[EVDL List]

>
> Message: 7
> Date: Sun, 20 Feb 2011 01:17:48 -0800 (PST)
> From: Jeff Major <[email protected]>
> Subject: Re: [EVDL] capacitor balancing
> To: Electric Vehicle Discussion List <[email protected]>
> Message-ID: <[email protected]>
> Content-Type: text/plain; charset=iso-8859-1
>
> Hi Jack,
>
> You are making this way too difficult and complex. All you have to do is
> look at the total series string voltage to know when to cutback regen.
> These caps stay in balance very well. They can be completely discharged to
> zero volts to get them all in line to start off. Maxwell had a little
> circuit card which went between every other cell which I used on that set-up
> you saw on the DIY. It was an N-1 arrangement which bled down a cap if it
> went too high at like a couple hundred milliamps.
>
> We did 1000's of regens at up to 400A peaks and never had a cap problem
>
> Jeff M (major)


this is my plan, just use the maxwell boards. I found them at a decent
price. To protect the caps after paying for them, Id like to keep them
around for as long as possible! So ill pay a little bit "insurance"

http://www.rell.com/Pages/Product-Details.aspx?productId=842993
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[EVDL List]

From: Jeff Major
> Hi Jack,
>
> You are making this way too difficult and complex. All you have to do is
> look at the total series string voltage to know when to cutback regen.
> These caps stay in balance very well. They can be completely discharged to
> zero volts to get them all in line to start off. Maxwell had a little
> circuit card which went between every other cell which I used on that set-up
> you saw on the DIY. It was an N-1 arrangement which bled down a cap if it
> went too high at like a couple hundred milliamps.
>
> We did 1000's of regens at up to 400A peaks and never had a cap problem

I agree; capacitors are easier to balance than batteries. Running dead
won't hurt them (though reversing them will). If overcharged, the
voltage doesn't suddenly rise like batteries do; instead, it just keeps
ramping up at the same rate it does at lower states of charge. This
gives you time to back off the current. They also aren't hurt by high
charging currents when already close to full.

But, I'd still want to keep an eye on them, especially at high currents.
Things can happen very fast at high currents! If you don't know which
one has the lowest capacity, you won't know which one will go dead and
reverse, or go overvoltage on charge first.
--
Lee A. Hart | Ring the bells that still can ring
814 8th Ave N | Forget the perfect offering
Sartell MN 56377 | There is a crack in everything
leeahart earthlink.net | That's how the light gets in -- Leonard Cohen

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