[redpoint5]

I've read through all of Maxwell's literature on the supercaps, and among the things I read is that leakage occurs at a faster rate as the voltage increases.

This means that capacitors will self balance as long as they aren't continuously held on a charge. Whenever the vehicle is turned off, the capacitors will slowly bleed off voltage due to leakage, and it will do so at a more rapid rate for the highest voltage caps.

I don't believe it's necessary to have a balance circuit for vehicle applications as long as the total voltage doesn't get too close to the maximum allowable bank voltage of the capacitors.

For a 14.4v alternator output charging 6x 2.7v capacitors, that amounts to only 2.4v per cell, leaving 0.3v headroom for some capacitors to be a little higher than others. This seems acceptable to me.

Originally Posted by ECONORAM

To make sure I'm thinking right, I could use 12 super caps at 350F each, in a series parallel setup with balance circuits as a battery assist, yes? I've been watching this: Ultracapacitor Module Kit Battery Eliminator Car Audio Starting Remote Solar | eBay
The 2000F capacitors look good, but I don't want to spend $300 on a capacitor set...

Yes, it works, but I wouldn't do it that way. It's not space or cost effective. Buying higher farad capacitors is cheaper than trying to parallel the capacitance you want, and they will take up less space and likely last longer since there are fewer points of failure.

The same seller has 6x 1500 farad caps for $180, which is just a little more than buying 2 of his 350 farad kits. As Enki points out, the 1500s would give you more than twice the capacity.