EV Digest 2845
Topics covered in this issue include:
1) Re: Starting torque
by Seth <[EMAIL PROTECTED]>
2) Re: Li Ion Series Resistance
by "Chris Brune" <[EMAIL PROTECTED]>
3) RE: DC to AC
by "Mark Fowler" <[EMAIL PROTECTED]>
4) Re: Why did the Optimas explode?
by Sheer Pullen <[EMAIL PROTECTED]>
5) Re: Why did the Optimas explode?
by [EMAIL PROTECTED]
6) Re: Why did the Optimas explode?
by Michael Hoskinson <[EMAIL PROTECTED]>
7) Re: DC to AC
by "1sclunn" <[EMAIL PROTECTED]>
8) Re: EV on eBay/factory conversion.
by "1sclunn" <[EMAIL PROTECTED]>
9) Re: EV on eBay/factory conversion.
by Sam <[EMAIL PROTECTED]>
10) Re: !958 Chevy Truck Conversion
by "1sclunn" <[EMAIL PROTECTED]>
11) TOYOTA STORY
by "Lawrence Rhodes" <[EMAIL PROTECTED]>
12) Tropica battery pictures
by [EMAIL PROTECTED]
13) Re: 72V dc/dc
by "Lawrence Rhodes" <[EMAIL PROTECTED]>
14) Re: 72V dc/dc
by "Lawrence Rhodes" <[EMAIL PROTECTED]>
15) AC vs DC (or boy have I had too much coffee)
by Jeff Shanab <[EMAIL PROTECTED]>
16) Re: DC to AC
by Lee Hart <[EMAIL PROTECTED]>
17) Re: Li ion Cooling (Was: Li Ion Series Resistance)
by Lee Hart <[EMAIL PROTECTED]>
18) Re: Starting torque
by Lee Hart <[EMAIL PROTECTED]>
19) RE: Li ion Cooling (Was: Li Ion Series Resistance)
by "Bryan Avery" <[EMAIL PROTECTED]>
20) Re: 72V dc/dc
by "garry" <[EMAIL PROTECTED]>
21) A new EV begins
by "garry" <[EMAIL PROTECTED]>
22) RE: 1958 Chevy Truck Conversion
by "Pestka, Dennis J" <[EMAIL PROTECTED]>
23) Re: DC to AC
by "Mark Hanson" <[EMAIL PROTECTED]>
24) Re: AC vs DC (or boy have I had too much coffee)
by Peter VanDerWal <[EMAIL PROTECTED]>
--- Begin Message ---
I think it has something to do with needing three 2000amp half bridges
instead of one, for starters. And needing to know how to put it to work.
Seems like even people like me can do modest, crude power (200A)for a
buck converter for a series or PM brush motor. But asynchronous AC... I
hear about space vector, third harmonic, eigen this or that and the
other. So there is both a learning curve (the "lab coat" guys, see
below) and a real price penalty on power silicon which is expensive at
high current increments. At least in my opinion.
more comments inserted below...
Victor Tikhonov wrote:
>
> That was stock street EV1 (same motor/inverter/battery?), just
> different gearing, and Mazda made for drag racing. What do you expect?
>
> It might have been fun experiment to watch, but this outcome was easy
> to predict ahead of time. And so this example really proves nothing in
> AC vs. DC arena. It only proved that this particular EV1 was worse
> than this particular Mazda, which, again, was obvious to begin with.
>
> This is not to say one is better than other, we don't know until
> someone does fair comparison. And, just because no one did it
> yet (AC is new, expensive, whatever reason), doesn't mean that
> technically other technology is better by default.
>
> So of course DC still rules, but I believe it's because of vast
> traditional past DC experience and no one seriously bothered yet to
> try to do it differently. Time will tell.
>
now I know Rich is allergic to white lab coats ;-), but they want torque
also. It just isn't as simple as more amps. But stall torque, and
maxiumum stall torque per transistor to make the "electronic
transmission" a reality is a very important goal, from a marketability
point and saving costs on the controller. "We haven't figured out the
motor math yet, so we just use 800 amp modules for 35kW at 336VDC and
hey, 750 watt-hours per mile isn't bad for a compact car" isn't going to
cut it at review time for *that* motor engineer.
> > ><Rich Rudman wrote>
> > > The guys with the degrees and the white lab coats miss this point rather
> > > badly.
> > > The launch end of the track is were you spend most of your time, that's
> > > why you want to it leave as fast as you can.
> > >
> > > And with the proper tire and suspension geometry, you launch instead of
> > > burn rubber. Even with a single tire you can get a setup that won't spin
> > > out.
> > > The burn off is to heat the rubber so it sticks. Not just to measure our
> > > Manhood by.
> > >
> > > It's harder to make up lost time on the fast end it takes more Hp. Get
> > > the lauch right, and keep the action going all the way down the strip is
> > > the target.
> > >
> > > Most of us EVers who spend a weekend or two a year racing soon realize
> > > that the EV motors as we know and use them go to sleep at about 4000 to
> > > 5000 rpm. But off the line with a Series wound DC motor we can't get
> > > enough traction to use the full power that we do make. Spin Stick... Bog
> > > , Shift. AC offers full power from one line to the other, with enough
> > > RPM range to get rid of the transmission.
> > > With a light enough Chassis and years of effort, you can get a Dc motor
> > > to run the length of the track and still yank it sideways at the MPH
> > > trap. There is only ONE that has proven this.
> > >
> > > --
> > > Rich Rudman
\
<unsnip>
My two Newton-metres worth...
--
[EMAIL PROTECTED]
--- End Message ---
--- Begin Message ---
> > I did do a series discharge of four cells today at 27A. One cell
> > had a temp rise of about 30C. The whole block gets pretty warm.
>
> Yes, I'm seeing that too. Notice that the terminal bolts get hotter yet,
> indicating that the internal temperature is even higher.
BTW, all my temperature measurements are at the terminals. I use a
thermocouple embedded in ring terminal. I agree that the terminals seem
warmer than the cases, at least to my calibrated fingers :)
Chris Brune
--- End Message ---
--- Begin Message ---
Hi Lee (and list),
I'm pretty much just contemplating at this stage.
I was hoping to use it to initially cycle my Li-Ions by running things like a heater
or air-con.
(You know, do something useful with the power, rather than just heating up a barrel of
water or driving sedately around the block 1000 times)
After that, of course, the sky would be the limit - portable mains power without
needing a generator :-)
So, no, I hadn't given any thought to how smooth the waveform would have to be.
I'd imagine that a big chunky square wave would be fine for heaters and power tools,
but a smoother sine wave would be required for more delicate electronics and sound
equipment.
How precise does the frequency have to be? No idea. I said 50Hz because that's what
comes out of our power points around here.
What sort of power level? Fairly large. I'd like to get the full 2400W that Australian
standard 10A circuits supply.
Hence not wanting to drop down to 12V DC to invert back up to 240V AC.
Mark
--- End Message ---
--- Begin Message ---
This makes it sound kind of like a hydrogen explosion - i.e. a tiny spark
from a opening switch makes the battery go *boom*?
Were both cars in question vented? Passive or active (with a fan)?
On Tue, 10 Jun 2003 [EMAIL PROTECTED] wrote:
> I had one (1) twelve volt Douglas Marine deep cycle 105 amphr battery
> explode one night as I shut off the DC circuit breakers between the
> battery pack and controller. It was one of 20 batteries in series for a
> 240 volt DC battery pack to run a 230 volt DC 10 hp Westinghouse elevator
> motor in my father's 1967 Ford Window Van. Douglas just said it was a
> manufacturing defect, replaced the battery under warranty, and said I
> would not be talking to them if it was not an isolated manufacturing
> defect because otherwise all 20 would have blown up in my face.
> Menlo Park III,
> Bill
>
> On Tue, 10 Jun 2003 17:59:33 -0600 Michael Hoskinson <[EMAIL PROTECTED]>
> writes:
> > My friend Ken Norwick had some nasty experiences with YT's and if
> > anybody can explain what he might have done wrong it would
> > probably be educational for all. Ken is not a member of the
> > list. About a year ago he switched to flooded 8 volt USB
> > batteries and has had no trouble with them.
> >
> > His car is a 96 Saturn with a 9" ADC motor and Raptor 600 amp
> > controller. He was using a Zivan NG3 charger. On 3 occasions he
> > had an Optima explode in a cloud of acid mist and loud noise.
> > These experiences had the undesirable side effect of reducing his
> > wife's tolerance of the project and any future EV efforts. For
> > some reason, she won't drive the car either.
> >
> > As Ken described it, on each occasion the pack had recently come
> > off charge and he was within a block or two of starting out,
> > drawing less than full amps (he was not specific about the amps,
> > but I'd bet it was considerably less than, say Blue Meanie would
> > pull on an average demo run). Then BANG!, cloud of acid steam
> > and one of his batteries has no top. He told me that all of his
> > connections were good and it was not a question of melted posts.
> >
> > Can anybody speculate on the cause of such a thing? I'm thinking
> > perhaps overcharging built up pressure in the batteries and extra
> > warming from current draw was enough to cause the explosion. But
> > what do I know? If there are questions I should be asking Ken,
> > please let me know.
> >
> > Mike Hoskinson
> > ev-less in Seattle
> >
> >
>
>
> ________________________________________________________________
> The best thing to hit the internet in years - Juno SpeedBand!
> Surf the web up to FIVE TIMES FASTER!
> Only $14.95/ month - visit www.juno.com to sign up today!
>
--- End Message ---
--- Begin Message ---
Mine was vented with forced air during operation, but fan was off when
turning circuit breaker off and battery exploded.
On Tue, 10 Jun 2003 19:34:36 -0700 (PDT) Sheer Pullen
<[EMAIL PROTECTED]> writes:
>
> This makes it sound kind of like a hydrogen explosion - i.e. a tiny
> spark
> from a opening switch makes the battery go *boom*?
>
> Were both cars in question vented? Passive or active (with a fan)?
>
>
> On Tue, 10 Jun 2003 [EMAIL PROTECTED] wrote:
>
> > I had one (1) twelve volt Douglas Marine deep cycle 105 amphr
> battery
> > explode one night as I shut off the DC circuit breakers between
> the
> > battery pack and controller. It was one of 20 batteries in
> series for a
> > 240 volt DC battery pack to run a 230 volt DC 10 hp Westinghouse
> elevator
> > motor in my father's 1967 Ford Window Van. Douglas just said it
> was a
> > manufacturing defect, replaced the battery under warranty, and
> said I
> > would not be talking to them if it was not an isolated
> manufacturing
> > defect because otherwise all 20 would have blown up in my face.
> > Menlo Park III,
> > Bill
> >
> > On Tue, 10 Jun 2003 17:59:33 -0600 Michael Hoskinson
> <[EMAIL PROTECTED]>
> > writes:
> > > My friend Ken Norwick had some nasty experiences with YT's and
> if
> > > anybody can explain what he might have done wrong it would
> > > probably be educational for all. Ken is not a member of the
> > > list. About a year ago he switched to flooded 8 volt USB
> > > batteries and has had no trouble with them.
> > >
> > > His car is a 96 Saturn with a 9" ADC motor and Raptor 600 amp
> > > controller. He was using a Zivan NG3 charger. On 3 occasions
> he
> > > had an Optima explode in a cloud of acid mist and loud noise.
> > > These experiences had the undesirable side effect of reducing
> his
> > > wife's tolerance of the project and any future EV efforts. For
> > > some reason, she won't drive the car either.
> > >
> > > As Ken described it, on each occasion the pack had recently come
>
> > > off charge and he was within a block or two of starting out,
> > > drawing less than full amps (he was not specific about the amps,
>
> > > but I'd bet it was considerably less than, say Blue Meanie would
>
> > > pull on an average demo run). Then BANG!, cloud of acid steam
> > > and one of his batteries has no top. He told me that all of his
> > > connections were good and it was not a question of melted posts.
> > >
> > > Can anybody speculate on the cause of such a thing? I'm
> thinking
> > > perhaps overcharging built up pressure in the batteries and
> extra
> > > warming from current draw was enough to cause the explosion.
> But
> > > what do I know? If there are questions I should be asking Ken,
> > > please let me know.
> > >
> > > Mike Hoskinson
> > > ev-less in Seattle
> > >
> > >
> >
> >
> > ________________________________________________________________
> > The best thing to hit the internet in years - Juno SpeedBand!
> > Surf the web up to FIVE TIMES FASTER!
> > Only $14.95/ month - visit www.juno.com to sign up today!
> >
>
>
________________________________________________________________
The best thing to hit the internet in years - Juno SpeedBand!
Surf the web up to FIVE TIMES FASTER!
Only $14.95/ month - visit www.juno.com to sign up today!
--- End Message ---
--- Begin Message ---
Hmm. Ken's was not vented. Good thought.
I think I'll vent mine. :)
Mike
Sheer Pullen wrote:
This makes it sound kind of like a hydrogen explosion - i.e. a tiny spark
from a opening switch makes the battery go *boom*?
Were both cars in question vented? Passive or active (with a fan)?
--- End Message ---
--- Begin Message ---
Like the others I was thinking 10 amps but at 60 % ( about the eff of an
push pull amp) that would be about 600 watts of heat, not good . The two
people who have been asking me about this are musicians and want to power
there amps with there cars (both 120v). I said we could probable open the
amps up and find the + and - supply and have a speachel plug . No way !!!!
There not going to let this monkey take the back off a work p.a . so the dc
must be made to ac them back to dc,and it never happens .. So I've been
thinking about just building an power amp and using the EV pack with the
middle being 0 and a + and - 60 v , the perfect power amp, power supply and
no 60cycly hum.
----- Original Message -----
From: "Lee Hart" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Tuesday, June 10, 2003 4:00 PM
Subject: Re: DC to AC
> 1sclunn wrote:
> > I was thinking of something like a push-pull audio amp and play a
> > 60 or 50 cycle note into it. Yes, there would be some losses (60%
> > I believe) but a nice clean sine wave, would probably need 156v
> > to get the 170 peak peak then a step up transformer.
>
> That's a clever idea. It might even work! :-)
>
> Many years ago, when I first started experimenting with AC motor drives,
> I used a 4-channel stereo amplifier as my inverter. It was an easy way
> to produce 3-phase variable-voltage variable-frequency,
> variable-waveform outputs. The amplifier was rated at 40 watts per
> channel, which is about 18 volts into an 8-ohm load.
>
> The first thing I learned was that audio amplifiers do not like
> inductive loads. I got a lot of ringing and overshoot, which killed a
> couple sets of transistors. Adding diodes to the + and - supplies solved
> most of it. Changing capacitors and resistors in the amplifier's
> feedback loops to smooth out its frequency response also helped.
>
> I blew so many transistors that I relocated them to larger external
> heatsinks, and replaced the TO-220 transistors with higher power TO-3
> transistors in sockets.
>
> Efficiency is poor when it is running in standard linear mode (class AB
> as I recall). Efficiency improves if you overdrive it so it is working
> as in switching mode (on/off), but then you obviously get square waves
> out.
>
> Yes, you could use the low-voltage audio output to drive a transformer,
> to step the voltage up to any desired level.
>
> So, if you didn't want very much power (less than 100 watts) and didn't
> need the ultimate in efficiency, I think you could use an audio
> amplifier with a switchmode power supply (so it will work with a DC
> input) to generate 120vac.
> --
> Lee A. Hart Ring the bells that still can ring
> 814 8th Ave. N. Forget your perfect offering
> Sartell, MN 56377 USA There is a crack in everything
> leeahart_at_earthlink.net That's how the light gets in - Leonard Cohen
>
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--- Begin Message ---
I'll have to get it from the golf cart man and see what kind of batteries it
has. This may sound funny but for me I don't think I'd be as happy with it
as I am with my home built EV . All that computer stuff and no way to by
pass it or know what its trying to do . Look were its at now , broken and
probable something small and maybe it will have to be fixed by a ford
factory dealer (with 1800 dollar book) costing big bucks and lots of
towing. I'm sure fixed and working It's a nice EV and If the batteries are
NiMH even nicer , I'll try to get over there something this week ( lawn bis
is in full swing) .The starting bid on e bay will be 8k .;-) and I don't
think it will mater if I get it going or not to him.
EV god's have stopped throwing parts and are now throwing trucks at me , I
must be moving to slow.
Steve Clunn
----- Original Message -----
From: "Sam" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Tuesday, June 10, 2003 10:46 AM
Subject: Re: was over-priced EV on eBay/factory conversion.
> --- Sam Thurber <[EMAIL PROTECTED]> wrote:
> > Anything less than 10k would be a steal unless the
> > batteries themselves are bad. If it has NiMH
> > batteries, and they do take a charge, I would think up
> > to 20k depending on the condition of the truck itself.
> > If you don't buy it let me know :)
> >
> > -Sam
>
> --- 1sclunn <[EMAIL PROTECTED]> wrote:
>
> > He'd got the truck thinking that at worst he could put a gas engine
> > back if it didn't work , it was a 1999 . >
> >any Idea's on what it's worth?
> > Steve Clunn
>
> I would ask him where he got it. He may have picked it up from a county
> or city auction, CHEAP. Judging from the statement above, knowing the
> price he could have paid for an ICE 99' Ranger to begin with, it does
> not stand to reason he would spend very much $ thinking "oh well, if it
> doesn't't work I can always throw a gas engine in it".
>
> Sounds like the owner of the Ranger and whoever sold it to him didn't
> know what they really have/had. :)
>
> Of course I could be way off base, but that is how it looks from
> reading your post.
>
> Sam Ruble
>
> __________________________________
> Do you Yahoo!?
> Yahoo! Calendar - Free online calendar with sync to Outlook(TM).
> http://calendar.yahoo.com
>
--- End Message ---
--- Begin Message ---
--- 1sclunn <[EMAIL PROTECTED]> wrote:
> probable something small and maybe it will have to be fixed by a ford
> factory dealer (with 1800 dollar book) costing big bucks and lots of
> towing. I'm sure fixed and working It's a nice EV
> Steve Clunn
You might want to post a few questions on the ranger EV group.
http://autos.groups.yahoo.com/group/ranger-ev/
They most likely could get access to any manuals (for a very small
fraction of $1800) you would need and could answer a lot of questions
you may have about the truck, including troubleshooting.
Sam
__________________________________
Do you Yahoo!?
Yahoo! Calendar - Free online calendar with sync to Outlook(TM).
http://calendar.yahoo.com
--- End Message ---
--- Begin Message ---
Look's a little heavy for a hi proformer but would still make a nice EV.
have you been for a ride in a conversion?
----- Original Message -----
From: "Pestka, Dennis J" <[EMAIL PROTECTED]>
To: "'EV Discussion Group'" <[EMAIL PROTECTED]>
Sent: Tuesday, June 10, 2003 7:53 AM
Subject: !958 Chevy Truck Conversion
> Would like to do an old truck conversion.
> I'm looking at a 1958 - 1959 vintage Chevrolet.
> Would like reasonable performance instead of long range.
> Is this a good candidate for John Waylands high performance setup?
>
> Here are a few specs I have been able to get.
>
> Chevrolet Model 3104 Stepside Pickup
> 114" Wheelbase.
> 6.70-15 Tire Size.
> 3 speed manual transmission
> rear axle ratio of 3.90:1
>
> Weights:
> 3410# Curb Weight; 2015# Front 1395# Rear
> 5000# GVW
>
> 612# Engine and Clutch
> 65# Transmission
> 17.5 gal fuel tank
> 2" dia exh pipe.
>
> Other possible weight reduction could come with fiberglass body parts.
> They offer all parts for this vintage truck, but could become cost
> prohibitive.
> Just replacing the bed could shed ~ 300#, but at a cost of ~$2000.
>
> Is this vehicle a good choice, bad choice.
> I would like to do a pickup and have owned a few of these in the past.
> Thought it would be nice to do something different.
> I value any opinions or comments.
>
> Dennis
> Elsberry, MO
>
>
>
----------------------------------------------------------------------------
----
> * LP8.2: HTML/Attachments detected, removed from message *
>
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Maybe they are afraid of us converting their cars to electric. Lawrence
Rhodes.....
3.
TOYOTA STORY
Toyota is racing to make its cars at least as recyclable as those of
its European rivals, Volkswagen and DaimlerChrysler. The Japanese
automaker announced yesterday that the vehicles it produces in Japan
and Europe should be at least 85 percent recyclable by 2006 and 95
percent recyclable by 2016, up from 83 percent today. The move will
help Toyota expand its market share in Europe, where tough recycling
rules are on the books. It will also help the company reduce harmful
waste and cut costs by reusing parts from old vehicles. Toyota
reused 23,000 components from old cars in 2002 and intends to boost
that figure tenfold by 2010.
straight to the source: Detroit Free-Press, Bloomberg, Kae Inoue, 10 Jun
2003
<http://www.gristmagazine.com/forward.pl?forward_id=1220>
do good: Take action and pledge to buy an eco-friendly car
<http://www.gristmagazine.com/dogood/autos.asp?source=daily#pledge>
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I've posted a couple of pictures of my topless batteries.
www.members.aol.com/steveb48/pack.jpg shows the overall mess
www.members.aol.com/steveb48/pack2.jpg has the watering system and balancer cables
removed. The highlighted area is the source.
www.members.aol.com/steveb48/hole.jpg is an out of focus closeup of the hole the arc
burned through the battery top.
I checked the charger schematics and verified with a meter. The chassis is tied to AC
Neutral in the charger. Joe, this is what you pointed out to me months ago. Looks like
I've got a bit more work to do.
I hooked up 2 of the topless batteries in place of the DC/DC convertor and turned on
the lights to kill the batteries. Why do they take so long to go dead when you want
them to and go dead so quickly when you don't?
Steve
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Sounds good to me, where could I get 4-5 of these for $4.00 each tho?
James
I'm so glad you asked. It's my favorite. Excess Solutions in San Jose
California. I 'm sure there is an electrionics outlet in your area though
that might have some. Ask around. Maybe someone on the list will volunteer
some leads & advice on how to wire them. I have one on my headlight and one
for the running lights. You might need one for each headlight. One for the
fan. Wipers not sure. You might need 4 or 5 small ones. Lawrence
Rhodes......
> Quoting Lawrence Rhodes <[EMAIL PROTECTED]>:
>
> > A little trick might be to use two 36v small 35 to 50 watt dc/dc units.
> > Getting power each from half the pack. This will charge your battery.
> > Run
> > your lights. 4 bucks a piece. Lawrence Rhodes...If they weren't enough
> > you
> > could use more.........
> >
> >
>
>
> Sounds good to me, where could I get 4-5 of these for $4.00 each tho?
>
> James
>
--- End Message ---
--- Begin Message ---
OK don't forget these are 35 to 50 watt converters. You will need a bunch.
I also use a 35 watt headlight bulb to make sure it works. Lawrence
Rhodes......
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----- Original Message -----
From: "Lee Hart" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Tuesday, June 10, 2003 11:47 AM
Subject: Re: 72V dc/dc
> [EMAIL PROTECTED] wrote:
> > Sounds good to me, where could I get 4-5 of these for $4.00 each?
>
> This would be an astoundingly low price; pennies on the dollar. Either
> the seller doesn't know the value of what he's selling, or he knows full
> well and hopes the *buyer* doesn't! (i.e. it is junk, scrap, out of
> spec, etc.)
>
> There are several ways to look at this whole "surplus" situation.
>
> First, there's the conservative "do it right the first time" approach.
> Buy the best part for the job, even if it costs more. Buy based on
> quality, performance, and correct fit:
>
> - I spent serious money on my car, and don't want to wreck it
> using substandard parts.
> - I want it to be reliable, and last a long time.
> - I want something that "just plain works".
> - I don't have the time or experience to modify something that's
> "close" so it will fit or work.
> - I don't know which specs are important, and which ones I can
> skimp on without affecting the end result.
>
> Then, there's the hobbyist's approach. I'm doing this for fun, and to
> learn. Money is the most important factor; everything else can suffer if
> the price is right.
>
> - I'm trying to do this as cheap as possible.
> - Reliability is not important; if I fixed it once, I can fix
> it again.
> - I enjoy tinkering and modifying things to see if I can get
> it to work better.
> - I have plenty of time; no deadlines to worry about.
> - I am a skilled technician or engineer, and know how it works,
> and understand the tradeoffs and their consequences.
>
> I use surplus parts a lot. You can find great deals if you know what
> you're doing. EVs are a hobby for me, and I can't justify spending large
> amounts of money on it. But, I also know a lot about the parts I'm
> buying, how to use them, and their limitations. I also enjoy
> experimenting and tinkering, to explore the limits of what works (and
> what doesn't). And I still get stung sometimes; a part that looks great
> turns out to be useless and a complete waste of money (even at 1 cent on
> the dollar).
>
> But I would not recommend using surplus for inexperienced or first-time
> EVers, unless their financial situation is so bad that they have no
> choice. If you don't know what you're doing, you can wind up buying
> parts that are defective, or just plain won't work in your application.
> Or, you get something that doesn't work right or has safety problems,
> which you don't recognize due to inexperience.
>
> In the case of the Henney, the original solution was a large enough 12v
> accessory battery to cover the accessory loads, and an off-board 12v
> charger to recharge it at the same time as the propulsion pack. It will
> be easy to buy a good 12v battery and quality charger, so this solution
> will work right away, and keep working for many years.
> --
> Lee A. Hart Ring the bells that still can ring
> 814 8th Ave. N. Forget your perfect offering
> Sartell, MN 56377 USA There is a crack in everything
> leeahart_at_earthlink.net That's how the light gets in - Leonard Cohen
>
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Isn't it all AC after commutation?
Correct me if I am wrong, i have been trying to naildown motor
characteristics for a while.
Do we mean induction vs Commutation ?
The series motor has the guts off the line because of low rotor voltage,
very low back emf.
either magnet or rotor windings create back emf as rpm increases
subtracting from avail torque. The comutator gives you a freq range down
to 0hz.
Induction motor has currents induced in bars due to slip, So much at
start that heat is a major problem. what is the minimum frequency of an
automotive sinewave(AC) drive?
Sep-exite helps extend useful Series -DC operating range
Varible freq helps reduce heat on induction motor.
Why not use an AC drive on a wound rotor motor with slip-rings to a
solid state "resistance" that regens excess rotor energy back onto the
line and can inject voltage into the rotor to lock it into sync for
cruising. Slip rings are continous contact so there is very little
arcing,dust,loss. ( seems ideal motor fro EV to me.)
Is there a difference in construction between a PM AC syncronous motor
and a Brushless DC motor?
Another newbie question, this one about batteries :
what causes all the problem when charging a series string of
batteries? how does buddy pairs help? would the following, auto equalize ?
-----------------------------------36V
|
------------------------------
[ 50ah ] [ 50 ah ]
--------|--------- ---------|---------
[25ah] [25ah] [25ah] [25ah]
-----|---- ------|---- ------|----- -------|------
[12] [12] [12] [12][12] [12] [12] [12]
-------------------------------------------------------------0V
Jeff Shanab
EV hopefull.
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Lee Hart wrote:
>> The first thing I learned was that audio amplifiers do not like
>> inductive loads.
Sheer Pullen wrote:
> U'm, Lee, by definition audio amplifiers DO like inductive loads
> - what do you think a speaker is ;0-)
Millihenries, yes. Audio amps see this much inductance from speakers and
crossover networks. Henries, no. That's a thousand times more
inductance. Plus, motors are able to act as generators, and DELIVER
substantial amounts of power back into the amplifier's output.
> seems kind of the painful way round - if you're driving a power
> supply anyway, why not just use one of the $30 inverters?
If the audio amp has a switchmode power supply, it may well accept a
"universal" input voltage; anything from 90-264vac or 100-400vdc. It's
hard to buy an inverter with this wide an input voltage range.
The audio amp can deliver a true sinewave output (albeit at lower
efficiency). With an output transformer (or autotransformer or variac),
you can adjust the output voltage to anything needed.
So, it is pretty versatile.
> Audio amps would seem to be a neat way to prototype the power stage
> of a inverter, though.
Yes, it was good for that. I learned a lot about what kind of
optimizations were actually useful for AC motor drivers. How much better
*does* a motor perform with real sinewaves as opposed to square waves or
various pseudo-sinewaves?
The simple answer is that perfect sinewaves aren't needed, and that even
crude 6-step waveforms give you 90% or more of a motor's sinewave
performance and efficiency.
--
Lee A. Hart Ring the bells that still can ring
814 8th Ave. N. Forget your perfect offering
Sartell, MN 56377 USA There is a crack in everything
leeahart_at_earthlink.net That's how the light gets in - Leonard Cohen
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Ryan Fulcher wrote:
> OH! HAY!! How about using the heat sink as the actual
> connection between cells? See picture below.
It should work. The big question is how much heat you can actually
extract this way. I might try a discharge cycle with the cell upside
down in a pan of water; the water will act as an "infinite" heatsink and
hold the terminals at ambient temperature no matter how hot the cell
gets. So, I could see how much (if any) cooler the plastic walls of the
cell run.
An aluminum heatsink might be a challenge, as it is difficult to make a
good electrical connection to aluminum.
--
Lee A. Hart Ring the bells that still can ring
814 8th Ave. N. Forget your perfect offering
Sartell, MN 56377 USA There is a crack in everything
leeahart_at_earthlink.net That's how the light gets in - Leonard Cohen
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Seth wrote:
> I think it has something to do with needing three 2000amp half
> bridges instead of one, for starters.
Exactly so.
A series motor tends to multiply torque. In theory, Torque =
FieldCurrent x ArmatureCurrent. Since the field and armature are in
series, this becomes Torque = Current^2. The torque per amp at high
currents is fantastic.
In practice, magnetic saturation limits the actual torque to something
less than current^2. The exponents is somewhat smaller than 2. However,
as long as it is more than current^1, the series motor beats just about
any other type at supplying high torque.
An AC induction motor has Torque = Current^1. You only get high torque
with high current. Now, the inverter is stepping the voltage down, and
so stepping the current up. But the transistors and diodes in the
inverter still have to be sized to carry the peak current. To get 1000
motor amps, you need 1000-amp semiconductors.
Thus, the AC inverter is going to need something like 6 times the
silicon to match an equivalent series motor. Possible; but expensive!
> people like me can do modest, crude power (200A) for a buck converter
> for a series or PM brush motor. But asynchronous AC... I hear about
> space vector, third harmonic, eigen this or that and the other.
All this is just to optimize efficiency -- not raw horsepower or torque.
If you want maximum starting torque, it's easy. Hit the motor with its
slip frequency at full pack voltage, and get out of the way! That motor
is going to start turning -- or break something!
> now I know Rich is allergic to white lab coats ;-)
Not from lab technicians; from the doctors at that hospital that applied
all those 2x4 "treatments" (Drs. Dube, Wayland, Wilde, et. al. (I'm only
kidding, folks :-)
> maximum stall torque per transistor to make the "electronic
> transmission" a reality is a very important goal, from a
> marketability point and saving costs on the controller. "We
> haven't figured out the motor math yet, so we just use 800 amp
> modules for 35kW at 336VDC and hey, 750 watt-hours per mile
> isn't bad for a compact car" isn't going to cut it at review
> time for *that* motor engineer.
Very true. The inverter and AC motor for an on-the-road EV has to be
very efficient; it is competing against the much cheaper DC series motor
and PWM controller, which are 80% efficient or better. If your AC drive
can't beat it, you don't have a product!
But for drag racing, efficiency per se is not all that important. You're
only going to be racing for a matter of seconds. The series DC motor and
PWM controller is only 50% efficient under these conditions. So your AC
drive doesn't have to be 90% efficient; even 60% will do.
But, nobody is designing an AC drive for these conditions. They could!
-- they just aren't. There are enough examples of very high power AC
drives to show that they are possible. TV antenna rotators use tiny
2-phase AC motors to move monsterous antennas. There are 400 Hz AC
aircraft motors for moving flaps and landing gear; applications that
demand very high power for very short lengths of time. Torpedo motors
are another example.
I honestly think the way to build an AC motor with extremely high peak
power is with a hybrid inverter. Half transistors, half mechanical
switches (commutator). The mechanical switches do the work at full
throttle. The transistors take over at anything less, when more finesse
is called for.
--
Lee A. Hart Ring the bells that still can ring
814 8th Ave. N. Forget your perfect offering
Sartell, MN 56377 USA There is a crack in everything
leeahart_at_earthlink.net That's how the light gets in - Leonard Cohen
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>
> An aluminum heatsink might be a challenge, as it is difficult to make
a
> good electrical connection to aluminum.
> --
Why would you have to make an electrical connection to the aluminum?
All you need to transfer to the aluminum is the heat. Why not just use
a copper buss bar between the batteries and clamp the aluminum heatsink
somehow to the buss bar? Or am I missing something here?
-Bryan Avery
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Hi Lawrence,
Do these guys have a web site for those of us who are out of the area, or in
my case out of the country ?
I have just got my 72 volt car going today and I could probably do with a
few of these.
thanx
Garry Stanley
Cable.net.nz
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Hi Folks,
Some of you will remember a few months back I thought I would get my EV
conversion done in a couple of days and no one thought it was likely and as
it turns out they were right.
The original plan was to use the motor from the 48 volt tower and put it in
a Suzuki van, but this got put on hold because the toer has some value as it
stands and a lack of space meant that there wasn't really room to spread
things out and play.
Because of the toer value I looked around and a few days later located a non
working forklift complete minus batteries and went and paid $600 for it,
along with its charger.
Off down to my used battery supplier and got a dozen 6 volt sealed deep
cycles the same as the 8 I had for the toer for $10 each.
A building refurbishment delayed starting again but I did manage to spend a
couple of Sunday afternoons pulling the forklift apart and I was pleased to
find that not only did it have 2 decent sized motors but it had 2 completely
separate controllers.
The second controller is much smaller than the primary one and is only a
soft start controller, so I have decided to use the second motor on a
motorbike frame I have been experimenting with
The Suzuki posed another problem in that its diff ratio is 6 to 1 and the
motor only runs to 1750 rpm meaning without counter gearing it would only do
25 kph and I wasn't keen to gear up and lose power to the added friction
etc.
I was given a 1986 Mitsubishi station wagon without a motor that had also
become a casualty of the building renovations and the lack of space this was
causing.
Last weekend I spent Saturday and Sunday making the adapter and mounts to
connect the motor to the gearbox.
Monday night I put in a few hours connected all the wires mounted the
controller and stuck all the batteries in the back and wired them together
Tuesday night I got a couple of decent cables to go from the front to the
back and connected everything up, but no go.
Today I stopped in at the forklift place brought a connector and was told th
at the guy I needed to talk to was actually out where my workshop is and if
I was lucky and he had a few spare minutes he would call in and have a look.
I rang him when I got to work and about an hour later he showed up, he spent
about half an hour during which I got a good understanding of my motor and
controller and how it all works but other than seeing that it didn't have
voltage where it should have had and had some where it shouldn't have had,
he wasn't able to get it to go.
About half an hour after he left he rang back and said that there was a hand
brake switch that I didn't have and that this stopped the motor from
starting while the hand brake was on and that if I applied power to the
switch that should have had power it would probably go.
Off out to the workshop I went and connected power and hey presto a new EV
was born.
I have temporarily connected the car throttle pedal to the controller pot so
a test drive can be done.
I still have a few hours work to do on this, the batteries in the back might
work, but they sure weigh down the back and the front is already up because
the motor doesn't match the engine weight but it will do for a few test runs
around the block as soon as the weather gets better.
I will no doubt have a gazillion questions over the next few weeks, but the
one I would like feedback on right now is, the tech pointed out that this
forklift was designed to use the motor in reverse for braking and while
overdriving the motor forward will recharge the batteries, will this too
recharge the batteries if it is running in reverse ?
Garry Stanley
Cable.net.nz
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I have not read much about people doing conversions without transmissions.
I can see the all the advantages.
What are the drawbacks and limitations to doing this?
Dennis
Elsberry, MO
-----Original Message-----
From: Eric Penne [mailto:[EMAIL PROTECTED]
Sent: Tuesday, June 10, 2003 10:20 AM
To: [EMAIL PROTECTED]
Subject: Re: 1958 Chevy Truck Conversion
Consider
shortening the drive shaft and not using a tranny (clears up the floor
board) and putting the motor(s) behind the cab or behind the rear axle and
filling the rest of the space with batteries.
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Trace Engineering makes reliable inverters, not sure about 50 hertz though.
Check their websight traceengineering.com Also I was thinking of doing this
for a well pump 240vac/60 hertz at 6A and was thinking of using the peak
voltage 336V at 70.7% duty cycle to simulate the area of a sine but be able
to direct drive with a flash MC68HC908QY4 by Mot and IR2111 high side fet
drivers by IR. Still a fair amount of work.
----- Original Message -----
From: "Peter VanDerWal" <[EMAIL PROTECTED]>
To: "EV" <[EMAIL PROTECTED]>
Sent: Tuesday, June 10, 2003 9:16 PM
Subject: Re: DC to AC
> Wouldn't this be fairly easy to build? Assuming you can get by with a
> modified sinewave (aka modified square wave) inverter. All you'd need
> is an H-bridge and a transformer to step up the voltage. Well, that
> and something to drive the H-bridge, but that should be fairly simple.
>
> On Tue, 2003-06-10 at 04:32, Mark Fowler wrote:
> > Hi all,
> >
> > I'm looking for an inverter that takes my DC pack voltage (144V DC) and
turns it into 240V 50Hz AC (Australian mains current).
> > The closest I've been able to find is combining a DC/DC (144V -> 12V)
with a 12V to 240V inverter.
> > I want to avoid massive 12V currents (and massive DC/DC) to get a decent
amount of power from the inverter.
> >
> > Does such a beast exist?
> > What sort of price?
> >
> > Mark
> >
> --
> EVDL
>
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On Tue, 2003-06-10 at 22:55, Jeff Shanab wrote:
> Isn't it all AC after commutation?
>
> Correct me if I am wrong, i have been trying to naildown motor
> characteristics for a while.
>
> Do we mean induction vs Commutation ?
>
> The series motor has the guts off the line because of low rotor voltage,
> very low back emf.
Umm, no. Well at least not directly. Off the line the series motor
might have very high rotor voltage.
What gives it it's high torque is that the huge current going through
the rotor is ALSO going trough the field and producing TWO large
magnetic fields (field and armature). Theoretically doubling the
current in a series motor results in four times the torque, reality is
generally less than that due to saturation, etc.
> either magnet or rotor windings create back emf as rpm increases
> subtracting from avail torque. The comutator gives you a freq range down
> to 0hz.
back emf does not subtract from torque unless it causes the current to
drop. Most racing controllers are current limited until very close to
the end anyway.
>
> Induction motor has currents induced in bars due to slip, So much at
> start that heat is a major problem. what is the minimum frequency of an
> automotive sinewave(AC) drive?
Heat is a major problem in ANY motor with huge currents flowing.
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