EV Digest 5652
Topics covered in this issue include:
1) Re: BMS poll
by Jeff Shanab <[EMAIL PROTECTED]>
2) RE: Aero shaft drive idea.
by "Garret Maki" <[EMAIL PROTECTED]>
3) Re: Measuring High Voltage
by [EMAIL PROTECTED]
4) Re: BMS poll
by "Mike Phillips" <[EMAIL PROTECTED]>
5) Re: BMS poll
by "Mike Phillips" <[EMAIL PROTECTED]>
6) A BMS definition (Re: BMS poll)
by "Mike Phillips" <[EMAIL PROTECTED]>
7) RE: Batt-Bridge monitor
by "Garret Maki" <[EMAIL PROTECTED]>
8) Re: "Who Killed the Electric Car" radio blurb tomorrow (Friday) morning on
CBC Radio One at 8:36am Central.
by "jmygann" <[EMAIL PROTECTED]>
9) Re: BMS poll
by Ralph Merwin <[EMAIL PROTECTED]>
10) RE: BMS poll
by Electro Automotive <[EMAIL PROTECTED]>
11) Re: AC output to rectifier
by Steve Condie <[EMAIL PROTECTED]>
12) Re: AC output to rectifier
by Lee Hart <[EMAIL PROTECTED]>
13) RE: BMS poll
by Steve Condie <[EMAIL PROTECTED]>
14) Re: Batt-Bridge monitor
by Lee Hart <[EMAIL PROTECTED]>
15) RE: AC output to rectifier
by "Roger Stockton" <[EMAIL PROTECTED]>
16) Re: BMS poll
by "Chris Brune" <[EMAIL PROTECTED]>
17) RE: BMS poll
by "Roger Stockton" <[EMAIL PROTECTED]>
18) RE: Trying to understand shunt regs
by "Roger Stockton" <[EMAIL PROTECTED]>
19) Re: BMS poll
by Jack Murray <[EMAIL PROTECTED]>
20) RE: BMS poll
by "Roger Stockton" <[EMAIL PROTECTED]>
21) Re: BMS poll
by "Mark Grasser" <[EMAIL PROTECTED]>
22) RE: BMS poll
by "Roger Stockton" <[EMAIL PROTECTED]>
23) A BMS definition (Re: BMS poll)
by "Mike Phillips" <[EMAIL PROTECTED]>
--- Begin Message ---
22 MK2B regulators on 24 Orbitals and a fluke meter for the last two.
The regs got wet and died an early death.
I think this would be a great category to add to the photo album right
after batteries and charger.
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--- Begin Message ---
How are you getting the needed gear reduction with the shaft drive
Shadow?
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Mike Ellis
Sent: Friday, July 14, 2006 9:26 AM
To: ev@listproc.sjsu.edu
Subject: Re: Aero shaft drive idea.
Has anyone ever done this but vertically, 90 degrees instead of 180?
I'm not saying it is necessarily a good idea, but it would look cool
and let people see the motor instead of covering it with batteries or
electronics.
-Mike
On 7/12/06, Lawrence Rhodes <[EMAIL PROTECTED]> wrote:
> I just had an idea I'd like to run by the list. A shaft drive takes
up room
> typically where the batteries normally go. A loss of battery storage.
Why
> not flip the shaft sending it out the back behind the rear wheel.
Make a
> trailing cone to house it and the supporting structure. You would get
aero
> advantage and more batteries where you need them. Lawrence Rhodes
>
>
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In a message dated 7/14/2006 3:20:03 P.M. Pacific Daylight Time,
[EMAIL PROTECTED] writes:
Hey :)
I am doing a little project involving a basic stamp. I am looking for a
simple and safe way to measure pack voltage and feed data to the basic
stamp. The E-meter uses a pre-scaler, is there any other way to do it?
Thanks for your help.
mm.
I use a V-F converter on each battery that is powered by the battery under
test. Each V-F converter is optically isolated and only draws about 6MA when
it is active. It is kind of a tricky circuit but has been in use for a couple
years without a problem. A basic Stamp does the monitoring.
Pat
--- End Message ---
--- Begin Message ---
Feel free to start your own poll.
Mike
--- In [EMAIL PROTECTED], Mike Chancey <[EMAIL PROTECTED]> wrote:
>
> Okay, can we get a better handle on all this? What is the point of
> this poll? What is the statical accuracy of the responses? The only
> true know numbers are count of subscribers to the EVDL and the count
> of responses to the poll. The number of subscribers has nothing to
> do with the number of EVs owned by EVDL members, so that is of no
> particular value. The number of responses only shows how many folks
> feel like responding. The differences of opinion on what defines a
> BMS further clouds the results. Add on most folks using flooded
> batteries and not being concerned about having a BMS or even
> answering the poll and what do you get? Statistically irrelevant
numbers.
>
> As far as I know nothing that fully fits the definition of a battery
> management system is available as an off the shelf plug and play
> product that could be fitted to most EVs. The only options are more
> limited devices such as the Rudman Regs or PowerCheq
> equalizers. Everything else is either handmade or part of an OEM
> system. So, what options does that give us? If the point of the
> discussion is most people aren't using a true BMS then I would have
> to say of course not, they can't get one.
>
> I would like to see such a product become available, but it would
> have a major headache for whoever developed and marketed it. The
> massive variation in component choices on most EV conversion is going
> to make it difficult to build something that works for everybody or
> even for most folks. Add to it the naturally frugal nature of many
> of us and the unknown payback of adding such a device and the chances
> of selling many seem even less likely. Such a system would have to
> have an obvious and measurable long term savings just to get any
> real interest. That is a pretty tall order.
>
> I think a more valid poll might be something like this:
>
> 1. Do you have an EV?
> 2. What kind of batteries do you use?
> 3. What kind of charger do you use?
> 4. Do you use any kind of individual battery charge
> monitoring, regulation, or balancing?
> 5. If so, what kind?
>
> FWIW, I cannot setup the code for a poll on the Album myself. Jerry
> might be able to, but he is not available at this time. I do suspect
> that adding a field for battery management/regulation to the Album
> entries might be of value.
>
> Thanks,
>
> Mike Chancey,
> '88 Civic EV
> Kansas City, Missouri
> EV Photo Album at: http://evalbum.com
> My Electric Car at: http://www.geocities.com/electric_honda
> Mid-America EAA chapter at: http://maeaa.org
> Join the EV List at: http://www.madkatz.com/ev/evlist.html
>
> In medio stat virtus - Virtue is in the moderate, not the extreme
> position. (Horace)
>
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--- Begin Message ---
I've rebuilt a bunch of them if you want help repairing them. I'd say
91% still running reg's count as a BMS ;)
Mike
--- In [EMAIL PROTECTED], Jeff Shanab <[EMAIL PROTECTED]> wrote:
>
> 22 MK2B regulators on 24 Orbitals and a fluke meter for the last two.
> The regs got wet and died an early death.
>
> I think this would be a great category to add to the photo album right
> after batteries and charger.
>
--- End Message ---
--- Begin Message ---
BMS = Battery Management System
Battery Monitoring System would be another interesting poll.
Since Zregs qualify as a BMS in this poll, then Rich's regulators and
Power Cheq's certainly do too.
Regulators/clampers are all that is required to qualify. One charger
per batt qualifies, even if mounted off board of the vehicle.
Mike
--- In [EMAIL PROTECTED], Mike Willmon <[EMAIL PROTECTED]> wrote:
>
> OK, I'll bite first. I'll validate for the query on the last thread
back who wondered if BMS was Battery Management System, it
> could also refer to Battery Monitoring System. The terms are vague
enough as they are and now they have the same
> acronym....anyway...moving on...
>
> If powercheqs and flybacks are disqualified because they do not
regulate absolute pack voltage how about in combination with a
> 2-Stage, IU, or "smart charger" that runs constant current up to the
maximum "Regulation" voltage and then hold there for a preset
> time interval and then shuts off? That seems to qualify, except
that if they do not communicate with the charger they cannot
> shut it off if one reg/balancer fails. This would seem to put Rich
Rudman's combination of PFC-xx charger and MKxRegs in the
> "BMS" category, correct?
>
> **sarcasm mode on - not to anyone in particular though-
> I think I have to go back and change my answer to the Poll then :-O
If these are what we're defining as a Battery Management
> System then I'm afraid I must not have one. I might even lose the
argument that more than 3% of EV drivers on this list have a
> BMS. And I would then have no right to argue that Fuel Cell
Vehicles are woefully inefficient because it either takes 4X the
> electricity to make clean hydrogen, or less of you make dirty
hydrogen, because hey, I'm not getting the most out of "managing" my
> pack. I do know however that even without a BMS on my pack, I'm
still operating way more efficiently than the FCV's you see
> driving all over town.
> **sarcasm mode off
>
> Mike,
> Anchorage, Ak.
>
> > -----Original Message-----
> > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
> > Behalf Of Victor Tikhonov
> > Sent: Friday, July 14, 2006 11:08 PM
> > To: [EMAIL PROTECTED]
> > Subject: A BMS definition (Re: BMS poll)
> >
> >
> > Mike Willmon wrote:
> > > Roger is right. BMS is only vaguely defined. This will no doubt
> > cause many and varied conclusions.
> >
> > Let me try to fill the void here.
> >
> > Suggested definition of a BMS (battery management system)
> >
> > The main functions of a BMS are:
> >
> > - To keep the battery (individual cells/batteries and so the
> > whole pack) going outside predefined limits (integration with
> > the charging hardware is mandatory)
> > - To keep individual cells/batteries at the same (or close)
> > SOC at all times, e.g. continuously "manage" them.
> > - To disconnect the pack from the charger or from the load
> > if preset alarm/pre-alarm conditions are met. (This can be
> > done gradually, in stages, etc. Point is such a function must
> > exist).
> >
> > /side note
> >
> > Clampers/shunt regulators which are active only at the end
> > of charge do not qualify because:
> >
> > a) they are typically only active at the end of charge
> > to prevent exceeding max voltage on a cell/battery
> > while allowing cells/batteries with lower voltage still
> > being charged. This is very useful feature, but different
> > class of hardware. Shunt type regulators:
> >
> > b) Have no idea about SOC of each cell/battery
> > c) Never have chance to work if cells/batteries are
> > purposely cycled in the middle of capacity range and for whatever
reason
> > never fully charged. This is not good for lead but allowed for
> > Lithium based battery. I use to cycle my pack between about
> > 40% and 80% SOC. Any shunt type regulators/clampers in this case
> > would be useless.
> >
> > /end of side note
> >
> > Nice to have but strictly speaking not necessary features are:
> >
> > a) Detailed visual feed back to the driver ("OK" idiot light may
> > be sufficient as long as the battery is being treated all right)
> > b) Control of the drive system
> > c) Data collection (for off line analysis) facility
> >
> > 'Course far from exhaustive list - there is no limit for
> > nice-to-have stuff. This won't impact the basic definition
> > of "management" though.
> >
> > Since balancing SOC is primary goal (however SOC is defined),
> > the SOC of each cell/battery has to be known at any time.
> > This pretty much mandates some sort of polling each cell/battery
> > by a central controller which then decides on the local activity.
> > If, for simplicity, cell/battery voltage is substituted for SOC,
> > simpler devices can be used to equalize voltages (flying capacitor,
> > powercheq type or hardware and Lee's balancer) - one may get away
> > even without communication bus if only adjacent voltages are compared
> > and acted upon.
> >
> > These devices still qualify for a BMS as long as voltages are being
> > compared and acted upon continuously (this disqualifies any type of
> > clampers) *AND* total pack voltage is held within limits (this last
> > requirement disqualifies powercheqs and flying caps schemes which
> > try to maintain the voltage delta between adjacent battery close to
> > zero while ignoring absolute value.
> >
> > Battery monitoring systems are qualifying as long as they include
> > a person observing data as a part of the system to act upon
conditions.
> > Since this is not guaranteed "management", such systems should
> > not really qualify for a real BMS. It is similar as trying to qualify
> > a variac charger + fluke meter as fine and flexible charger because
> > a person can keep observing and adjusting it to follow very
> > sophisticated profiles. Consistently. In reality this does not happen.
> >
> > Hopefully this clarifies common definition of a BMS.
> >
> > I'm sure there will be some improvements or fine point debate,
> > but this is basic info for comparison purposes.
> >
> > --
> > Victor
> > '91 ACRX - something different
> >
> >
> >
>
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--- Begin Message ---
Check out www.labjack.com too. It is a good small company here in
Colorado.
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Jamie Marshall (GAMES)
Sent: Thursday, April 21, 2005 2:28 PM
To: ev@listproc.sjsu.edu
Subject: RE: Batt-Bridge monitor
I'd like to avoid using a relay system because I want the isolation to
happen right at the battery, keeping traction voltage isolated to inside
the battery box. I'd be worried about a relay shorting out and frying
my PC (or frying me).
I'm looking at USB based low-cost DAQs like this:
http://www.measurementcomputing.com/pmd.html
-Jamie
--- End Message ---
--- Begin Message ---
Raging Grannies and "Who Killed the Electric Car
http://www.peninsularaginggrannies.org/
--- In [EMAIL PROTECTED], "Mike Ellis" <[EMAIL PROTECTED]> wrote:
>
> There will be a "Who Killed the Electric Car" radio blurb tomorrow
> (Friday) morning on CBC Radio One at 8:36am Central.
>
> http://www.cbc.ca/listen/index.html# for streaming audio.
>
> -Mike
>
--- End Message ---
--- Begin Message ---
Ralph Merwin writes:
>
> I have a Manzanita Micro Mk2B regulator on each of my 13 battery pairs,
> with the REGBUS connections networked to a PFC20 charger.
I'd like to ammend my description to include the Zilla controller as part
of the "BMS", since it has the ability to keep the pack voltage from going
below a setpoint while driving.
I also have the "live low-batt" signal from the Mk2B regulators brought up
to a LED on the dash, so I also can see if any individual battery is below
a setpoint. This feature is not complete though.
Ralph
--- End Message ---
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It's easy enough to find out from the list admin how many people are on
this list. So I thought a poll is appropriate to see how many have
something attached to each battery that is active in managing the
battery pack. One charger per battery counts. Having a fancy charger
alone does not count.
So how many folks on this last have bms on their battery pack?
You should also be asking what kind of batteries they are using. A
BMS is absolutely essential on some batteries, but not needed on others.
Shari Prange
Electro Automotive POB 1113 Felton CA 95018-1113 Telephone 831-429-1989
http://www.electroauto.com [EMAIL PROTECTED]
Electric Car Conversion Kits * Components * Books * Videos * Since 1979
--- End Message ---
--- Begin Message ---
James - thank you. I had suspected that what you were saying was true - that
the primary source of inefficientcy in the bad boy charger was "harmonic
distortion" I had never run across that term before now, however. Everything
I had read in my undisciplined meanderings blamed the problem on "Power
factor". As much as I read up on the 90 degree shift between voltage and
current waveforms causing bad power factor made sense but didn't seem to match
what I was observing - that the inefficiency was significantly less at high amp
draws than at the very low float level. So I described it as the problem
arising from "skimming the top of the voltage curve" - which is I think what
you have ID'd as "harmonic distortion" - the fact that the current is only
flowing in bursts when the peak voltage rises above the battery's resting
voltage level - 120 times per second here in the states.
As to what the Watt-a-meter measures when it gives a figure for "Power Factor"
- I don't know. Of course, my bad boys have the current flowing through a
transformer, too, before it's rectified. So I would assume that there's some
bona fide phase-shift power factor issues going on as well. But in any event
the result seems to be about right for the difference between the watts flowing
into my pack and the watts the Watt-a-meter show coming out of the wall socket.
Example: 7 amps going into the pack at 180 volts might register as 14 amps
at 120 volts from wall and a .75 power factor. (All numbers approximate.)
James Massey <[EMAIL PROTECTED]> wrote: At 09:29 PM 14/07/06 -0700, Steve
Condie wrote:
> Because you're just skimming the top of the voltage curve, and the
>power factor is horrible, you're putting a lot more stress on your
>components than the amperage delivered would ordinarily take. All of my
>components are rated for 20 amps, and I use a 20 amp outlet, but I have a
>15 amp circuit breaker in my charger. The most current I set my dim boy
>at is around 7 or 8 amps. At that amp draw I get about a 75% power
>factor, and my Watt-a-meter says I'm pulling over 14 amps out of the
>socket. At float the power factor drops into the 40's.
G'day all
Well Steve, there is something wrong with your meter descriptions. "pick
me, teacher" applies to me here, too, since this is something I've only
come to a good understanding of in the last few weeks due to a project we
are working on. "Bad-boy" chargers, in fact any device that just rectifies
the "mains" as the first thing it does (be it any form of charger, power
supply etc) has good power factor. What these devices have wrong is high
harmonic distortion. Power factor may be 0.97 but harmonic distortion may
exceed 40%.
What is the difference? well, power factor is a statement of leading or
lagging of the current being drawn relative to the voltage waveform.
Transformer chargers and motors draw current later than the voltage wave
that drives them, (and is why small generators have a "VA" rating as well
as a wattage rating).
Harmonic distortion is due to the current being drawn in spikes or pulses -
usually right on top of the voltage wave, so each voltage wave peak has a
current spike that is only limited by the voltage sag of the "mains". The
average current may be 10A, but the peaks may be 20A or more (I don't
actually have any firm figures as to the magnitude of the spikes). Matrix
filters are made that reduce the harmonic distortion to something below 8%,
but can cost a fair bit. A project we are looking at requires to have
harmonic filters added to variable-frequency drives, in order to meet the
electricity and backup generator suppliers' requirements.
The alternative to a matrix filter is an active 'front end' on the device,
to draw current in very small steps that closely follows the voltage wave.
Rich Rudmans' PFC series and other chargers that tout their "power factor
correction" feature are in fact not being technically correct in what it is
that makes their chargers better than a conventional switched-mode charger.
A conventional switched-mode charger should have good power factor - but
terrible harmonic distortion. Transformer chargers can have both bad power
factor and bad harmonic distortion. Rich Rudmans' PFC chargers are an
example that does both power factor correction AND greatly reduced harmonic
distortion due to the active 'front end'.
I don't know what your watt-a-meter is actually attempting to report to you.
I guess this will probably confuse, rather than help, but should stimulate
some discussion.
Regards
[Technik] James
---------------------------------
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Get on board. You're invited to try the new Yahoo! Mail Beta.
--- End Message ---
--- Begin Message ---
James Massey wrote:
> Well Steve, there is something wrong with your meter descriptions.
> "Bad-boy" chargers, in fact any device that just rectifies the
> "mains" as the first thing it does (be it any form of charger,
> power supply etc.) has good power factor. What these devices have
> wrong is high harmonic distortion. Power factor may be 0.97 but
> harmonic distortion may exceed 40%.
The textbook definition is power factor = real power / apparent power;
that is, PF = Watts / (Volts x Amps). Watts, volts, and amps must be the
*instantaneous* values at every point in the cycle, summed up over a
complete cycle. This is computationally intensive (best done with
special circuits or a computer), but it works for *any* waveform.
However, there are shortcuts. Until recently, almost all real-world
loads were made of simple resistors, capacitors, and inductors (light
bulbs, heaters, motors, transformers, capacitors, and the like). These
devices have no harmonic distortion; a sinusoidal AC voltage produces a
sinusoidal AC current. This allows a much simpler "working definition"
of power factor; PF = Volts x Amps x cos(a) where volts and amps are the
values indicated by normal meters, and cos(a) is the cosine of the phase
angle between volts and amps. The phase angle can be easily seen on an
oscilloscope, or measured with a simple circuit that looks at the time
between the zero-crossings of the volts and amps.
But this simplified definition does NOT work with switching power
supplies, or any device that does not draw a sinusoidal current.
Nowdays, switchers are so common that the old simplified definition of
power factor is all but useless.
A "bad boy" charger, like a switcher, does not draw a sinusoidal AC
current; it draws its AC current in pulses. Therefore, you have to use
the textbook definition of power factor to measure it.
--
Ring the bells that still can ring
Forget the perfect offering
There is a crack in everything
That's how the light gets in -- Leonard Cohen
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
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--- Begin Message ---
I see we've assembled the traditional EVList circular firing squad for this
question, as usual!
This is Mike's poll. He defined his terms adequately. He's curious to see how
many people are doing ***anything*** to provide individualized attention to
each of the batteries which compose their traction pack in order to prevent
individual batteries from becoming over- or under- charged during the charging
process. Period. Not if they're doing ***everything*** that anyone might
think was a good idea for their batteries, not if they're doing stuff for their
batteries when they're not being charged, not, well, not anything but what he
asked. Which is in itself an interesting question, and the answers to which
are illuminating, even if you're not going to get a statistically significant
data stream from the responding posts.
All the other stuff is interesting, too, but I suspect that we can define
ourselves into a smaller and smaller corner until the last guy with the most
wires connected to his batteries "wins", which doesn't strike me as very
productive...
Roger Stockton <[EMAIL PROTECTED]> wrote: Mike Phillips wrote:
> I thought a poll is appropriate to see how many have
> something attached to each battery that is active in
> managing the battery pack. One charger per battery
> counts. Having a fancy charger alone does not count.
>
> So how many folks on this last have bms on their battery pack?
I think the use of the term "BMS" in the context of this rather focused
poll is misleading at best.
You are not asking about a BMS, you are specifically polling to see how
many people are doing *something* to their batteries individually during
charge.
I would suggest that a *BMS* refers to a system that looks after the
batteries on both charge *and* discharge, not just on charge, and does
*not* have to specifically involve some sort of bypass regulation.
In this context, examples of systems that might be considered BMS's
include the Zivan Smoother and Lee Hart Balancer, and perhaps the
Powercheqs. Examples of systems that would not count as BMS's include
Lee's Zener regs, Rudman regs, or the use of individual chargers.
I think that unless the question is rephrased, the results of this poll
would most accurately be interpreted as revealing how many on the list
treat individual batteries differently during charge, or perhaps more
generously, how many are using some sort of *charge* management system
that treats individual batteries differently (as opposed to smart
chargers that may be just as effective (or more), but do not treat
individual batteries differently).
While the results of the poll may be interesting, I think they are not
particularly meaningful without having people also indicate if they are
running lead-acid packs or not, and if their lead-acid packs are VRLA
(gel or AGM) or not. It is fairly well recognised that flooded lead
acid batteries are fairly tolerant of abuse and can deliver rated life
without any BMS simply by not abusing them overly on charge or discharge
and providing regular maintenance. I would suggest that the vast
majority of those on this list are using flooded lead acid, and so a
poll whose results indicated that only 5% of the list considers
individual batteries while charging doesn't paint an accurate picture if
75% of the list are using batteries which don't actually benefit
significantly from such treatment.
Cheers,
Roger.
---------------------------------
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Get on board. You're invited to try the new Yahoo! Mail Beta.
--- End Message ---
--- Begin Message ---
Jamie Marshall wrote
> I'd like to avoid using a relay system because I want the isolation
> to happen right at the battery, keeping traction voltage isolated
> to inside the battery box. I'd be worried about a relay shorting
> out and frying my PC (or frying me).
I faced this dilemma, too. The problem is that all solid-state devices
normally fail SHORTED. Given the high voltages, high noise levels, and
difficult automotive environment, mechanical relays are actually
preferable to solid state switching devices.
You can get intrinsically-safe relays that are guaranteed not to fail
shorted. You can also use double-throw relays, wired so no shorts occur
even if multiple relays are turned on at once. Like this (view with a
fixed-width font):
+72v +60v +48v +36v +24v
| _____ | _____ | _____ | _____ | __...
| | | | | | | | | | | | | |
nc O O no | nc O O no | nc O O no | nc O O no | nc O O no
\ | \ | \ | \ | \
com O | com O | com O | com O | com O
| K1 |______| K2 |______| K3 |______| K4 |______| K5
|
+ --------- meter
NC, NO, and COM are the Normally Closed, Normally Open, and Common
contacts of the SPDT relays. The + meter lead can be switched to any
battery + by powering one relay (K1-Kn). But any relay contact can stick
open or weld closed, and there still won't be any shorts, no matter what
other relays are operated. And, diagnostics can tell you precisely WHICH
relay contact is stuck open or closed.
If you're concerned about life (relays wearing out), use reed relays;
they are good for millions of cycles. Or better still, mercury-wetted
reed relays, which have an indefinite switching life.
--
Ring the bells that still can ring
Forget the perfect offering
There is a crack in everything
That's how the light gets in -- Leonard Cohen
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
--- End Message ---
--- Begin Message ---
Lee Hart wrote:
> James Massey wrote:
> > Well Steve, there is something wrong with your meter descriptions.
> > "Bad-boy" chargers, in fact any device that just rectifies the
> > "mains" as the first thing it does (be it any form of charger,
> > power supply etc.) has good power factor. What these devices have
> > wrong is high harmonic distortion. Power factor may be 0.97 but
> > harmonic distortion may exceed 40%.
>
> The textbook definition is power factor = real power / apparent power;
> that is, PF = Watts / (Volts x Amps).
> A "bad boy" charger, like a switcher, does not draw a sinusoidal AC
> current; it draws its AC current in pulses. Therefore, you have to use
> the textbook definition of power factor to measure it.
If I may summarise Lee's point here; power factor includes the effects
of both phase shift *and* harmonic distortion. You will not measure a
PF of 0.97 with any device that just rectifies the AC mains as the first
thing it does (unless it includes some form of power factor correction)
because the rectifier is usually followed by capacitors and so current
from the line is drawn in very brief high current spikes right at the
peak of the AC line voltage. This is exactly the case with a bad boy
charger (the battery is the capacitor), and is why we typically see 40
or 50A rectifiers being required in a bad boy that is only capable of
delivering 15-20A at best.
Without some form of power factor correction, power supplies, chargers,
etc. typically exhibit a best case PF or about 0.75-0.80 at full output.
PF typically tends to worsen at less thatn full output. The 0.4 value
that Steve referred to is not uncommon.
Cheers,
Roger.
--- End Message ---
--- Begin Message ---
Hi,
I'm using individual battery chargers on Orbitals.
Chargers are Soneil 5A chargers.
Regards,
Chris Brune
--- End Message ---
--- Begin Message ---
Steve Condie wrote:
> This is Mike's poll. He defined his terms adequately.
"BMS" is not *his* term to define. Purporting to poll the percentage of
EVDLers using some form of BMS while using this established term to
refer to something completely different results in meaningless and
misleading results.
> He's curious to see how many people are doing
> ***anything*** to provide individualized attention
> to each of the batteries which compose their traction
> pack in order to prevent individual batteries from
> becoming over- or under- charged during the charging
> process. Period.
Agreed. Problem is that most of us seem to agree that "BMS" is not the
appropriate term for describing such a *charging only* system (or
scheme).
> All the other stuff is interesting, too, but I suspect that
> we can define ourselves into a smaller and smaller corner
> until the last guy with the most wires connected to his
> batteries "wins", which doesn't strike me as very productive...
Actually, I think the guy with the fewest wires connected wins, but I
digress ;^>
My concern is that Mike asked the question because he was interested in
getting some sort of useful information in response, but the question is
*not* related to BMS in the traditional, more-or-less established
meaning of the term so the use of that term in the subject line and in
the original query will be a source of confusion and will be misleading
to anyone who stumbles across the EVDL archives in the following months
and years.
Because of the difference between what BMS means in conventional usage
and the question that Mike asked, it is not even clear if he really
wants to know who is using BMS or just who is providing some sort of
individual treatment to their batteries while charging.
I don't see how Mike can get useful information from the poll if people
are basically being asked to indicate if they are using something with
their batteries that they *think* might be considered to be a form of
battery management, but if this doesn't bother him enough for him to
rephrase his poll more precisely I'm certainly not going to lose sleep
over it ;^>
Cheers,
Roger.
--- End Message ---
--- Begin Message ---
Danny Miller wrote:
> Whoops, missed Roger's sarcastic element on the first
> read.... ok explaining the basic lead-acid charging
> algorithm to a guy who builds them wasn't really called
> for.
No problem ;^>
Thing is, what you described in the first place was an IU algorithm
where the constant voltage phase is at a lower (float) level than the
termination setpoint for the constant curent phase.
What you've followed up with is a description of the more traditional
IUI (or IU1U2) algorithm which differs notably in that the voltage is
held at the bulk termination setpoint until the current tapers to some
low level before proceeding to the third and final phase.
You described the original IU algorithm as the "ideal" PbA algorithm,
and noted specifically that it did *not* include holding the voltage at
the bulk termination setpoint until the current tapers off.
I am genuinely curious about the reference to this as the "ideal" PbA
algorithm, and to the elimination of the usual absorption/acceptance
phase.
Cheers,
Roger.
--- End Message ---
--- Begin Message ---
Mike, i'd agree with all, and add even more emphatically that it would
make sense to have such a poll taken on a website.
Jack
Mike Chancey wrote:
Okay, can we get a better handle on all this? What is the point of this
poll? What is the statical accuracy of the responses? The only true
know numbers are count of subscribers to the EVDL and the count of
responses to the poll. The number of subscribers has nothing to do with
the number of EVs owned by EVDL members, so that is of no particular
value. The number of responses only shows how many folks feel like
responding. The differences of opinion on what defines a BMS further
clouds the results. Add on most folks using flooded batteries and not
being concerned about having a BMS or even answering the poll and what
do you get? Statistically irrelevant numbers.
As far as I know nothing that fully fits the definition of a battery
management system is available as an off the shelf plug and play product
that could be fitted to most EVs. The only options are more limited
devices such as the Rudman Regs or PowerCheq equalizers. Everything
else is either handmade or part of an OEM system. So, what options does
that give us? If the point of the discussion is most people aren't
using a true BMS then I would have to say of course not, they can't get
one.
I would like to see such a product become available, but it would have a
major headache for whoever developed and marketed it. The massive
variation in component choices on most EV conversion is going to make it
difficult to build something that works for everybody or even for most
folks. Add to it the naturally frugal nature of many of us and the
unknown payback of adding such a device and the chances of selling many
seem even less likely. Such a system would have to have an obvious and
measurable long term savings just to get any real interest. That is a
pretty tall order.
I think a more valid poll might be something like this:
1. Do you have an EV?
2. What kind of batteries do you use?
3. What kind of charger do you use?
4. Do you use any kind of individual battery charge
monitoring, regulation, or balancing?
5. If so, what kind?
FWIW, I cannot setup the code for a poll on the Album myself. Jerry
might be able to, but he is not available at this time. I do suspect
that adding a field for battery management/regulation to the Album
entries might be of value.
Thanks,
Mike Chancey,
'88 Civic EV
Kansas City, Missouri
EV Photo Album at: http://evalbum.com
My Electric Car at: http://www.geocities.com/electric_honda
Mid-America EAA chapter at: http://maeaa.org
Join the EV List at: http://www.madkatz.com/ev/evlist.html
In medio stat virtus - Virtue is in the moderate, not the extreme
position. (Horace)
--- End Message ---
--- Begin Message ---
Christopher Zach wrote:
> I think you're picking at the details a bit hard here.
> What Mike is asking is how many people use some sort
> of active devices to manage the charging of batteries
> in strings.
You may be right. I too think this is what Mike is asking, but the
implication that he *might* be asking about a BMS instead causes some
uncertainty. I was just pointing this out so that Mike could rephrase
his poll to ensure that people are answering the question he wanted
answered and so that people who read the EVDL archives in the future
won't be mislead by the BMS references in this thread to misinterpret
the results of the poll as indicative of actual BMS usage by EVDLers.
> I've tried it the other way with a really smart charger
> and temp sensors; it doesn't work on AGMs. It does
> however work fine on flooded Pb and flooded NiCD
> batteries.
Don't take this the wong way, but whatever you tried may not have worked
with your particular charger and your particular batteries, in your
particular system, but that does not mean that you cannot charge *other*
AGMs without regs using some other charger. It may even be the case
that your AGMs could be charged without regs with a different charger
(or even the same one), but your system configuration is at fault.
For instance, we know for a fact that John Wayland has managed to get
respectably long life from his Optima AGMs despite not using regs or
even particularly smart chargers (I'm not including his knowledgable
supervision as part of the charger intelligence ;^)
> The Lee zeners aren't perfect, but they are way way way better than
> nothing.
Absolutely! I did not mean to suggest that all of these sorts of things
aren't potentially beneficial, just that they don't constitute a BMS
since they are only active during [part of] charging.
Cheers,
Roger.
--- End Message ---
--- Begin Message ---
WOW,
Roger, BMS may not be his term, didn't know he was defineing it. Wether the
reply he is getting is to your liking or not is also not yours to call on.
If he gets what he wants out of his survey is all that is important.
Where's a mail list cop when you need one, gees leave the guy alone.
You know, the ICE list I belong to is A LOT more civil then this one, you
guys really do a dis-service to yourselves.
Mark Grasser
78 #358
BIG REDs
http://members.rennlist.com/mgrasser
----- Original Message -----
From: "Roger Stockton" <[EMAIL PROTECTED]>
To: <ev@listproc.sjsu.edu>
Sent: Saturday, July 15, 2006 1:14 PM
Subject: RE: BMS poll
Steve Condie wrote:
This is Mike's poll. He defined his terms adequately.
"BMS" is not *his* term to define. Purporting to poll the percentage of
EVDLers using some form of BMS while using this established term to
refer to something completely different results in meaningless and
misleading results.
He's curious to see how many people are doing
***anything*** to provide individualized attention
to each of the batteries which compose their traction
pack in order to prevent individual batteries from
becoming over- or under- charged during the charging
process. Period.
Agreed. Problem is that most of us seem to agree that "BMS" is not the
appropriate term for describing such a *charging only* system (or
scheme).
All the other stuff is interesting, too, but I suspect that
we can define ourselves into a smaller and smaller corner
until the last guy with the most wires connected to his
batteries "wins", which doesn't strike me as very productive...
Actually, I think the guy with the fewest wires connected wins, but I
digress ;^>
My concern is that Mike asked the question because he was interested in
getting some sort of useful information in response, but the question is
*not* related to BMS in the traditional, more-or-less established
meaning of the term so the use of that term in the subject line and in
the original query will be a source of confusion and will be misleading
to anyone who stumbles across the EVDL archives in the following months
and years.
Because of the difference between what BMS means in conventional usage
and the question that Mike asked, it is not even clear if he really
wants to know who is using BMS or just who is providing some sort of
individual treatment to their batteries while charging.
I don't see how Mike can get useful information from the poll if people
are basically being asked to indicate if they are using something with
their batteries that they *think* might be considered to be a form of
battery management, but if this doesn't bother him enough for him to
rephrase his poll more precisely I'm certainly not going to lose sleep
over it ;^>
Cheers,
Roger.
--- End Message ---
--- Begin Message ---
Mike Willmon wrote:
> For example read Roland Wiench's post with this subject: "I
> have none, after 5 years, 30 of my T-145's are still in with 0.02
> volts of each other with over 20 in the 0.01 volt range..."
This is an excellent example of the questionable value of this poll.
Roland has flooded GC batteries, which are known to not be especially
dependant upon individual attention during charging. He has also
described his typical usage as involving *very* short drives of
something like 2-5mi total per day. With this sort of very shallow
cycling his batteries would likely provide years of service even if
moderately abused!
> I wonder if Mike Chancey could work a Poll section onto the
> EVAlbum front page? Or make use of the database now built into the
> EVAlbum listings?
I think the suggestion of adding a BMS field to the EVAlbum entries may
be the most effective way to collect/access this sor tof information.
Cheers,
Roger.
--- End Message ---
--- Begin Message ---
Good job Victor.
Roger, this is where BMS definitions can be discussed and defined.
Mike
--- In [EMAIL PROTECTED], Victor Tikhonov <[EMAIL PROTECTED]> wrote:
>
> Mike Willmon wrote:
> > Roger is right. BMS is only vaguely defined. This will no doubt
> cause many and varied conclusions.
>
> Let me try to fill the void here.
>
> Suggested definition of a BMS (battery management system)
>
> The main functions of a BMS are:
>
> - To keep the battery (individual cells/batteries and so the
> whole pack) going outside predefined limits (integration with
> the charging hardware is mandatory)
> - To keep individual cells/batteries at the same (or close)
> SOC at all times, e.g. continuously "manage" them.
> - To disconnect the pack from the charger or from the load
> if preset alarm/pre-alarm conditions are met. (This can be
> done gradually, in stages, etc. Point is such a function must
> exist).
>
> /side note
>
> Clampers/shunt regulators which are active only at the end
> of charge do not qualify because:
>
> a) they are typically only active at the end of charge
> to prevent exceeding max voltage on a cell/battery
> while allowing cells/batteries with lower voltage still
> being charged. This is very useful feature, but different
> class of hardware. Shunt type regulators:
>
> b) Have no idea about SOC of each cell/battery
> c) Never have chance to work if cells/batteries are
> purposely cycled in the middle of capacity range and for whatever
reason
> never fully charged. This is not good for lead but allowed for
> Lithium based battery. I use to cycle my pack between about
> 40% and 80% SOC. Any shunt type regulators/clampers in this case
> would be useless.
>
> /end of side note
>
> Nice to have but strictly speaking not necessary features are:
>
> a) Detailed visual feed back to the driver ("OK" idiot light may
> be sufficient as long as the battery is being treated all right)
> b) Control of the drive system
> c) Data collection (for off line analysis) facility
>
> 'Course far from exhaustive list - there is no limit for
> nice-to-have stuff. This won't impact the basic definition
> of "management" though.
>
> Since balancing SOC is primary goal (however SOC is defined),
> the SOC of each cell/battery has to be known at any time.
> This pretty much mandates some sort of polling each cell/battery
> by a central controller which then decides on the local activity.
> If, for simplicity, cell/battery voltage is substituted for SOC,
> simpler devices can be used to equalize voltages (flying capacitor,
> powercheq type or hardware and Lee's balancer) - one may get away
> even without communication bus if only adjacent voltages are compared
> and acted upon.
>
> These devices still qualify for a BMS as long as voltages are being
> compared and acted upon continuously (this disqualifies any type of
> clampers) *AND* total pack voltage is held within limits (this last
> requirement disqualifies powercheqs and flying caps schemes which
> try to maintain the voltage delta between adjacent battery close to
> zero while ignoring absolute value.
>
> Battery monitoring systems are qualifying as long as they include
> a person observing data as a part of the system to act upon conditions.
> Since this is not guaranteed "management", such systems should
> not really qualify for a real BMS. It is similar as trying to qualify
> a variac charger + fluke meter as fine and flexible charger because
> a person can keep observing and adjusting it to follow very
> sophisticated profiles. Consistently. In reality this does not happen.
>
> Hopefully this clarifies common definition of a BMS.
>
> I'm sure there will be some improvements or fine point debate,
> but this is basic info for comparison purposes.
>
> --
> Victor
> '91 ACRX - something different
>
--- End Message ---
