more than 20A from the EVSE.  This is OK load wise because the EVSE can
> output 50A.  However, it is an unsafe circuit.  I have connected a 50A
> rated source to a 20A circuit with no interconnecting protection
> device.

I understand your concern with this configuration now.  I agree that the EVSE 
breaker will not provide adequate protection for a lower current rated 
J1772-to-NEMA adapter connected between the EVSE and the load (charger).  Note 
that this scenario is irrelevant in the situation where a NEMA outlet is 
provided at each parking spot as the charging infrastructure (which is what was 
proposed).

Note also that any charger with any safety agency (CSA, UL, etc.) listing 
*will* have a protection device at its input appropriately rated to protect it. 
 In this case the safety concern reduces to a user who tries to use an adapter 
that is under-rated for their charger (but still does not apply to the 
situation of a NEMA outlet charging infrastructure).
 
> Lets go the other direction.  I have a NEMA to J1772 adapter
> with no pilot signal.

This situation is *not* possible.  The reason you have a NEMA to J1772 adapter 
is to provide a J1772 connection to the charger, and the J1772 charger 
*requires* a pilot signal from the EVSE ("adapter", in this case).  The adapter 
*must* provide a pilot signal, the only question is if it provides a pilot 
signal that is appropriate for the rating of the NEMA outlet/circuit that it is 
plugged into.

> If the cable from the adapter is plugged into a car
> with a 50A charger, the circuit breaker will trip

No.  Since the J1772 charger requires a pilot signal, and the EVSE/adapter must 
provide one, the 50A rated charger will draw no more than the amount of current 
signalled by the pilot signal.  In the absence of a pilot signal, the charger 
will not draw *any* current.

The only safety concern when using a NEMA to J1772 adapter is that the adapter 
might generate a pilot signal that allows the charger to draw more current than 
the NEMA outlet/circuit it is plugged into is rated for.

This should not occur for any competently designed adapter.  As I described in 
my prior post, if a 120V NEMA to J1772 opportunity charge cord (adapter) has a 
5-15P NEMA plug at the wall end, then it "knows" that no matter what the supply 
circuit it is powered from might be rated for (i.e. 15A or 20A), it cannot 
allow the load to draw more than 12A since its own connector is only rated for 
15A (and such a circuit is limited to 12A max continuous loading).  If it has a 
5-20P NEMA plug at the wall end, then it "knows" that it can allow the load to 
draw up to 16A since its connector (and wiring) are rated for 20A and it can 
only be plugged into a receptacle/circuit rated for 20A.

In the event of use of an incompetently or unsafely designed adapter that 
generates a pilot signal allowing the charger to draw more current than the 
NEMA outlet it is powered from can safely deliver, the protection device 
between the supply and the NEMA outlet will trip and safely protect all 
connected devices.

I think that there is actually very little safety concern with a NEMA outlet 
charging infrastructure since the vast majority of people using NEMA to J1772 
adapters will be owners of OEM EVs and using the OEM opportunity charge cord 
provided by the OEM (i.e. competently designed adapters).

The main advantage of the NEMA outlet infrastructure, IMO, is that there are no 
charge cords left at each parking stall to be vandalised or stolen, however, 
the big disadvantage is that the vast majority (is anybody still building 
conversions?) of EVs that will use the charging infrastructure *don't* have 
NEMA connectors, but rather J1772 charge inlets.  So, each EV must carry around 
a NEMA to J1772 opportunity charge cord/adapter to 

Re: [EVDL] Cheap L2 charging in parking places: Bolt EV'sIn Production

2016-11-08 Thread Roger Stockton via EV
ROBERT via EV wrote:

> Again I must correct myself.  I looked back at the J1772 standard and some
> past work that I did.  An EVSE outputs a 1KHz square wave.  The duty cycle
> of this wave informs the the vehicle of the maximum amperage that the EVSE
> can supply (rated current).  The vehicle is responsible for not drawings a
> current greater than the EVSE rating.

Yes.

> All lower amperage adapters must
> limit this duty cycle to the rating of the adapter.  As an example.  If
> the EVSE is rated at 50 amps and the adapter is only rated for 20A, the
> adapter must adjust the duty cycle.

This is where you lose me.  If the EVSE is rated for 50A, then it generates a 
pilot signal that informs the vehicle/charger that it can draw up to this 
amount.  There is no need or purpose for an adapter between the EVSE and a 
vehicle unless the vehicle does not have a J1772 inlet.  If the vehicle doesn't 
have a J1772 inlet, then it also doesn't need (or understand) the J1772 pilot 
signal and so there is no need for an adapter to generate a pilot signal 
limiting the vehicle to a lower current than the EVSE is capable of providing.

> It is possible to design a 20A
> adapter with a switch and a resistor that does not modify the duty cycle
> from the EVSE.

Yes, and this adapter is used to convert a J1772 EVSE *into* a NEMA receptacle 
so that a non-J1772 compliant EV/charger may be plugged into a public charging 
station.

This is exactly the opposite of what would be required or used if NEMA 
receptacles were provided at each charging stall.  Most of us with conversion 
EVs have chargers that can plug directly into a NEMA outlet, and would not need 
an adapter more sophisticated than an extension cord.

Those of us with production EVs (other than Teslas, perhaps) will have J1772 
inlets and will need to use our J1772 "opportunity charge" cords; these are 
effectively "smart" extension cords with a NEMA plug on the wall end, a J1772 
charge paddle on the vehicle end, and a small EVSE in between that provides the 
appropriate pilot signal for the vehicle/charger.  If the NEMA plug on the wall 
end of the opportunity charge cord is a NEMA 5-15P, then the pilot signal 
should (must!) tell the charger not to draw more than 12A.  If the cord has a 
NEMA 5-20P plug, then the pilot signal can allow the charger to draw up to 16A 
(since this plug can only mate with a receptacle on a 20A rated circuit).

Even if the J1772 opportunity charge cord were to tell the charger it is OK to 
draw more current than the NEMA receptacle and circuit are rated for, there 
should be no safety issue: the NEMA receptacle and its associated supply wiring 
will be protected by an appropriately rated breaker and the breaker will simply 
open.

Cheers,

Roger.

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Re: [EVDL] Cheap L2 charging in parking places: Bolt EV'sIn Production

2016-11-08 Thread Roger Stockton via EV
ROBERT via EV wrote:

> How many of these adapters are approved by the vehicle manufacturer and
> how many are UL listed?

I would expect that every J1772 opportunity charge cord ("adapter") provided by 
a vehicle OEM will be UL listed and is clearly approved by that vehicle OEM for 
use with their vehicle(s).

> In addition, I know of companies that are selling
> adapters that do not issue a pilot signal (square wave).  The adapters
> only have a switch that show that a vehicle is connected.

This sort of adapter would be used by a non-OEM EV to charge *from* a J1772 
EVSE (such as a public Level 2 charging station).  A J1772-compliant EV will 
not charge unless the EVSE/adapter provides a valid pilot signal, however, a 
J1772-compliant EVSE (charging station) *will* provide AC to a non-J1772 
compliant EV/charger as long as the adapter loads the EVSE pilot signal 
appropriately.

Cheers,

Roger.

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Re: [EVDL] Cheap L2 charging in parking places: Bolt EV'sIn Production

2016-11-08 Thread Roger Stockton via EV
ROBERT via EV wrote:

> (1) How does a vehicle with a J1772 connector know the rating of the NEMA
> outlet?

The portable J1772 EVSE charging cord/adapter tells the vehicle via the pilot 
signal how much AC current may be drawn.  A 120V J1772 cord will almost 
certainly tell the vehicle not to draw more than 12A, so that it is safe to use 
on any 15A or 20A 120V outlet.  I believe that some aftermarket cords may be 
available with a 16A pilot signal or the ability for the user to configure the 
cord for either 12A or 16A, however, I an unaware of an OEM cord with this 
capability.

> One can buy a J1772 to NEMA
> adapter; however, they are not safe to use.  All these adapters "fake out"
> the EVSE and the user must be aware of the limitations.  It would not
> surprise me to see these adapters outlawed.

I'm not sure what sort of adapter you are thinking of.  As far as I know, every 
OEM that offers an EV with a J1772 charge inlet wither includes or offers a 
120V J1772 "opportunity charge" cord.  This cord *is* a proper J1772 EVSE and 
not only provides an appropriate pilot signal to the vehicle, but also does not 
energise the charging plug until it senses that it is mated with a J1772 
receptacle.

I can't see how one of these NEMA to J1772 opportunity charge cords can 
possibly be *less* safe than an ordinary NEMA extension cord between the outlet 
and a charger on the vehicle.

Cheers,

Roger.

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Re: [EVDL] Insurance Forensic Eng crying wolf ... (does this explain why Insurers' EV-uptake is slow?)

2016-10-31 Thread Roger Stockton via EV
Cor van de Water wrote:

> Battery Disposal Cost:
> "When a battery-powered electric vehicle is involved in a collision,
>  the battery needs to be removed, discharged, frozen and then destroyed.
>  Getting rid of a large, lithium-ion battery can cost upwards of
> $30,000.00"
> Say what? Frozen? As in putting it into a freezer and freezing the
> battery?
> Why would anyone want to do that to a Lithium battery? Makes no sense at
> all.

Not a freezer: liquid nitrogen.  Apparently, this is actually one way that 
*damaged* Li batteries are (or have been) recycled: freeze them with liquid 
nitrogen to render them inert, then put them into a huge shredder.

It is not one of the ways mentioned in this paper, so perhaps it is no longer 
in use, or was never in widespread use?



Cheers,

Roger.



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Re: [EVDL] 2nd life for lithium batteries

2016-10-14 Thread Roger Stockton via EV
Michael Ross wrote:

> You are correct it is a form of accelerated life testing, but very
> different from traditional testing for Li ion batteries. Almost
> unrecognisable in comparison.

Perhaps this is true of some more recent test regimen he has adopted; what he 
described in the presentation I'm referring to was the use of high precision 
measurements of the coulombic efficiency to allow prediction of the lifetime 
based on measurements made over the course of days or weeks rather than months 
or years.

Measuring the coulombic efficiency requires cycling the cell(s), as what one is 
interested in is how much of the energy delivered to the cell on each charge 
cycle is *not* recovered on the subsequent discharge.

> I don't know about the AABC meeting.  Do you know if there is a video or
> transcript available?

The presentation I am referring to was the keynote address at the Large Lithium 
Ion Battery Technology and Application (LLIBTA) Symposium as part of the 2012 
Advanced Automotive Battery Conference (AABC).  I expect that the organisers 
would be more than happy to sell you a copy of the LLIBTA 2012 proceedings:



Cheers,

Roger.

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Re: [EVDL] 2nd life for lithium batteries

2016-10-14 Thread Roger Stockton via EV
Michael Ross wrote:

> Even though marketing likes accelerated life testing, and it
> gives a higher comfort level to everyone, accelerated life
> testing can just take resources away from ​more serious
> investigation​;


> This is where the work at Dalhousie got its motivation.

[...]

> Their approach was to jump up the accuracy of testing by orders of
> magnitude.  In a nutshell they built top of the line​​ test​
> equipment using very high quality current sources, they performed testing
> in thermal chambers maintaining extremely steady, elevated temperatures,
> and so on, all to reduce environmental and measurement noise and
> uncertainty.  Through these means they were able to detect very small
> levels of cell deterioration and malfunction, ​while NOT cycling the
> cells; instead simply maintaining the damaging conditions and
> stopping occasionally to examine cell function (capacity, resistance,
> etc.), the test periods were drastically reduced from accelerated life
> testing protocols.

First of all, what you describe *is* accelerated life testing, whether the 
cells are being cycled or not.

Secondly, you are mistaken about the not cycling part; the presentation that 
Dr. Dahn gave at AABC a few years ago describing the high precision test 
equipment they had designed and how it was being used specifically stated that 
the purpose of the high precision equipment was to allow the measurement of the 
(hopefully ;^) very small amounts of capacity loss that results each time the 
cell is *cycled*.  Since the capacity loss is (supposedly) linear with the 
number of cycles, the higher precision test equipment allowed them to determine 
the rate of capacity loss while performing much fewer cycles than had 
traditionally been required, and it was then possible to extrapolate from the 
measured capacity loss per cycle to predict the cell cycle life to whatever 
residual capacity level one wanted.

He may certainly have moved to the test regime you describe in more recent 
times, however this was not the original intent behind the development of the 
high precision test equipment.

Cheers,

Roger.

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Re: [EVDL] Off-grid solar house and electric car charging

2016-06-08 Thread Roger Stockton via EV
Cor van de Water wrote:

> Roger,
> You used the wrong definition. The Wikipedia quote is about the power
> delivered to the *load* but the discussion was about the power losses in
> the *wire* feeding the load.

No; just as the power dissipated in a resistive load remains the same, the 
power dissipated in the wire feeding the load remains the same.

To see that this must be true, consider the case of a source connected to a 
non-zero load by wires with zero resistance: the dissipation in the load is the 
same for 1A DC or 1Arms.

Now, consider a zero-ohm load connected to the source by wires with non-zero 
resistance: the dissipation in the wires is the same for 1A DC or 1Arms.

The principle of superposition allows us to see that this situation holds for 
any combination of load and wire resistances: 1A DC and 1Arms will dissipate 
the same energy in the wires to the load, and they also dissipate the same 
energy in the load, though of course the amounts dissipated in the wire or load 
depends upon their respective resistance.

> To use a simple and somewhat excessive example as illustration:
> Case A: DC power to an (arbitrary) load: 1 Amp continuous, 1 Ohm line
> resistance so 1 Volt drop, meaning 1V * 1A = 1Watt of loss in the line.
> 
> Case B: power provided with 10% duty cycle so 10A during 10% of the
> period and 0 during 90% of the period. Average current still 1A and same
> power delivered to the load as in case A.
> However, the line load is still 1 Ohm so the 10A current causes a 10V
> drop and thus 100 Watt power is lost in the line during the 10% that the
> current is flowing, the average power loss in the line is therefor: 100W
> * 10% = 10W
> so the average power loss in the line is 10 times as high as in case A
> due to the peak current being 10 times as high, even though it is only
> flowing 1/10th of the time.

No.  You are confusing average with RMS; the two are not necessarily the same.

The RMS value of your 10% duty 10A peak square wave is 3.16Arms, and this will 
indeed have higher I2R loss than a 1A DC current.

For your 10A peak square wave to have an RMS value of 1A, it needs a duty cycle 
of 1%:
 RMS = peak * sqrt(duty cycle); average = peak * duty cycle.

Cheers,

Roger.
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Re: [EVDL] Off-grid solar house and electric car charging

2016-06-08 Thread Roger Stockton via EV
Robert Bruninga wrote:

> Yes, as far as VOLTS and as AMPS as averages are concerned.  Such as
> average power.  A 1500W resistor will be 1500W whether on DC or RMS AC.
> 
> But the power loss in wires feeding that resistor will have greater loss
> on AC because of two factors important in distribution systems:
> 
> 1) SKIN EFFECT where the AC current is pushed to the outside of the wire
> so that not all the wire is carrying the same current.  Thus the wire is
> not as effective since not all of its copper is being used in an AC system

The skin depth in copper at 60Hz is 8.47mm; this means that until you are using 
a conductor with a diameter greater than 2 x 8.47mm = 16.94mm (about 0.67"), 
the AC resistance is the same as the DC resistance.



> 2) Peak power losses.  As you note, the RMS current  is the same, but the
> PEAK current is 1.4 times higher during the peak of the waveform and since
> that is where the most power is delivered that is also where the most loss
> occurs in the wire.  So the average power lost in the wire for AC is
> almost twice (1.4 squared) the loss in the same wire at DC.
> 
> Google it...

"For a cyclically alternating electric current, RMS is equal to the value of 
the direct current that would produce the same power dissipation in a resistive 
load."
 - 

Cheers,

Roger.

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Re: [EVDL] Charger connector options

2016-05-20 Thread Roger Stockton via EV
Christopher Darilek wrote:

> How would you mount the car-side PowerPole connector?  Pigtail
> somewhere?  I have a hole in the side of my car I'd like to use to mount
> it..

Have a look at the PowerPole datasheet on Anderson's site:



I would use one of the plug shells for the cable-mounted charger-side connector 
and a receptacle shell to allow the vehicle-side connector to be panel-mounted.

You can see some examples of both here:



Cheers,

Roger.


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Re: [EVDL] Charger connector options

2016-05-19 Thread Roger Stockton via EV
Christopher Darilek wrote:

> I'm ready to upgrade my charger connector.  Right now I'm using NEMA plugs
> on the ends of pig tails under the hood (I have to open my hood 2x a
> day).  My charge rate is 18A @100V (reduced to not melt said plugs).  I
> think I need 5 connections:  +100V, battery ground, +12V, chassis ground,
> and BMS output to turn the charger Off.  I'd like for the connector to be
> accessible without opening the hood.  What do ya'll use?  Any ideas?

I'd suggest Anderson PowerPole connectors for this:



My first EV also used a large offboard transformer-type charger (Lester), and 
also required both pack voltage and 12V connections between the vehicle and 
charger.  It used a 4-pole PowerPole configuration for this.  In my case, the 
charger needed to see 12V from the vehicle to turn on its output.

You can choose different colours to color-code each contact according to 
purpose, and Anderson sells housings to allow the vehicle side connector to be 
mounted behind a fuel filler door, or somewhere else convenient and to allow 
the off board connector to be covered and treated as a 'paddle'.

This way there is no risk of future confusion resulting in something other than 
the intended charger being connected to the vehicle, and you have a connector 
system rated to make/break DC (which a re-purposed AC connector may not be).

Cheers,

Roger.


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Re: [EVDL] EVLN: What You Need To Know To Wire A Garage EVSE

2016-03-07 Thread Roger Stockton via EV
Peter C. Thompson wrote:

> I didn't claim that it made any sense.  :)  I agree that having the
> 14-50 plug in the garage makes a lot of sense (which is what I have -
> for welding, of course).

I think the use of NEMA 6-xx connectors makes sense given that the J1772 EVSE 
is a 240V *only* device, and so has no need for the neutral connection provided 
by the NEMA 14-xx receptacles.  If you install a NEMA 14-xx receptacle, you 
must run 4-conductors rather than the 3 required by the NEMA 6-xx receptacle.

If you already have a receptacle of suitable ampacity installed, then it makes 
sense to change the plug on the EVSE to match (cheapest option).

If you plan to haul the EVSE around with you and plug in a RV sites (I believe 
a minority of EV owners fall into this category), then using a similar 
connector at home (or making an adapter cable) is practical.

With respect to invalidating the UL marking on the product, I believe that as 
long as you do not *open* the unit the UL marking remains valid.  That is, 
changing the plug on the end of the cord is (I believe) fine, but if you open 
the case and replace the entire cordset (e.g. it is sometimes cheaper - and 
easier - to buy a range or dryer cordset with the NEMA 14-xx plug molded on 
than to buy the NEMA 14-xx plug on its own), then the UL mark becomes invalid.

This is why some products locate a terminal strip or similar connection means 
for the AC cord outside of the product under some sort of small cover.  You can 
then attach/replace the AC cord without opening the product.

As was hinted at in an earlier message, the UL marking is based not only on the 
product itself but also the production/assembly process, and so if the product 
is opened for service or repair outside of an approved service facility, then 
the UL mark becomes void.

Disclaimer: I am not a regulatory expert; this is just how it has been 
explained to me. ;^>

Cheers,

Roger.

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Re: [EVDL] The reasons for a solar car.

2016-02-05 Thread Roger Stockton via EV
Peri Hartman wrote:

> I don't think the desire for crash safety will go away.  Just because
> the odds decrease doesn't mean one doesn't want protection.  I can go
> on, but I think everyone knows what I mean.

In a word: "Titanic". ;^>

Cheers,

Roger.

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Re: [EVDL] The secrets of Avcon or smashing the hell out of a glued together claw.

2016-01-27 Thread Roger Stockton via EV
The Avcon connector is as specified in SAE J1772-2001.

The standard inlet is capable of AC Level 1 and 2 charging and is required to 
support only 4 out of 9 possible contacts:

Contact #1 (4.6mm dia): charger 1 (AC hot or Neutral in the case of Level 1 
(120VAC))
Contact #2 (4.6mm dia): charger 2 (AC hot)
Contact #5 (8.0mm dia): chassis ground
Contact #6 (3.1mm dia): control pilot

As (Cor, I believe) already stated, the Avcon connector system implements 
proximity via a reed switch and magnet; the reed switch is in the vehicle-side 
inlet while the magnet is in the EVSE paddle.

I suspect that the second small (green?) wire is connected to contact #9 (3.1mm 
dia), which is the ground connection for the optional communication lines 
(contacts #7 & 8).

Contacts #1 and 2 are in the middle of the row; contact #6 is immediately 
adjacent to contact #1; contact #9 is at the outside end of the row (unused 
contact #8 separates contact #9 from contact #2):

-4  9 - communication ground (optional)
-4  8 -
2 - AC hot
chassis gnd -5
1 - AC hot or neutral
-3  6 - control pilot 
-3  7 -

Hope this helps,

Roger. 

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Re: [EVDL] EVLN: This Is The GM-200mi EV Before You Are Supposed To See It (v)

2016-01-07 Thread Roger Stockton via EV
Michael Ross wrote:

> It is a bit of a bugaboo that weight is important in terms of energy
> consumption. More important is air drag losses, and rolling resistance.
> In the thought experiment where there are no losses to friction, the
> weight is meaningless except for whatever change in elevation there is
> from start to finish - if you go down overall you actually benefit from
> greater gravitational potential at least for that trip. But, it is
> really a wash in the theoretical sense..
> 
> Yes, it takes more energy to get the heavier vehicle up to speed, but that
> is then inertia, and you get it back with some regen instead of wasteful
> brakes, or you get it back not losing as much speed when going downhill.
> The weight can add to rolling resistance (losses to heat in the tires),
> but this is really second order stuff.  If the heavier car is smoother
> in the air that is very important.

I think you may be being confused by the fact that rolling resistance is 
(relatively) independent of speed while aerodynamic losses increases 
dramatically with speed.

At higher speeds, aero losses will dominate and so can make it appear as though 
rolling resistance is unimportant, particularly if the vehicle is not all that 
aerodynamic.  As vehicles become more aerodynamic, the rolling resistance 
becomes a more significant portion of the total losses.

Rolling resistance force is *directly proportional* to the force exerted by the 
weight of the vehicle normal to the road surface; this is not a second-order 
effect.

Similarly, while *some* of the potential energy gained due to an increase in 
elevation or kinetic energy gained during acceleration can be recovered through 
regen on the descent or deceleration, not all of it can be.  The inefficiency 
of the drivetrain works against recovery of energy just as effectively as it 
works against the delivery of mechanical energy in the first place.

Cheers,

Roger.

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Re: [EVDL] temp sensors on brushes

2015-09-08 Thread Roger Stockton via EV
Mark Grasser wrote:

> I seem to remember one of the hottest points being the brushes themselves.
> I am going to drill and tap about ¼" deep for 4-40 screw on the wire end
> of the brush.  Concerns would be these: are the brushes a god point to
> read temperature? Am I in danger of splitting the brush during this
> process?
> Will the screw threads hold up? Would I be smarter attempting to epoxy
> the thermistor to the brush instead? Oh, What temperatures should I
> expect?

Convention appears to be to epoxy a thermocouple into the brush for monitoring 
brush temperatures.  The positive brushes tend to run hotter, so if you only 
monitor one, make it a positive one.

Jim Husted noted that there are downsides to attaching a temperature sensor to 
the brush, including the possibility of the sensor wiring becoming connected to 
the traction power, the sensor wiring interfering with free movement of the 
brush (e.g. most thermocouple wire is relatively stiff solid core), and that 
you have to redo the sensor when you replace the brushes.  He suggested the 
mounting the sensor to the brush holder might be a reasonable compromise.

Below are a couple of relevant posts from those more knowledgeable than I on 
this subject.

Cheers,

Roger.

> -Original Message-
> From: Otmar [mailto:otli...@evcl.com]
> Sent: July-24-05 5:54 PM
> To: e...@listproc.sjsu.edu
> Subject: Re: Thermocouple position, was: Re: 120v 6.7" ADC?
> 
> At 9:17 PM +1000 7/14/05, James Massey wrote:
> >Hi Otmar and all
> >
> >At 10:37 AM 12/07/05 -0700, Otmar wrote:
> >>I was taught by the engineers at ADC to drill a half inch deep hole
> >>in the positive brush and put the thermocouple in there.
> >
> >Any ideas as to why the positive brush?
> >
> >Is it just an ADC in-house convention, or is there a technical reason for
> it?
> >
> >I can theorise no reason for the positive brush to get hotter than
> >the negative, unless the electron flow into the brush heats it more
> >than the electron flow out of the negative one.
> >
> >Any theories?
> 
> Sorry for the delay, I've been out of town and am just getting to
> hundreds of EV list messages.
> 
> 
> I was told the positive brush gets hotter. I can only theorize that
> it has to do with electron flow.
> 
> --
> -Otmar-

> -Original Message-
> From: owner...@listproc.sjsu.edu [mailto:owner...@listproc.sjsu.edu] On
> Behalf Of Jeff Major
> Sent: June-19-07 10:42 AM
> To: e...@listproc.sjsu.edu
> Subject: Re: Max motor temperatures and temp sender install
> 
> 
> Hi Mark, Richard,
> 
> Class H insulation is 180 degree C.  Meaning at 180C,
> insulation will last 10,000 hours(or half life of
> 10,000).  It depends where the thermal sensor is
> located in the motor.  Cannot be in the armature, that
> is hard to do because it rotates.  So, I'm guessing,
> it is in the field coil.  Now it depends on the motor
> design, but the ones I worked with years ago, would,
> on the one hour temp rise test, have the armature
> reach rated temp first.  So there would be a
> differential between the arm and field coil temps.
> The temp sensor would be selected to that field coil
> temp which related to arm temp limit.  So the
> assumption would be that when your temp sensor trips,
> the hottest part of the motor is at limit.
> 
> Having a 120C temp would indicate that you should back
> off or end the trip soon, probably not stop at the
> side of the road and wait for the motor to cool down.
> You might also add forced air cooling if you find the
> temp light coming on often.
> 
> As for motor temperature in general, at the end of
> thermal rating tests I used to run, it was not
> uncommon to have the outside of the motor frame at
> 100C.  As for the brushes, we used to install
> thermocouples in the brush by carefully drilling a
> hole in the top of the brush, insulating the TC with
> epoxy and then insterting the TC into the epoxy filled
> hole.  On short time based thermal runs, like 5 or 10
> minutes or shorter, the brush would be the limiting
> temperature for the motor.  This was allowed to reach
> 200 degree C as the internal brush temperature where
> no insulation is present.  The outside of the brush
> would be lower where the pigtails and springs are.
> 
> So, for a field coil temp limit, 120 to 140C sounds
> good to me.  On the brush, I'd say 180C, hopefully
> that would be just peaks on the brush, like at the top
> of a hill, and the average would be 40 or 50 lower.
> 
> My experience was back in the good old days, so I
> don't really know how they design those new motors.
> Hope that helps.
> 
> Jeff


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Re: [EVDL] 48V Energy Meter (Lead-Acid)...

2015-07-25 Thread Roger Stockton via EV
damon henry wrote:

 I have been around and using E-meters for many years now and this is the
 first time I have ever heard of using a zener diode as a method to create
 an isolated power supply for one.  Is it really that simple?

Yes, but it does not provide an ~isolated~ supply.

[...]

 If I understand this method I would simply connect the emeter power
 through a zener diode off my traction pack and that would provide both the
 required isolation and enough of a voltage drop to keep from burning the
 meter out.  That sounds easy :) Do you just wire the zener into one of the
 power leads from the traction pack to the emeter?  Does it matter whether
 it is on the positive or negative lead?  Are there other components that
 could/should be added like a fuse or current limiting resistor?

Correct.  Place the zener in series with the positive power wire from the pack, 
oriented such that it drops the pack voltage by the zener voltage (if you wire 
it backwards, it will drop only an ordinary forward diode drop of 0.7V and you 
will probably fry the meter).

You cannot place the zener in series with the negative supply wire since the 
E-meter supply ground is common with the traction pack voltage sense ground.

Normally, we need to provide a small isolated DC/DC to power the E-meter, but 
this isolation requirement is because the E-Meter connects the traction pack 
negative (from its voltage sense) to the supply ground and we don't want our 
12V house battery/supply to be referenced to the traction pack.

For a 48V pack, you may be less concerned with ensuring the traction pack is 
isolated from the chassis, and if only the E-meter is powered from the pack via 
the zener, then it remains isolated from the 12V system anyway.

What are you using on your bike to power the lights, horn, etc.?  If you have a 
12V battery or DC/DC for this anyway, then you could just power the E-meter 
from this 12V source.  Doing so will result in the E-meter connecting traction 
pack negative to the 12V ground (chassis), defeating any isolation your present 
DC/DC offers, however, at traction pack voltages of 48V or less it is not 
uncommon for non-isolated DC/DCs or voltage taps off the traction pack to be 
used to power 12V accessories.

Include the same fusing in the power lines to the E-meter as you normally do 
(or as shown in the manual if you've been neglecting fusing ;^)

Cheers,

Roger.

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Re: [EVDL] EVLN: Zombie222 electric 1968 Mustang 0-60mph:2s destroys Tesla-SP85D

2015-06-25 Thread Roger Stockton via EV
Ben Goren wrote:

 Erm...I don't think you understand how these things work. I very, very
 much doubt it's like Weyland sought out the Tesla to race; rather, almost
 certainly, both of them showed up to the same event, ran in a number of
 races against all sorts of vehicles, and the Zombie and the Tesla just
 happened to get paired up for this particular race.

Erm... I don't believe you've met John Wayland (not Weyland) ;^

It is possible that it was a random matchup, but it is (in my opinion) at 
*least* as likely that the race was specifically arranged.  While John is part 
of the team that built the car, I don't know if he was present at this 
particular race.  However, he has been known to arrange races between his White 
Zombie and select vehicles that happen to be at the track in the past.  John is 
*very* persuasive and charismatic, and has a distinct skill at setting up 
crowd-pleasing matches that his vehicle tends to win.

Cheers,

Roger.


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Re: [EVDL] EVLN: Zombie222 electric 1968 Mustang 0-60mph:2s destroys Tesla-SP85D

2015-06-25 Thread Roger Stockton via EV
Ben Goren wrote:

  This whole exercise seems rather childish.
 
 If that's the case, then _all_ amateur racing for all time is and has been
 childish...and amateur sports, and all hobbies, and so on. Why would you
 waste time with paint and canvas when a camera is so much faster, easier,
 and accurate?
 
 And isn't that the point, after all? To have some fun? I mean, these guys
 have built the fastest '60s-era Mustang _ever,_ and it's an electric
 vehicle. In what alternate universe is that _not_ effin' awesome? And why
 would you ever want to visit that universe, let alone live there?

David's point, I believe is that the exercise of pitting a highly modified, 
purpose-built drag racer against a production car is rather childish, not 
necessarily that building and racing the Mustang is.

As you admit, the outcome of such a matchup was hardly ever in doubt; this is 
what makes it childish.  Likewise, it would be hardly surprising if the Tesla 
and Zombie222 were but on a road course and the Tesla bested the Zombie222; 
after all, the Zombie has been optimised to accelerate as quickly as possible 
in a straight line on a flat surface for 1320ft: period.

Put the Zombie222 up against similarly purpose-built ICE or EV drag racers; the 
outcome of *that* matchup would be entirely relevant and unchildish.

Cheers,

Roger.

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Re: [EVDL] Zero self-discharge

2015-06-23 Thread Roger Stockton via EV
Michael Ross wrote:

 It is like a bunch of people simply don't want to understand that things
 are not uniform across the field, that there is old tech that is being
 surpassed, and that some things are turning out very well.
 
 I would restate,  I think it is possible that people don't recognise that
 some old and inferior cell designs do not represent what is possible,
 demonstrable and manufacturable.

It seems you are ready to conveniently ignore the literature that you are happy 
to quote to others.

There may or may not be something new about LiFePO4 chemistry that renders it 
immune to self-discharge, however, if there is, it is *not* the simple fact 
that lithium intercalation is involved, and this is something that you have 
been stating/purporting.

Again, I refer you to your copy of Linden's Handbook of Batteries, which 
clearly states and quantifies self-discharge amounts for various lithium 
chemistries that *all* also rely upon lithium intercalation.

If your claim is that something about LiFePO4 (in general, in theory, or some 
specific example?) that makes it immune to self-discharge, please make this 
clear in your posts, and accept that whatever this property is, it is not 
simply that LiFePO4 (like those other 'old and inferior [lithium] cell 
designs') relies upon lithium intercalation.

Cheers,

Roger.

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Re: [EVDL] article: World's first 1 megawatt all-electric race car to compete at Pikes Peak

2015-04-03 Thread Roger Stockton via EV
Rush Dougherty wrote:

 Roger - Great photos of Woodburn, any more somewhere?

Thanks.  There are more from Woodburn '99 accessible from the index page:

http://www.veva.bc.ca/woodburn/1999/index.htm

And a few from 2000 at:

http://www.veva.bc.ca/woodburn/2000/index.htm

(I didn't get many photos in 2000 as I was assisting Rod Wilde prep the Maniac 
Mazda most of the day.)

I'm sure I have more on hand from these (and possibly other) years, however, 
these really are photos, and those linked above are probably the only ones 
I've scanned.

Cheers,

Roger.

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Re: [EVDL] article: World’s first 1 megawatt all-electric race car to compete at Pikes Peak

2015-04-02 Thread Roger Stockton via EV
Ben Goren wrote:

 Sorry -- I was referring to them seem to really be building a real race
 car, not attempting to verify their claims to bragging rights. The
 megawatt bit, honestly, didn't even register
 
 b
 
 On Apr 2, 2015, at 6:15 PM, Ben Apollonio via EV ev@lists.evdl.org
 wrote:
 
  Really?  I was pretty sure the title of first megawatt all-electric
 race car went to the Maniac Mazda over a decade ago...
 
  -Ben

I'm not sure if Maniac Mazda satisfied the 'megawatt' bit, however, Bob Boyd's 
'Megawatt Monster' dragster should have satisfied both the 'megawatt' and 
'all-electric race car' bits, and this (as well as Maniac Mazda) were well over 
a decade ago.

I didn't find specs on the Megawatt monster in a quick search (the car's tranny 
failed at what I believe to be its first real outing, and Bob's health failed 
shortly afterward such that the car's drivetrain was parted out; the Silver 
Bullet (IIRC) ended up with one of its two triplets of motors).

It seems these pictures I took at the Woodburn drags in '99 are still online 
though.  You can clearly see the 6 motors, 3 1200-amp DC controllers, and part 
of the pack of Johnson Controls Inspira AGMs:

http://www.veva.bc.ca/woodburn/1999/8415020a.htm

http://www.veva.bc.ca/woodburn/1999/8415021a.htm

http://www.veva.bc.ca/woodburn/1999/8415023a.htm

It appears that the present incarnation of Maniac Mazda at the same time 
sported 4 1200-amp DCP controllers, so perhaps it was indeed capable of 
'megawatt' level operation:

http://www.veva.bc.ca/woodburn/1999/7080033.htm

http://www.veva.bc.ca/woodburn/1999/783000e.htm

Cheers,

Roger.

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Re: [EVDL] Q about using an electronic load.

2014-11-07 Thread Roger Stockton via EV
Michael Ross wrote:

 I think I need to be a notch or two above garage testing.  To provide
 results worth referencing.  I do have to be frugal and not spend where
 good things can be fabricated.  We want to be cost effective for clients
 that aren't at the million$ a year in sales level.

Thanks for clarifying that this is NOT a personal project, but a commercial one.

I think you will find that if you are doing testing for hire, that there is 
significant value in the credibility that comes with using professional grade 
commercial equipment versus explaining to the client that the coat hanger in 
that garbage can full of water really is a sensible piece of equipment for the 
test they are paying you to execute ;^

The cost effectiveness for smaller clients comes from *you* bearing the 
multi-$1000 investment in a proper active load and data acquisition and control 
equipment and possibly power supplies (for charging), and then recovering the 
cost over multiple clients and over time so that they have access to this level 
of test capability, when needed, for a much smaller up-front or per-instance 
expenditure.

If you are able to consider sufficiently large electronic loads, then ones that 
can push the energy back into the grid rather than dissipating it as heat 
become an option.  This capability doesn’t really become available until you 
are looking at loads of at least 6kW, and you should check with your local 
utility to see what sort of barriers will face you in trying to connect such a 
load before buying.

 I have a pretty comprehensive data acquisition system, National
 Instruments cRIO controller, 32, 5V biderectional DIO channels, 8 channels
 of high speed 5V bidirectional DIO, 16 channels of 24V DO, 8 channels of
 analog  input.  I have a couple 6 1/2 digit DMMs and 3  20 channel cards
 to use in them (slow but accurate).  All that can be programmed with some
 sophistication using LabVIEW.

Great!  For battery testing you generally don't need particularly fast scan 
speeds.  I'm not sure just what your 6.5-digit DMMs are, but they sound similar 
to the Agilent units I use for battery testing.  It is particularly nice that 
they can directly measure pack and cell voltages as well as shunts and 
thermocouples for monitoring temperature.  As long as the number of channels 
you are scanning isn't too great, it is possible to get at least a few readings 
per second in the uncommon event that your test requires it.  More typically, 
recording data at 1-10 second intervals is plenty fast for battery cycle 
testing.

 I won't need PLCs.

Also great, though I referred to use of a *PC*, same as you will use to run 
your LabVIEW application to control things ;^

 For cell testing I have an EMS 7.5V 300A 1700W supply.  I have not really
 used it, so I don't know exactly how to control it automatically.  It
 could do cell modules, but not packs.
 
 Then I have a couple of transformers in Lestronic II PbSO4 chargers 24V
 25Amp, and 36V 30A.  And I have a 480V:120V 7.5KVA transformer that ought
 to be useful somehow.

The power supply sounds like it could be useful, especially if equipped with 
IEEE-488 and if a LabVIEW driver is available for it.  The transformers sound 
less promising, at least for this purpose.

Really, it comes down to the sort of clientele you will serve and what sort of 
testing they require.  They may want you to test specific cells/modules, either 
recharging them using a provided charger or using your programmable supply to 
implement some specified charge regimen.
 
You may need to consider investing in water baths to maintain consistent 
temperatures throughout the test pack, and/or an environmental chamber to allow 
testing at elevated or reduced temperatures.  If you are going to test Li 
chemistries, especially at high rates and/or elevated temperatures, investigate 
the safety requirements for appropriate fire suppression and ventilation, etc.  
If you will be testing flooded lead acid, investigate the spill containment and 
personal safety requirements (eye wash, emergency shower, etc.), as well as 
hydrogen sensing equipment and ventilation requirements.

A properly equipped (inert gas purge, explosion proof locking door, suitable 
pressure relief fearture, possibly reinforced to handle the weight of larger 
(especially lead-acid) packs, etc.) environmental chamber runs about $60K, so 
once again part of the value provided for smaller clients is the ability for 
them to avoid the need to make this sort of investment in test equipment.

 I think I also want some reference standards.  But, I
 might make them, or settle for the calibrated DMMs.

The route you choose may depend on what you already do for other equipment in 
your lab, however, the approach we've taken is to maintain the calibration on 
the DMM/data acquisition units and rely on them to control the loads and power 
supplies so that the loads and power supplies themselves don't need to be kept 
calibrated.


Re: [EVDL] Q about using an electronic load.

2014-11-07 Thread Roger Stockton via EV
John Lussmyer wrote:

 If you are able to consider sufficiently large electronic loads, then
 ones that can push the energy back into the grid rather than dissipating
 it as heat become an option.  This capability doesn?t really become
 available until you are looking at loads of at least 6kW, and you should
 check with your local utility to see what sort of barriers will face you
 in trying to connect such a load before buying.
 
 Well, there are grid-tie inverters down as small as 200W or so readily
 available, often down to 12v input.

And these can certainly be a viable option, IF the batteries you are testing 
are compatible with the (typically) narrow input range of such inverters.  If 
you need to be able to test battery packs of arbitrary voltage and perhaps 
discharge to unusual (at least for typical lead-acid packs) end-of-discharge 
voltages, then off-the-shelf inverters may not be viable.

Cheers,

Roger.
 
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Re: [EVDL] Q about using an electronic load.

2014-11-06 Thread Roger Stockton via EV
Michael Ross wrote:

 If I have a programmable electronic load, rather than purely resistive
 loads, is this an unrealistic way to discharge batteries?
 
 I gather they use power MOSFETS and switch them to product the desired
 output current from the batteries.  I think this implies some transients
 at some frequency.

A programmable load is fine for discharging batteries.

I believe the power devices are operated in linear mode, not PWMed, and have 
not observed any transients on the load current on any of the electronic loads 
I've used.

Cheers,

Roger.

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Re: [EVDL] Q about using an electronic load.

2014-11-06 Thread Roger Stockton via EV
Michael Ross wrote:

 I have heard of putting a roll of fencing in a tank to steam off heat.  Is
 this useful with a programmable load?  Or is this just a crude way to
 discharge.

Probably not, unless the electronic load you choose is designed to be used with 
an external load bank, or you plan to control the electronic load from a remote 
source rather than simply setting it to regulate the desired load current on 
its own.

An external load bank (coat hanger or other wire in a bucket of water or 
fan-cooled power resistors, etc.) can be useful if you want to increase the 
power capability of your electronic load (or conversely, to be able to use a 
smaller - and cheaper - electronic load than you could otherwise).

For instance, when testing a 12V battery you will typically discharge to about 
10V minimum; if your desired discharge rate is 75A, then your minimum load is 
about 750W.  If you want to be sure that you can pull the full 75A from a 
freshly charged battery, it needs to be able to handle the maximum load of 
about 15V x 75A = 1125W.  If you use a resistive load to handle most of the 
minimum load requirement, then your electronic load only needs to be sized to 
handle the difference (in this case 1125-750 = 375W) instead of the full amount.

 Someone mentioned needing a heat dispensing means would be needed with a
 programmable load.

Not unless you pick up a water-cooled load.  The air-cooled loads have built in 
fans and will cool themselves.  If you are discharging a large capacity battery 
in a small room, you may need to open a window or otherwise allow for some 
ventilation as the room will warm up.

 Any recommendation of actual units to look at?

I've mostly used DLP- and RBL-series units from TDI (Transistor Devices).  They 
are often available used, and are generally basic rugged units.  You don't need 
particularly fancy features for battery discharging as most often you will use 
the load in constant current or possibly constant power.  In constant current 
mode, the TDI loads can have the load current controlled remotely by a 0-5V 
signal, so you can use an external means to monitor the total load current 
drawn by the electronic load and a resistive load and then control the 
electronic load to regulate the total current at the desired level.  They also 
can be enabled/disabled remotely with a simple relay or opto so that your data 
logger can turn the load off when the battery voltage reaches the desired 
end-of-discharge voltage.  Some models support IEEE-488 (GPIB) communication, 
in which case you can achieve all of this controllability through software 
control, provided you spring for a GPIB interface for your PC.

I've also used loads from NH Research (NHR, this is what I have at home) and 
Chroma.

This site provides an idea of what sort of devices are available on the used 
market:

http://www.alltest.net/s.nl/sc.2/category.16/.f

Cheers,

Roger.

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Re: [EVDL] Q about using an electronic load.

2014-11-06 Thread Roger Stockton via EV
Michael Ross wrote:

 I am investigating how to test cells and packs - I will need to charge and
 discharge.
 
 If I have a programmable electronic load, rather than purely resistive
 loads, is this an unrealistic way to discharge batteries?

Thought I'd mention that while a programmable load is an *excellent* way to 
discharge when testing batteries, it can be pricey (typically about $2/W on the 
used market).  If you have a load bank, or need one for other reasons, then by 
all means use it.  If you are considering buying one just for this purpose, 
then carefully consider what other equipment you have or will need to acquire 
to go with it.

If you get a load large enough to handle your needs on its own (i.e. it can 
handle the desired discharge current even with a fully-charge battery), and you 
get one equipped with a communications interface (GPIB/IEEE-488 or RS232, 
typically), then you may be able to use its own voltage and current measurement 
capabilities to avoid the need to purchase a standalone data logger or USB 
DAC/digital I/O device to take measurements and control things.

If you already have a data logger or other means of measuring/controlling a 
load and charger, then perhaps consider using a passive load in parallel with a 
smaller electronic load, so that you can save money on the electronic load 
purchase.

Or, you may be able to go in entirely the opposite direction and use a 
completely passive load bank.  I started out with a battery cycler setup 
consisting of a bank of 12VDC Edison-base (household screw-type) light bulbs 
switched by a continuous duty Ford starter solenoid-type RV battery switch.  A 
simple QBasic program on an old laptop controlled the relay for the load and 
another for the charger via the parallel port.  An E-meter with the RS232 comms 
option provided voltage, current, etc. measurements to the QBasic program.

Incandescent bulbs have the nice property that the current they draw varies 
less with voltage than would a purely resistive load, so you can get a 
reasonably constant discharge current simply.  Unless your battery voltage is 
significantly below the rated voltage of the bulbs, they also provide a nice 
visual indication that they are on and hot. ;^

Cheers,

Roger.

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Re: [EVDL] EValert: !Don't buy a salvaged Tesla EV to repair drive! (video)

2014-10-02 Thread Roger Stockton via EV
Mike Nickerson wrote:

 It is a good thing when a vehicle like a Tesla disables itself in an
 accident.  Even my conversion does that.  I have an inertial switch to
 disconnect the traction pack in the event of an accident.
 
 Now, in my case, I just need to reset that sensor.  I'm sure Tesla has
 something much more exotic.  However, I don't think you can argue against
 disabling the output of an 85 kWh pack during an accident!

Let's consider this statement for a minute.

The energy content of gasoline is 32.4MJ/L, and 1MJ=0.28kWh; so, a 10 (US) 
gallon tank of ordinary gasoline contains 343kWh of energy, and yet every other 
auto manufacturer has *millions* of vehicles on the road with a 
manually-resettable-by-anyone inertia switch to disable this energy source in 
the event of a sufficiently serious accident.

Yes, a means of automatically disabling/disconnecting the traction pack in the 
event of an accident makes sense for ~any~ EV, however, there is no obvious 
justification for this feature not being manually resettable without the 
assistance of the manufacturer.  It seems reasonable that the vehicle might 
have the intelligence to refuse to re-enable should its onboard diagnostics 
determine that something is unsafe or defective with its systems (in the same 
way that a manually-resettable circuit breaker will immediately re-open if the 
a fault condition persists), but again it is not obvious that there is any need 
for the involvement of the manufacturer.

Cheers,

Roger.

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Re: [EVDL] Flooded lead-acid ooopsie and how to correct best?

2014-08-11 Thread Roger Stockton via EV
Cor van de Water wrote:

 I presume that you meant to say unless it's very high in minerals
 and luckily our water is the softest in the area. I grabbed the water
 report from the city and saw that our tap water has on average only
 71 PPM (Parts per Million) total dissolved solids, of which
 53 PPM calcium carbonate
 12 PPM sodium
 
 The average Ph is 8.4 but varies between 6.5 and 9.4 since the total
 dissolved solids can vary between almost 0 and 109 PPM.
 That does mean that there are some impurities added to the cells, but
 not a large amount and since the amount of tapwater was approx 5% of the
 total fluid contents of the cell (my estimate) the total impurity level
 is about 3-4 PPM added total dissolved solids.
 I am no battery engineer though, so I do not know how bad that is,
 please enlighten me. Or time will tell...

Here is a Trojan whitepaper describing max allowable PPM for various impurities 
and the detrimental effects of each:

http://www.trojanbattery.com/pdf/WP_EffectOfImpurities_0612.pdf

For your over-filled cell(s), I would just remove electrolyte from the cell 
until the level is restored to normal.  If you don't, you are likely to lose 
electrolyte during charge and use of the vehicle due to leakage out of the cell 
caps.  Reserve this electrolyte and use it to top the cell up to normal level 
at your regular watering interval until it has all been added back to the cell.

If you haven't yet driven or charged, then the liquid at the top of the cell is 
likely almost all just the water that you added, with relatively little 
electrolyte mixed in (the lower SG water will 'float' on top of the heavier SG 
electrolyte that was in the cell to start with).

Cheers,

Roger.
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Re: [EVDL] Flooded lead-acid ooopsie and how to correct best?

2014-08-11 Thread Roger Stockton via EV
Cor van de Water wrote:

 I have added a little dam of baking soda around the fill hole of that
 cell, so if it spills during the end of charging, it should get
 neuralized.

As I expect you realise, my concern regarding loss of electrolyte due to 
spillage is that when this happens, you are losing both acid and water instead 
of (mostly) just water as in normal gassing.  Losing both acid and water means 
that your acid strength will drop when you top up the cell, even if you use the 
reserved electrolyte.

 I am not sure why one battery remains sealed and clean, while another
 one constantly weeps elecrolyte. Probably a mechanical issue that the
 seal of some fill holes is not seated properly. I am using the ganged
 caps that allow all 3 holes to be opened/closed together.

Most likely a mechanical issue with the ganged caps.  Given that you water 
infrequently, you might want to check with your dealer to see if they will 
supply you with individual caps.  The individual caps tend to seal the best, 
and I believe are available upon request for little or no charge (unless your 
dealer just can't be bothered to get them for you).

Cheers,

Roger.

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Re: [EVDL] Hybrid Mustang: motorcycle drivetrain?

2014-08-06 Thread Roger Stockton via EV
Dennis Miles wrote:

 {Ben, autos stopped using chain or belt
 drives 80 years ago, I like using the 4WD transfer case with the 2::1 low
 range for in town and 1::1 on highway coupled with the stock 3.0::1 in the
 rear axle differential.

I realise it isn't quite what you meant, and I don't profess to profess to be 
an expert on modern transfer cases, but those I am familiar with (which are 
less than 80yrs old ;^), have contained a chain drive running in an oil bath.  
While a transfer case would be an elegant way to reduce the custom fabrication 
required, it won't necessarily avoid the use of a chain drive.

Cheers,

Roger.
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Re: [EVDL] Hybrid Mustang: motorcycle drivetrain?

2014-08-06 Thread Roger Stockton via EV
Ben Goren wrote:

 Very interesting! That exact design won't work, as I'm keeping the V8 --
 but the basic geometry is very similar to what I have in mind.

Understood; I was thinking that it might be easier to modify the combiner 
output shaft to be double-ended so that one side attaches to the tranny output 
and the (shortened) driveshaft attaches to the other, possibly with the torque 
combiner bolting right up to the tranny much like some transfer cases do.

 Thanks for that. I'm not sure I'm understanding the math right, but I
 *think* Harley belt drives are supposed to be tensioned to 10 lbf. I think
 I'm reasonably sure that I've got the order of magnitude right, at least.
 Using 10 lbf radial, 100 lbf axial (the motor's torque rating), and 5000
 RPM, I get a rating of close to 2 million hours. Just for giggles, if I
 make it 100 lbf for both, it still has about a million hours rating.
 
 Any chance you can tell me if I've at least got the right order of
 magnitude? If so, I'm not going to worry. Even if it only has a 10,000
 hour lifespan, that's still over half a million miles at freeway speeds.

Sorry; I'm an EE, not ME ;^  I suspect that it is not just the static load of 
the belt tension, but the tension added to one side of the belt/chain when the 
motor is delivering torque.  I would not use the peak torque load, but the 
typical cruising condition; perhaps estimate RPM and HP required at 40mph and 
then figure out how much tension is added to the tension side of the belt under 
that torque load.

Cheers,

Roger.

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Re: [EVDL] Hybrid Mustang: motorcycle drivetrain?

2014-08-06 Thread Roger Stockton via EV
Ben Goren wrote:

  I suspect that it is not just the static load of the belt tension, but
  the tension added to one side of the belt/chain when the motor is
  delivering torque.
 
 That was my initial thought, too...until late yesterday evening when I was
 doing a bunch of research on it. And, if I'm understanding it correctly,
 all that putting a load on the system does is move the direction of the
 force, but not its magnitude -- and for a reason that makes sense: when
 you pull on the one side, you increase tension on that side...but you also
 _decrease_ tension on the opposite side by the same amount. So, instead of
 the (say) ten pounds being applied towards the axle of the opposite
 pulley, the same ten pounds is now applied on a different angle.

I believe you are mistaken.  I think what you need to consider is termed 
overhung load; this Gates document gives a good overview:

http://www.gates.com/~/media/Files/Gates/Industrial/Power%20Transmission/White%20Papers/Overhung%20Load.pdf

Near the bottom of this document it mentions belt tension and notes that the 
static tension is really just to counter the centrifugal forces that come into 
play as the belt rotates rapidly and tend to throw it outwards and neutralise 
some of the installation tension that is intended to ensure the belt teeth 
remain in intimate contact with the sprocket.

Page 168 of this document describes the calculation of overhung load, which is 
based on the HP being transmitted, the RPM, and the diameter of the sprocket:

http://www.gates.com/~/media/Files/Gates/Industrial/Power%20Transmission/Manuals/PowerGripDriveDesignManual_17195_2014.pdf

Unfortunately, there are a couple of factors in the calculation that are 
assumed to be provided by the manufacturer of the speed reducer you are using, 
so unless you can get these factors from HPEVs or the manufacturer of the 
AC-51, you'll need to do a bit of research to determine sensible ballpark 
values to use for your situation.

Cheers,

Roger.


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Re: [EVDL] Hybrid Mustang: motorcycle drivetrain?

2014-08-05 Thread Roger Stockton via EV
Lawrence Harris wrote:

 Keep in mind that if you have just gone up a long hill the motor and
 commutator will be hot and over-speeding it on the downhill run may still
 damage it even though the current is now low (or zero).  I think it's
 probably best to keep the RPM in the safe range under the worst conditions
 rather than risk the expense of a damaged motor.

Dennis Miles wrote:

 
  David, and others, the most fragile part, of a series DC motor, is the
  commutator.
 
And, bear in mind that the original poster is considering the AC-51 motor, 
which is AC, not brushed DC, and so has no commutator to worry about.

If I were the OP, I'd still want HPEVS to provide some max safe RPM value, not 
just a verbal statement that the 8000RPM limit is a controller limitation and 
not a limitation of the motor.

Roger.

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Re: [EVDL] Hybrid Mustang: motorcycle drivetrain?

2014-08-05 Thread Roger Stockton via EV
Ben Goren wrote:

 The AC-51s use 6207-2RS bearings; my main job is to research their side
 loading capacity. However, Bill says there're a number of side-loaded AC-
 35s out there, and that he thinks I'm probably okay -- though, of course,
 I need to confirm that. If anybody can suggest a good way to put some
 numbers to that, I'd appreciate it.

Not sure if it helps, but here is a specific example of a pair of HPEVs AC-31s 
installed in a side-loaded arrangement:

http://evalbum.com/4283

You can see more details of the torque combiner unit on John's (the owner's) 
site:

http://www.signaturerenewables.com/component.php

His torque combiner uses a 2:1 ratio belt drive to connect the two motors to a 
common output, and you might just be able to re-use his design in your 
application with little modification.  Certainly, it can't hurt to ask.

Regarding putting numbers on the acceptable side load, or conversely, on the 
life of the bearing under a given load condition, this Timken calculator might 
be useful:

http://www.timken.com/EN-US/Knowledge/engineers/Pages/BearingLife.aspx

Your 6207 crosses dimensionally to Timken's 207W, MM207K, and MMC207K ball 
bearings; of these, the 207W seems to have higher rated life.  On this page, 
click 'Select Type' and select BB from the list, then enter 207W into the 
part number box and click 'Lookup'.  After this you can enter radial and axial 
loads and speed values and hit 'Calculate' to see the effect on fatigue life.

My understanding is that radial (side) load is exactly what the ball bearing is 
designed to handle, and that the real concern is the axial loading that these 
bearings might be subjected to in a more typical EV conversion with a manual 
clutch.  For greater axial load capability one might want to upgrade the 
bearings to an angular contact type, however, in your case axial load should be 
minimal.

Cheers,

Roger.

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Re: [EVDL] Question about amp-hr

2014-07-10 Thread Roger Stockton via EV
Cor van de Water wrote:

 Reason is that Li-Ion batteries are sized by Ah
 so it is normal to say what size (Ah) battery cells you have,
 if you want to indicate which version cells are in your pack,
 but if you want to tell the energy in the pack then it only
 makes sense if you tell (or know) the average pack voltage to
 arrive at the kWh rating from Ah * Volts, or simply talk about kWh.

In fairness, *all* batteries are sized by Ah, so I think this reason applies 
equally regardless of the battery chemistry.

I think the reason for talking/writing in terms of Ah rather than Wh depends 
somewhat upon the context.  When buying a battery for an EV, we seldom buy a 
single battery of the entire pack voltage; instead we buy some number of 
discrete modules from which we assemble a battery that suits our specific (and 
often arbitrary) overall voltage and capacity need.  These modules may be 
individual cells (typically the case for lithium), or they may be monoblocs 
consisting of multiple cells (usually 3, 4, or 6 for PbA) in a single case.  
Either way, the individual modules are rated in terms of Ah capacity (at a 
specific discharge rate for PbA), so it is not uncommon to talk in terms of Ah 
when discussing options as the nominal voltage of the module being considered 
is often implied by the chemistry or application.

The other scenario that comes to mind is when people discuss how much energy 
their EV consumes in use, and in this case I suspect the reason Ah would be 
used instead of Wh or kWh is due to the limitations of the instrumentation 
available.  The only meaningful value is the energy consumption in [k]Wh, 
whether from the battery or outlet, however, if one has only has a gauge 
capable of reporting energy usage in Ah (or only uses the Ah display of a more 
capable meter because their primary interest is in 'fuel gauging' rather than 
energy usage), then this is the value they will offer to quantify their energy 
usage.

Cheers,

Roger.

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Re: [EVDL] EVLN: Hertz not deriding Spark EV as nothing more than a compliance car

2014-06-12 Thread Roger Stockton via EV
Rick Beebe wrote:

 There's compliance and then there's compliance. There are, I believe, 7
  states other than California that have ZEV mandates as well. I was able
 to get a Smart ED because I live in one of them. But I can't get a Honda
 FIT or Spark EV or Fiat 500e because those are California only. I
 presume Honda, Chevy and Fiat are buying ZEV credits to avoid having to
 make cars for us smaller states.

I think it would be incorrect to label the Smart ED as a compliance car, given 
that it is available here in Canada, well beyond the reach of CARB or other ZEV 
mandates ;^

My take on the compliance label is that any vehicle that is exclusively 
available in regions with a ZEV mandate is a compliance car in that it is (at 
least at this time) fairly clearly provided by the manufacturer only as a means 
of complying with a ZEV mandate.

As soon as the vehicle is offered anywhere that the manufacturer is not 
required to comply with a ZEV mandate, it is no longer a compliance car since 
the manufacturer is *voluntarily* making it available.

Cheers,

Roger.


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