EV Digest 4010
Topics covered in this issue include:
1) Re: One-Way Breaker
by <[EMAIL PROTECTED]>
2) RE: LED Head Lights?
by "Chris Tromley" <[EMAIL PROTECTED]>
3) Re: DIY Controller
by "Rich Rudman" <[EMAIL PROTECTED]>
4) Curtis 1231C-86XX Maximum Voltage
by "Bill Dennis" <[EMAIL PROTECTED]>
5) Re: Power supply question
by Lee Hart <[EMAIL PROTECTED]>
6) Well Balanced Old YTs
by "John Bryan" <[EMAIL PROTECTED]>
7) Re: S-10 Electric For Sale On Ebay (Long Range Self Transporting?)
by Jim Coate <[EMAIL PROTECTED]>
8) RE: High Power Zener
by "Don Cameron" <[EMAIL PROTECTED]>
9) RE: "Good wire" ?
by "Roger Stockton" <[EMAIL PROTECTED]>
10) Wire burnout on the Power Wheels
by Chris Zach <[EMAIL PROTECTED]>
11) Re: Power supply question
by [EMAIL PROTECTED]
12) RE: The Amazing Little Hawkers.
by "Roger Stockton" <[EMAIL PROTECTED]>
13) Re: High Power Zener
by Victor Tikhonov <[EMAIL PROTECTED]>
14) Re: The Amazing Little Hawkers.
by "Rich Rudman" <[EMAIL PROTECTED]>
15) Re: Wire burnout on the Power Wheels
by [EMAIL PROTECTED]
16) Re: KISS AC EV Drive System
by Lee Hart <[EMAIL PROTECTED]>
17) Re: KISS AC EV Drive System
by Lee Hart <[EMAIL PROTECTED]>
18) Re: One-Way Breaker
by Victor Tikhonov <[EMAIL PROTECTED]>
19) Re: The Amazing Little Hawkers.
by "Rich Rudman" <[EMAIL PROTECTED]>
20) Re: Blueprinting electric motors
by Victor Tikhonov <[EMAIL PROTECTED]>
21) Re: Curtis 1231C-86XX Maximum Voltage
by Frank Schmitt <[EMAIL PROTECTED]>
22) Re: LED Head Lights?
by Frank Schmitt <[EMAIL PROTECTED]>
23) Re: DIY Controller
by Victor Tikhonov <[EMAIL PROTECTED]>
--- Begin Message ---
> I was under the impression that in Doug's setup, it is not possible to
> connect the packs directly together - the main couple is the big diode
> feeding the controller from the lead-acid pack when the TS one sags
There is also a direct contactor connection for most efficient operation under
the TS low voltage condition of more than 1/3 discharged at warm temperature
(longer trips) or cold weather. This contactor should ideally (for general
public use) be under control by an intelligent electronics/microcontroller
circuit which is determining when to close the contact by looking at the
voltages, currents, etc.. However mine is manual for now.
> A more flexible way of doing this hybrid pack business, by the way, is
> to connect the controller to the lead-acid pack primarily, and build a
> simple current-mode-control PWM chopper to continuously supply 80A to
> the lead-acid pack, with an upper limit of 13.8V per block obviously.
Yes, this is a very good way of doing it. Doing it the wat I described has the
advantage that under light to moderate current drain and reasonably well
charged (just about all short trips and during the first part of longer ones),
the voltage will be a little higher and performance better. It is a
consideration for a low voltage EV like mine that are noticeably affected by
battery pack voltage.
> I also have 8 individual 3A power supplies which top up my AGM
> batteries from the mains while the TS pack is recharging.
My AGM pack is automatically charged at the same time as the TS pack from the
same charger - no worry of having a failure of one smaller charger, which
leaves one AGM module not charged & possible damage.
Regards,
Doug
--- End Message ---
--- Begin Message ---
Ryan Stotts wrote:
> The brake lights and turn signals can be easily converted to
> LED.
>
> This page says each LED at 12 volts DC pulls 10mA/Hr. They
> say they could make a cluster of up to 1000 LED's.
>
> http://www.theledlight.com/led-assemblies.html
>
> Has this been done? Is it viable? Would it be worth it if
> the cost for the LED conversion was low?
Hi Ryan,
I know little about LEDs. Years ago I actually knew a little about
lighting, but most of that knowledge is gone. (I'm the poster boy for the
"Use It or Lose It" campaign.)
What I do know is that there is a lot of hype surrounding LEDs. They can
indeed be very bright, which makes them suitable as markers or brake lights.
Intensity and volume are two different things, though. Headlights need to
throw *lots* of light to be useful. The same LED that you can see from a
mile away might be virtually useless in a flashlight for lighting a
footpath, for example. The website you posted lists "light output" in terms
of watts, which is completely meaningless. The correct term is (I believe)
candelas or milli-candelas. Until I see a comparison of LEDs to
incandescents in useable units, I will assume the LED marketers are still
relying on hype to sell product.
Here's an exercise for the reader. I'm not happy with the short life of the
two AA batteries in my Mini Mag Lite. I know LEDs would make the batteries
last *much* longer. Looking at the retail store level, I still haven't
found any flashlight or conversion kit that compares the LED cluster to the
original in units relating to genuine light output. Any leads?
Headlights also require a substantial amount of optical design effort to
properly shape the beam. It's workable when you have a single point source
of light at the filament. It's quite a different ball game with a 1000
individual LEDs.
Call me a skeptic, but someone's going to have to show me before I'd
consider LEDs as headlights. If equivalence in performance can actually be
achieved, the next step will be to see how they compare in price. :-O
Chris
--- End Message ---
--- Begin Message ---
Ok folks try test 9 in the down load section of my Website.
8 volts is 1600 amps on a warm Orbital.
at 1850 to 2000 amps my Graphite pile caught fire. This ended the tests.
The peak power we logged was 13.57Kw from a single Orbital, And we could
only load it down to 7.34 volts. There was more to be found.
So even John is wrong 8 volts is closer to 2000 amps than 1000.
http://www.manzanitamicro.com/processed%20orbital%209.xls
We don't know what White Zombie pulls the Orbs down two when doing a
parallel Jump to warp speed We are guessing 2500 to 3000 amp for about 3/4 a
second.
I would really like to Capture this data point.... Just for bragging rights.
----- Original Message -----
From: "John Wayland" <[EMAIL PROTECTED]>
To: <ev@listproc.sjsu.edu>
Sent: Thursday, January 06, 2005 9:34 PM
Subject: Re: DIY Controller
> Hello to All,
>
> Mike Barber wrote:
>
> > I base that number on using exide orbitals - I've read they weigh 40
lbs? If they were putting out 8V at 400A, you would need 48 batteries,
which would weigh 1920 lbs.
>
> Mike, your assumption of 8V at a just 400 amps is way off. It takes more
than twice that current level just to get them down to 9V. You're probably
closer to 1000 amps to get the super stiff Orbitals to go as low as 8V per
battery! When running just 20 Orbitals at 240V nominal and crossing the 1/4
mile mark at 101 mph, White Zombie was pulling three times your 400 amp
assumption at a whopping 1200 battery pack amps with the pack hanging at
155V, that's 7.5V per battery...awfully close to 8 volts. The Orbitals can
deliver ~2500 amps when kneeled down to 6V per battery.
>
> To back this up, Rudman said that at 2000 amp discharge levels, his test
Orbital was still above 7V. He would have tried to pull it lower, but the
battery blew up his load tester before he had the chance. That battery never
did fail, and has been used as the SLI under-hood battery in my Jeep Grand
Cherokee for more than a year now. Since first trying the Orbitals in the
Fall of 2004, at discharges of up to ~2500 amps, not a single one of these
batteries have failed.
>
> >You really can't get this kind of power without having a battery pack
that weighs more than around
> >2000 lbs. If they were putting out 8V at 400A, you
> >would need 48 batteries, which would weigh 1920 lbs.
>
> At just 400 amps, the batteries sag to about 11 volts (est.), so you'd
only need 34 of them. You're looking at a 1360 lb. pack, not 1920 lbs.
>
> >- correct me if I'm wrong please.
>
> Consider yourself corrected :-)
>
> See Ya.....John Wayland
>
>
>
>
--- End Message ---
--- Begin Message ---
I asked this question here a few days ago and even sent an Email to Curtis,
but haven't heard a response from either one. The 1231C-86XX can handle a
"nominal" voltage of 144V, but obviously the batteries charge up to a higher
voltage than that initially. So should I consider 13.2V * 12 = 158.V to be
the max, or something 14.4V * 12 = 172.8V to be the max? I'm trying to
determine the maximum equivalent number of TS cells at 4.25V that I could
use. Thanks.
Bill Dennis
--- End Message ---
--- Begin Message ---
[EMAIL PROTECTED] wrote:
> For my eLamby, I had planned on using a 1500watt power supply as
> my charger and as part of the hybrid section (i.e. -- fed by a
> portable generator). However, it is internally wired for 240V
> and when I open it up, there is no obvious ways to reroute the
> AC. It will put out the right voltage, but at very low current.
I'm not quite sure what you're saying here. Do you mean the power supply
is built for 240 volts AC input, and you want to use it with 120 volts
AC input?
If it was built for 1500 watts output, that's too high for a normal
120vac 15amp outlet. So, they would not have bothered to allow for
120vac input. At 120vac, it would draw over 20amps when you take its
efficiency and power factor into account.
You can trace out its AC input circuit. It probably has a noise filter,
inrush limiter, and then a bridge rectifier and big filter capacitor(s).
The rectifier and capacitor(s) could be rewired as a voltage doubler.
This will work with a 120vac input. Beware that you would have to rework
the filter and inrush limiter to deal with the doubled input current.
--
"Never doubt that the work of a small group of thoughtful, committed
citizens can change the world. Indeed, it's the only thing that ever
has!" -- Margaret Mead
--
Lee A. Hart 814 8th Ave N Sartell MN 56377 leeahart_at_earthlink.net
--- End Message ---
--- Begin Message ---
Madman Rudman said:
> That would give me 90 miles in Goldie... Up from the 10 she now gets....
I'm glad to hear that I'm not the only one with a 10 mile range!
The other day I went for a full discharge on my pack of 8+ year old
YellowTops. I didn't intend to run them down all the way, I just
wanted to go for a ride in the countryside.
I hadn't gone for my usual drive the week before, since Dave
(Battery Man) Hawkins and I hadn't gotten together for an electric lunch,
so it had been sitting off charge for almost 2 weeks and the battery
temperatures were probably in the 20's maybe even the teens. I know
my current warm weather capacity to be about 22 Ah, for a range of
around 25 miles, and I was pleased to get half of that at these
temperatures. The thing that amazed me was how the pack behaved
at the end of it's charge, which came after just 10 Ah under these
extreme conditions.
The voltage had been sagging all along, due to the extreme cold,
but coming up the final stretch the voltage started to sag a bit more and
I knew it was just about done. Once the resting voltage fell below nominal,
I was amazed to see it not recovering (which would be indicative of a
reversed cell regaining proper polarity). I got out of the car and went
straight to my known weakest battery and grabbed the known weakest
cell (the one I've reversed a few times over the years), and the cell was
freezing cold, along with all of the other cells I sampled. So the whole
pack had reached a full discharge at the same time, which I thought
was a pretty impressive state of balance under these conditions. It'll be
nice when things warm up and their capacity returns.
To get a feel for just how old these batteries are - subtract 8 years
from your age and think about how those were the good ole days.
...John
--- End Message ---
--- Begin Message ---
From what I gather, the various computer brains would get confused, and
there is no easy (or known???) way around it. This is similar to my
desire to add something like a PFC-20 as an opportunity charger for when
a regular 120 volt outlet is all that is available and/or don't feel
like lugging the magna beast along.
I've never touched one, but my impression is that the factory S-10 is a
great vehicle, provided you are always in range of the charger.
Now if someone does know how to poke at the brains and wants to share
that info ...
Lightning Ryan wrote:
So, since this is a PbA vehicle, could you simple tap into the pack
with your own charger? Would a PFC-20 or 30 keep up on the freeway?
I wonder if the stock BMS would get confused by bypassing it this way?
_________
Jim Coate
1970's Elec-Trak
1992 Chevy S-10 BEV
1997 Chevy S-10 NGV
http://www.eeevee.com
--- End Message ---
--- Begin Message ---
Would this make life any easier?
http://www.onsemi.com/pub/Collateral/MC33349-D.PDF
Appears as though they are 0.40 each, but may not handle the power or may
require expensive external components.
Victoria, BC, Canada
See the New Beetle EV Conversion Web Site at
www.cameronsoftware.com/ev/
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Lee Hart
Sent: January 7, 2005 11:33 AM
To: ev@listproc.sjsu.edu
Subject: Re: High Power Zener
Bill Dennis wrote:
> To protect a TS cell from over-voltage, can it be as simple as
> clamping a 1% 4.2V or 4.3V Zener dialog across the cell terminals?
Yes, in principle. But, real zeners aren't good enough. Zeners around 4.3v
have a very soft threshold, large variations between devices, and drift a
lot with temperature. For example a 1N5336 4.3v 5% 5w zener
draws:
1ma at 3.0v
25ma at 3.6v
110ma at 4.0v
290ma at 4.3v
550ma at 4.5v
1100ma at 4.7v
Note that it still draws 25ma at 3.6v; so it would run down a fully charged
battery just from sitting for weeks. And the clamping action is very soft,
and would let the cell go over 4.3v even with only 290ma of charging
current.
--
"Never doubt that the work of a small group of thoughtful, committed
citizens can change the world. Indeed, it's the only thing that ever has!"
-- Margaret Mead
--
Lee A. Hart 814 8th Ave N Sartell MN 56377 leeahart_at_earthlink.net
--- End Message ---
--- Begin Message ---
Lee Hart [mailto:[EMAIL PROTECTED] wrote:
> Your best assurance for quality wire is to look for "UL",
> "CSA", "CE", or other safety agency ratings right on the wire
> itself. These temperature and voltage ratings have been
> independently tested and confirmed.
Actually, I think you can safely scratch 'CE' from that list as use of
that symbol is by self-declaration (i.e. a manufacturer can put it on
his product because he believes he meets the requirements, or because he
wants others to have that impression, but there is no requirement for
him to have the product's compliance independantly tested or confirmed).
He does have to remove the symbol and gets his wrist slapped if he gets
caught...
Cheers,
Roger.
--- End Message ---
--- Begin Message ---
Drat. Apparently both kids on the commute to school and back were enough
to overload one of the wires on the Power Wheels jeep. The foot pedal
breaker did not trip, however the 40amp fuse at the battery did. However
before that it softened the insulation on the stock wiring.
Drat. So before I re-wire this, does anyone have any thoughts or
recommendations for a 12 volt electronic speed control? Must be able to
handle 40amps max.
Thanks!
Chris
--- End Message ---
--- Begin Message ---
> I'm not quite sure what you're saying here. Do you mean the power supply
> is built for 240 volts AC input, and you want to use it with 120 volts
> AC input?
>
> If it was built for 1500 watts output, that's too high for a normal
> 120vac 15amp outlet. So, they would not have bothered to allow for
> 120vac input. At 120vac, it would draw over 20amps when you take its
> efficiency and power factor into account.
>
PFC is suppose to be high, and while it is rated to 1500watts, it has an
adjustment for peak amps; the generator I have is rated 1000watts peak, so I
was going set it for 8A input, 60V output and whatever current it can give me.
If you run an unaltered 240V item on 120V, and it *does* have the correct
voltage output, what would you expect the output amps to run?
My command of electronics is not too deep, so rather than ruin a working 240V
power supply, I'm looking for another 48-60Vdc unit to handle
900-1000watt/120Vac inputs. Anyone got a surplus item in that range?
--- End Message ---
--- Begin Message ---
Joe Smalley [mailto:[EMAIL PROTECTED] wrote:
> This is where we disagree. If the charger turns down below a
> useful current when the first monoblock got full, the other
> monoblocks in the string WILL NOT get full. In order to get
> the bottom ones full, you need to put current into them. The
> full one will not let the charger put out meaningful current.
> To get the bottom ones to charge fully, the current has to
> come up. Without regulators, the full monoblock current is
> limited either by the recombination capability of the full
> battery.
I think that mostly what we disagree on is our definition of
'meaningful' current.
As long as *any* (OK, almost any ;^) current at all is passed through
the less full monoblocks, they will charge and will eventually become
full, but I agree totally that without regulators the amount of current
you can provide to the less full modules is limited by the recombination
capability of the full module.
> If you want to put more current through the string
> to reduce the charge time, a bypass path is necessary to
> prevent drying out the high battery.
Agreed. All I propose is that they are not essential to properly
charging an AGM when the shortest possible charge time is not a
priority.
> My experience is that it takes too long to achieve
> equalization without the shunt regulators. You very likely
> may have more patience than Madman Rudman.
I suspect you are correct ;^>
> It is a matter of opinion whether you want to blow off the
> excess energy equalizing a series string in a) the internal
> recombination or b) in shunt regulators. I have done battery
> packs both ways. I don't usually have the patience to do it
> the slow way, but sometimes I do. When I don't have the
> patience, I use regulators. Your opinion may be different.
Nope; we agree: if short charge time is the priority, then regs are a
solution.
> My experience is that an Orbital and an Optima click their
> pressure vents at under an amp. I don't like that. Your
> experience may be different.
Again, our experiences (mine not with Orbitals yet) concur. I also
don't like to hear my Optima's venting.
Just to muddy the waters, last night I pulled a neglected YT from under
my bench and put it on a bench supply to top it up. It has been sitting
for some months, and I recently discovered that it's resting voltage was
just 11.5V (ack!). Shortly after midnight, after several hours at 2A,
its voltage was up to 13.5V or so, so I adjusted the voltage limit on
the supply down to a "safe" 14.3V from the original 14.7V I'd set and
went to bed. At 6:30am I checked on it and found it sitting at 14.3V
and *well* under 2A (the analog meter showed no noticable current), and
venting profusely! Not clicking its vents, but a steady gentle hissing.
I disconnected the supply and then decided to measure what the current
was: 0.22A @ 14.1V. None of the cells were detectably warmer than
ambient (~10-15C) and about 2hrs after removing the supply the terminal
voltage had settled to 12.97V.
So, here is a YT that vents profusely at just 14.3V and <0.25A; regs set
to 14.5 or 14.7 or 14.8V wouldn't do a damn thing to protect this
battery and if set much lower than this you are suggesting that the
batteries would not be fully charged. It seems that with or without
regs, there will likely always be some monoblocks that are too far out
of line to be charged without some degree of abuse.
Cheers,
Roger.
--- End Message ---
--- Begin Message ---
Look closely at Zener's I-V curve and you'll realize why
this is a bad idea. Not to mention you can't do temp
compensation of clamped voltage and finding ~10W zeners.
Victor
--
'91 ACRX - something different.
Bill Dennis wrote:
To protect a TS cell from over-voltage, can it be as simple as clamping a 1%
4.2V or 4.3V Zener dialog across the cell terminals?
Bill Dennis
--- End Message ---
--- Begin Message ---
Joe is doing a good job of hasshing this out with you, I have been laying
low....
I am in no mood to fight.. but... you did pick on a few points that I feel I
have to defend...
----- Original Message -----
From: "Roger Stockton" <[EMAIL PROTECTED]>
To: <ev@listproc.sjsu.edu>
> Even if simpler voltage sensors were used which could only alert the
> charger that a monoblock had exceeded the safe maximum voltage, a
> reasonably intelligent algorithm would still result in all monoblocks
> fully charged. The undesirable behaviour you describe is due to the PFC
> charger's lack of intelligence.
It's not sporting to blame lack of hardware intelegence....instead of
the designer's lack of understanding...
The senario you are outlining is Reg protection without the bypass
capability. Sounds like what happens when you run loadless Regs without the
external loads hooked up.
Been there ....
The end result is the over voltaged regs shut the charger down... END of
charge. You just end up waiting for the Stiffest smallest Monoblock to have
to conduct all the current needed to fill the Largest
lowest state of charge battery in the string. Your end of charge point is
now locked up.
Granted that the Darned battery Salesmen have promised you 2 to 4 amps
of charge won't hurt thier batteries for extened periods of time at Gassing
voltage levels... You would think that a simple voltage feed back to the
charger is all that is needed.
GOD! I wish it really worked that way. Gee I could make Regs that don't
have to dissapate any heat. That product would be less than a square inch...
and cost me less than $10 to make.
>
> > With regulators installed on each monoblock, the 15.0 will be
> > clamped to ~14.5 to keep it from gassing excessively while
> > the other monoblocks continue charging at 3 amps. This allows
> > all the monoblocks to reach ~14.5 volts and to all be full
> > and to have a pack voltage of 290 volts.
>
> Tapering the current without regs will not prevent the other monoblocks
> from filling up, although it is true that they may not all reach at
> least 14.5V before the current has tapered to an unacceptably low level
> (from a charge duration perspective) in order to prevent the highest
> voltage module from exceeding the max safe level.
So Roger.... how many times have you charged a 10 Block string of AGM????
You seam to lack the experience that you need to see why I am laughing
at you so hard.
Even with solid voltage regulation on the entire string. Say 191 +- .5
volts. It is almost impossible to get all the batteries to rise above 14.8.
Some do some don't, and with out regs acouple never will.
If you install voltage sensors on all the regs, You will just slow the
charge process down even farther, But you will properly protect the
batteries.....
Regs hurry this a up a LOT.
Without some bypass current you get protection, without any Action to
solve the problem.
And of course these issues(the forces that tend to unequalize a string)
get aLOT worse when doing deep discharges,and with growing battery age.
>
> What you seem to be describing here (non-bypassed modules charging at
> 3A) is the constant current finish portion (or the very tail end of the
> absorption), such that the charger is pumping a constant 3A into the
> string and the active reg(s) are locked full on so that the bypassed
> modules are seeing *no* charge current.
Umm Really no current???? If you say so. But the battery continues to take
some charge current, Just what it wants, Not what the main charger is
stuffing into the whole string.
There are other mono blocks that are still accepting current. It's just that
the one with the Reg active... can't take as much as others can.
>
> > Please keep in mind two things are going on here: 1)The 3 amp
> > bypass is used for equalization. 2) The voltage sense is used
> > to allow safe fast charges. A monoblock can get in a lot of
> > trouble real quick at 60 amps.
>
> Yes, understood. My observation is that a simple voltage sense instead
> of a full-blown reg provides exactly the same safety, and that suitably
> intelligent charge algorithms can achieve full charge and equalisation
> at the expense of a longer charge duration.
Yea really long durations... like days....
Nice if you are doing emergency lighting and UPS work, Where you have
months on your hands.
Not so nice if your client is standing around twiddling his thumbs and
wants to get back to Work before dinner time.
>
> Cheers,
>
> Roger.
>
Are we making progress Roger???, or are you just going to argue some more?
Do you have a test pack???? Are you seeing the same things as I do????
--- End Message ---
--- Begin Message ---
> Drat. So before I re-wire this, does anyone have any thoughts or
> recommendations for a 12 volt electronic speed control? Must be able to
> handle 40amps max.
There are a few 6-15V kits on eBay:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=7126297700 -- rated 20A
continuous, so maybe the momentary peak is higher? This does have a higher
rating than the other kits I've seen. Would a different MOSFET be enough to
upgrade the current rating?
What's interesting is, when you go looking specifically for a 12V controller,
you don't get much, but there are tons of 24V units available, since this seems
to be the default level for electric wheelchairs.
--- End Message ---
--- Begin Message ---
[EMAIL PROTECTED] wrote:
> It sounds like you are considering manufacturing and selling
> systems like you just described. How would it be different
> from what is already available?
It should be a lot cheaper, and much easier to modify. It is equivalent
to our DC series motors and PWM controllers, where there is a lot of
flexibility on how you use it.
> You mention that it is AC, "simple", must use an automatic
> transmission, etc. Because of this, I assume it won't be
> considered high performance.
No, not at all! For example, the "Electrovairs" that GM built in 1966 (a
converted 1966 Corvair) had this setup. They had a 532vdc pack, simple
6-step SCR inverter, and 240vac 3-phase AC induction motor. They got
100kw out of it -- same as the EV-1! The Electrovairs were the same
size, same weight, same top speed, and same range as the EV-1!
Nothing stops you from using it with a manual transmission, or monster
motor and controller to get very high peak horsepower. Of course, then
it won't be as cheap.
--
"Never doubt that the work of a small group of thoughtful, committed
citizens can change the world. Indeed, it's the only thing that ever
has!" -- Margaret Mead
--
Lee A. Hart 814 8th Ave N Sartell MN 56377 leeahart_at_earthlink.net
--- End Message ---
--- Begin Message ---
Russ Kaufmann wrote:
> Lee Hart presents no nonsense ideas that are easy to understand
> and use the KISS (keep it simple) philosophy.
Thanks! And good to hear from you, Russ.
> About five years ago Lee posted a simplified AC drive system for an
> electric vehicle... use a rewound four pole induction motor, feed it
> with a six step inverter and use an automatic transmission.
Yes, I remember. This idea is based on an EV with AC drive that I built
around 1980. I basically took what I learned from this test vehicle, and
described what I would have tried next.
This EV was a scratch-built "jeep" sized vehicle. It weighed about 2400
lbs, was direct drive with a 5.17:1 differential driving the front
wheels, and had an 84v pack of golf cart batteries.
First, I tried a 36v 500a aircraft starter-generator and contactor
controller (from my previous EV, a 1974 Datsun pickup conversion).
Performance was worse; without the Datsun's 4-speed transmission,
accelleration was slower though top speed was about the same. The motor
was relatively inefficient, and needed a lot of cooling.
So, I tried an AC drive. I used an aircraft 120/208vac 400hz 15kw
3-phase alternator as a motor (mainly because it was cheap, and bolted
right on). The phase windings were reconnected for 40/70vac (it was a
6-pole machine). I built a 6-step SCR inverter, and experimented with a
number of schemes to control it (PWM, switching pack voltage with the
contactor controller, field control with the alternator's wound rotor,
etc.).
Here's what I learned:
- There was no fundamental difference between a DC separately excited
motor and a wound-rotor AC motor. Both had about the same torque
speed range and efficiency. Going transmissionless is hard for
either DC or AC; you just plain need a bigger motor and controller.
(2400 lbs with a 15kw motor won't work, AC or DC).
Conclusion: Next time, keep the transmission to allow a smaller
motor and controller.
- Having the field control winding (DC shunt field or AC wound rotor)
made it much easier to control, allowing far simpler controllers.
For example, easy regen and speed control. But, electronics is far
simpler today than it was in 1980.
Conclusion: Next time, try a simpler induction motor. This will
complicate the controller, but it's cheaper today.
- Aircraft generators and alternators are not very efficient. They
are optimized for high power-to-weight, not efficiency. They are
about 10% less efficient than normal ADC series motors or off-the-
shelf 60hz AC motors.
Conclusion: Next time, use a standard 60hz AC motor. Heavier, but
more efficient.
- Low pack voltage works fine. Currents were of course higher,
but not unreasonable. Lower pack voltages allow fewer batteries,
simplifying charging and maintenance.
Conclusion: Next time, pick the pack voltage based on cost, power,
range and other requirements. Don't let the motor/controller steer
the pack voltage. Rewire or rewind the motor for a suitable voltage.
I never got around to carrying out these ideas. My next EV went back to
a transmission with a GE series motor.
> This motor would be coupled to an automatic transmission with the
> torque converter.
I was thinking of a low-cost EV conversion. 90% of cars already have an
automatic transmission, so you might as well use it. Ideally, it would
have a locking torque converter; this gets rid of most of the
inefficiency penalty.
> With the use of a transmission... the inverter can a very simple
Exactly. You can of course add sophistication to improve performance and
efficiency, but it will work even if you don't.
> Starting frequency 20hz... idle, 600 RPM. Top speed 150hz... 4500 rpm.
Yes; this makes it simulate a normal ICE pretty well, to minimize the
need for transmission "reprogramming".
> For voltage control the battery pack would be connected in
> parallel/series using Albright contactors.
Yes. Remember that induction motor still work pretty well even if you
apply a voltage that is significantly "off" from optimum. There is a
maximum voltage above which it will saturate -- and a minimum voltage
below which you can't draw enough current for useful horsepower -- but
there is a *huge* range between them. Applying the wrong voltage
slightly lowers efficiency, and worsens the motor's power factor (harder
on the inverter).
The obvious way to try all this is to build a small version for a bike
or go-kart. Use something like a variable-speed belt type of CVT to
simulate the car's automatic transmission.
--
"Never doubt that the work of a small group of thoughtful, committed
citizens can change the world. Indeed, it's the only thing that ever
has!" -- Margaret Mead
--
Lee A. Hart 814 8th Ave N Sartell MN 56377 leeahart_at_earthlink.net
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--- Begin Message ---
Bill Dennis wrote:
...
For example, if the PbA pack
were fully charged to 158.4V (13.2 * 12) and the TS back were (for whatever
reason) discharged at 120V (3 * 40), then there'd be a 38.4V difference
between the packs. Assuming something like 5mOhm per 200Ah TS cell,
internal resistance would be .2 Ohms for the string. So the formula I =
38.4 / .2 yields an amperage of 192A into the string. Probably not fatal,
but I was just wondering if it was something to be guarded against, since
human errors do happen.
The fundamental flaw in your assumption is that the packs can be at
different voltages while connected in parallel which is impossible.
Precisely because low enough TS pack internal resistance, such
condition (38V difference or *any* difference for above reason)
will not occur as long as the packs are paralleled. As soon as
LiIon pack gets lower the current immediately flows into it keeping
it up.
I currently have such setup in ACRX (the caps play role of
"booster PbA pack". LiIons just can't sag below caps bank,
can they?
Victor
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ooooo!
There is a dawning of a light!!!
Why this happens needs to be solved my a Battery chemist.
But taking a long discharge on this battery, and fillin it up again... will
change the point at which it vents...
Things get funny after a long shelf life time. Regs help.... also being
less than totally abusive when bringing the Yts back on line helps.
This is the kind of abuse that EVers are really good at. Leave it parked
for months in the snow, light it up drain it, and then recharge it.
The concept of a "Commisioning charge" stolen from the NiCad curves comes to
mind. As a charge to bring them back from the Dead.
Venting BAD!!...let sit, discharge, try again .
And yes with 100 amps of charger.... I rarley sit and wait for a 2 amp
charger to get the job done slowly...
Speaking of that ... I better get a pass on the Orb pack this weekend.. I
have busted butt to get them into equalization... and the efforts are going
well. I don't want to loose that effort.
----- Original Message -----
From: "Roger Stockton" <[EMAIL PROTECTED]>
To: <ev@listproc.sjsu.edu>
Sent: Friday, January 07, 2005 12:58 PM
Subject: RE: The Amazing Little Hawkers.
> Joe Smalley [mailto:[EMAIL PROTECTED] wrote:
>
> > This is where we disagree. If the charger turns down below a
> > useful current when the first monoblock got full, the other
> > monoblocks in the string WILL NOT get full. In order to get
> > the bottom ones full, you need to put current into them. The
> > full one will not let the charger put out meaningful current.
> > To get the bottom ones to charge fully, the current has to
> > come up. Without regulators, the full monoblock current is
> > limited either by the recombination capability of the full
> > battery.
>
> I think that mostly what we disagree on is our definition of
> 'meaningful' current.
>
> As long as *any* (OK, almost any ;^) current at all is passed through
> the less full monoblocks, they will charge and will eventually become
> full, but I agree totally that without regulators the amount of current
> you can provide to the less full modules is limited by the recombination
> capability of the full module.
>
> > If you want to put more current through the string
> > to reduce the charge time, a bypass path is necessary to
> > prevent drying out the high battery.
>
> Agreed. All I propose is that they are not essential to properly
> charging an AGM when the shortest possible charge time is not a
> priority.
>
> > My experience is that it takes too long to achieve
> > equalization without the shunt regulators. You very likely
> > may have more patience than Madman Rudman.
>
> I suspect you are correct ;^>
>
> > It is a matter of opinion whether you want to blow off the
> > excess energy equalizing a series string in a) the internal
> > recombination or b) in shunt regulators. I have done battery
> > packs both ways. I don't usually have the patience to do it
> > the slow way, but sometimes I do. When I don't have the
> > patience, I use regulators. Your opinion may be different.
>
> Nope; we agree: if short charge time is the priority, then regs are a
> solution.
>
> > My experience is that an Orbital and an Optima click their
> > pressure vents at under an amp. I don't like that. Your
> > experience may be different.
>
> Again, our experiences (mine not with Orbitals yet) concur. I also
> don't like to hear my Optima's venting.
>
> Just to muddy the waters, last night I pulled a neglected YT from under
> my bench and put it on a bench supply to top it up. It has been sitting
> for some months, and I recently discovered that it's resting voltage was
> just 11.5V (ack!). Shortly after midnight, after several hours at 2A,
> its voltage was up to 13.5V or so, so I adjusted the voltage limit on
> the supply down to a "safe" 14.3V from the original 14.7V I'd set and
> went to bed. At 6:30am I checked on it and found it sitting at 14.3V
> and *well* under 2A (the analog meter showed no noticable current), and
> venting profusely! Not clicking its vents, but a steady gentle hissing.
> I disconnected the supply and then decided to measure what the current
> was: 0.22A @ 14.1V. None of the cells were detectably warmer than
> ambient (~10-15C) and about 2hrs after removing the supply the terminal
> voltage had settled to 12.97V.
>
> So, here is a YT that vents profusely at just 14.3V and <0.25A; regs set
> to 14.5 or 14.7 or 14.8V wouldn't do a damn thing to protect this
> battery and if set much lower than this you are suggesting that the
> batteries would not be fully charged. It seems that with or without
> regs, there will likely always be some monoblocks that are too far out
> of line to be charged without some degree of abuse.
>
> Cheers,
>
> Roger.
>
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Lee Hart wrote:
After endlessly telling them not to do this (and having them not believe
me), I've finally discovered the way to do it. I'll tell them, "Most
people use a screwdriver. You can also pound it in with a hammer, but it
won't work very well". Most kids will ignore the screwdriver and go for
the hammer. And the board splits or the screw bends. Now, after their
failure, there is a "teachable moment". They come back, and NOW they are
motivated to learn the right way to do it.
Often, to take two steps forward, you have to take one step back.
I agree, but most of the listers are not kids.
Also, wrecking 2 EVs to get one right is sort of wasteful.
Splitting 2 planks of wood before understanding not to pound
a screw in it is not a big loss for kind and fun way to learn too.
Have your kids purchase this planks of wood for $50 a piece
from you and they *will* listen to you before their first attempt.
That is what experiments with real EVs by adults often boil down to.
If I could wreck components for free, I'd do much more
experimentation :-)
Victor
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Mine regularly saw 180V without problems (right after an equalizing
charge).
But is the maximum-to-nominal-OCV ratio for LiIon all that different
from PbA? (I missed the first part of the discussion).
-Frank
On Jan 7, 2005, at 10:47, Bill Dennis wrote:
I asked this question here a few days ago and even sent an Email to
Curtis,
but haven't heard a response from either one. The 1231C-86XX can
handle a
"nominal" voltage of 144V, but obviously the batteries charge up to a
higher
voltage than that initially. So should I consider 13.2V * 12 = 158.V
to be
the max, or something 14.4V * 12 = 172.8V to be the max? I'm trying to
determine the maximum equivalent number of TS cells at 4.25V that I
could
use. Thanks.
Bill Dennis
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AEI (the SAE rag) regularly has articles about the progress of LED
lighting. They're currently quite competitive for situations where
you'd otherwise filter a white bulb down to one color (christmas
lights, traffic lights, brake lights), but for forward lighting they're
still a few years away from being incorporated into anything but a
concept car.
I think (like HID lights) you see a lag of about a year or two between
an OEM putting them in cars and the first reasonably affordable
aftermarket kits. Rolling your own might be feasible (especially
compared to HIDs :), but making it street legal probably isn't.
-Frank
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--- Begin Message ---
Mike Barber wrote:
I've been following this debate over AC motors very closely with much
interest. I am interested in building an AC EV. I initially learned
a lot from reading Victor's site - very well done, well documented
CRX conversion - nice job. I started thinking that I wanted my power
plant to be based on a siemens motor.
Thanks for the compliment - always nice to know that it inspires someone.
However, I started looking at the specs for these motors more
closely, and became a bit disenfranchised with them. It seems that
Siemens really designed these motors with large buses or boats in
mind, not smaller commuter BEVs. I say this because of the voltage
and current requirements.
18 kW 1PV5015WS12 is used in OEM Opel Astra Impulse:
http://www.ika.rwth-aachen.de/ueberuns/publikat/by0399b/index.htm
22 kW 1PV5104WS09 is used in VW City STROMer:
http://www.austinev.org/evalbum/160.html
15 kW (I believe) LH5118 is used in OEM Fiat Seisento:
http://www.austinev.org/evalbum/326.html
(this is conversion, but the size of the OEM car is the same
These motors hardly will move buses.
For example, the 1PV5135 motor has its
peak voltage at 380V, and its peak current at 400A. You really can't
get this kind of power without having a battery pack that weighs more
than around 2000 lbs - correct me if I'm wrong please.
OK, correcting. First, 5135WS14 indeed large than normally needed
for a car - it is OK for a van or heavy truck. But, people have used it
in a car: see Sheer's Accord for example:
http://www.austinev.org/evalbum/338.html
Second - 380V rating is maximum the motor will take without
braking down in insulation or other troubles - in reality it will
never see more than 250-280V rms. Siemens motors are very tough
and inverters are main limitation. So you can get about 78 mechanical
kW out of the motor due to electrical 100 kW input limit to the
inverter. The motors themselves listed on the web could do more
(for short duration) but never will have a chance due to inverter
limitation.
> I base that
number on using exide orbitals - I've read they weigh 40 lbs? If
they were putting out 8V at 400A, you would need 48 batteries, which
would weigh 1920 lbs.
Third - 400A is peak current, so RMS is 282A, so is max the inverter
can consume out of the battery. If you read the inverter spec,
282A is input battery current limit for the inverter.
Motor current is always higher than battery current. AC or DC
system.
Sure, you could probably use lithium ions to get more power
density... but you'd also have to get 400 amps out of them, so I
assume you'd have to parallel them up, and then you're talking about
a lot of money as well.
See above - 280A limit. Practically I don't see more than 150A
out of my battery. (Now, with the caps - no more than 40A unless
I'm on a long uphill)
For me, I would like to make my own controller. I realize this is
quite an effort, but I would consider that enjoyable. Since I can't
even buy these motors without buying the ~$4500 Siemens controller
with it, it doesn't make sense to buy these motors.
You can buy ACW80-4 alone. But the reason other motors are only
sold together with inverters is inverter is programmed for that
particular motor's parameters, and it is an OEM solution - whole
system works in a harmony as a matched "kit".
Of course if you perceive this advantage isn't worth the money,
welcome to experiment - as Lee suggested 60 Hz industrial
motors are good source to get your feet wet.
What Lee is talking about is very interesting, because you can design
the motor around your power source.
I personally think it is not the best approach. You must pick the power
you need/want for your vehicle (which already somewhat dictates
battery power without even considering drive system yet).
Then you pick a motor - the selection choices are not as good
as for batteries. You can fine-tune your pack by removing or
adding one, two or whatever batteries, changing their
capacity. You cannot do fine increments for the motors.
Same for controller/inverter. If you only insist on 240V no more
no less, your choices are very limited. Yes, more common 144V
offers more choices, but you see the point - it is easier to
manipulate with battery choice.
From talking to the guys at a local motor shop, they estimated a
rewinding fee of $1000. Assuming I could get the original 20hp
motor with a shorted stator for free, I could have a nice AC motor
matched to my lightweight battery pack for under $1500 (I'm
throwing some extra in there for getting a new balanced rotor with
nice bearings).
What is your lightweight battery pack?
Considering the Siemens motors cost in the
neighborhood of $3500, I'm still doing pretty good, and I'm having
someone else do the work - it's still just money at this point, not
endless hours of my time. Granted, they won't be totally enclosed
water cooled, but it sounds like it's pretty easy to stick a fan on
them and get good performance.
Yes, dollar wise you're doing pretty good. Especially now when
due to horrible state of US economy and currency exchange rates,
Siemens hardware cost near 50% more than it was in 2002.
When it recovers, situation will not be that bad.
Does what I'm saying have any major holes in it? Thanks again guys
for the good discussion.
No major holes. Just minor ones :-)
Victor
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