Hi everyone. I'm a long time lurker but I've made something that you guys might find value in, so I signed up and created this thread. I made an ultracapacitor replacement for the 200 year old tech heavy blocks of lead (a.k.a. the batteries) that can be found roughly in the front of our cars.
This ultracapacitor array weighs roughly 8 lbs, which is DRAMATICALLY lighter than just about any possible alternative out there. This is good for those of us putting our cars on a diet.
It's tolerant of deep discharge and can be cycled hundreds of thousands of times - as opposed to lead acid which can be cycled a few times at most. This is very handy for winter storage, which is important where I live. It also charges extremely quickly, less than a minute usually, but this is completely dependent on what you're charging it with. I would not recommend a normal transformer based battery charger as the poor voltage regulation may outrun the balancing circuits.
Unfortunately the capacity (amp-hours, or "reserve capacity") is much less than a normal lead acid battery. If your alternator fails you'll only have a few minutes to get to safety before your engine dies. Additionally, I can only leave the car undriven for about 3 days before the voltage really starts to sag. I've taken care of this with the addition of tiny little ultra light weight solar cells behind the rear seats under the rear window. It looks very clean and is unobtrusive.
This was a very easy build and much more cost effective elimination of weight than things such as a composite hood. I just spent a few thousand to save 25 lbs on a hood, while this ultracapacitor cost about $300 and eliminated much more weight than the hood did.
I hope someone finds this useful. I have many more pictures, details, and brackets which are 3D printable to mate up to the stock battery hold-downs which I can post if anyone is interested in this project.
Ultracapacitor array close-up.
Battery cover removed.