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Old 03-29-2009, 02:22 AM   #1 (permalink)
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Battery arrangement questions???

So I'm curious...
Coming from 6 years of electric RC car racing, I always noticed that a battery pack with fewer cells seemed to be more snappy and accelerate quicker, but obviously didn't have the top speed. More cells were just the opposite effect, I figure because there is the extra internal resistance of the added cells?
I'm too far from work to ever look at an electric car unless they start getting some serious range AND affordability, but I'm curious, has anyone ever played with or is there a system availaible where the batteries would be wired in several "banks" that would get switched from parallel to series to better meet amp load and voltage requirements?
Seems like something like this could provide some serious amps and alot more acceleration, while at the same time would be easier on the batteries....

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Old 03-29-2009, 09:54 AM   #2 (permalink)
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My electric car has 2 24 volt banks of batteries and uses them both at the same time switching between 24 v for low speed and 48 volts for high speed.
I assume that your question tho is regarding packs that look like 4 "C" cells comparing them to packs that look like 8 "AA" cells? the larger lower voltage pack is going to have more amps that can be drawn out of it but a limit your top speed like you say.
The key is a battery that can handle a high discharge rate.
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Old 03-29-2009, 03:59 PM   #3 (permalink)
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A "switched" battery pack could work well for something like drag racing.

For typical driving, it's not really ideal. Just go with higher voltage for better top speed. With the increased voltage, you also need fewer amps for the same work, so your batteries will tend to live longer.

Let the PWM controller do all the hard work for you.

My "Turbo-circuit" was basically a switched battery pack. It worked frighteningly well, but I will be much happier with a higher voltage controller!
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Old 03-29-2009, 11:19 PM   #4 (permalink)
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Quote:
Originally Posted by bennelson View Post
A "switched" battery pack could work well for something like drag racing.

For typical driving, it's not really ideal. Just go with higher voltage for better top speed. With the increased voltage, you also need fewer amps for the same work, so your batteries will tend to live longer.

Let the PWM controller do all the hard work for you.

My "Turbo-circuit" was basically a switched battery pack. It worked frighteningly well, but I will be much happier with a higher voltage controller!
I'm intrigued by electric, but if I end up going that route I want something that has some kahuna's and gets a move on when you want to go. Your battery turbo idea is a pretty cool one, but as already said I'd worry about the life of the batteries with them not seeing the same usage. Ideally when you purchased the batteries if you had a whole bunch and could get them "matched" by peak voltage and capacity the group would perform much better and last longer.
Awhile ago is was looking into a EV conversion kit, I think it was kit #4 from wilderness EV or something.
I found so much contradicting information from some people saying it would work great to others saying they were dead batteries after 10 miles that I decided against it(20 miles of 50-60mph plus alot of stop and go once in town-each way to work).
All the new EV technology also quickly gets buried or priced out of reach of the average joe which is also very frustrating...
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Old 03-30-2009, 03:09 PM   #5 (permalink)
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Who needs "New EV Technology'!?

Lead acid batteries are over 100 years old, and contactor controllers are as simple as can be.

My electric car project has cost about $1300, including buying the car in the first place.

My Citicar (currently under restoration) was purchased for $800, including a 72V 450 amp PWM controller and battery charger.

If you want fast, check out:
World’s Top 10 Fastest Electric Cars : Gas 2.0

Or do a web search for Killacycle or White Zombie.

Lots of people just have odd expections on what a car has to be, mostly because of our culture, and it's powerful advertising media.

Hop in an electric vehicle. You will be glad you did!

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