[serialk11r]

If you use caps, go small and pair with a battery, unless you're plugging your car in everyday. Caps self-discharge much faster than batteries do, so you really want to just use the minimum amount to boost the starting capability if you absolutely have to.

Honestly, LTO has made the typical activated charcoal EDLC pretty obsolete. LTOs have absurdly high power density and cycle endurance. If you want to save a few bucks, you can get vanilla LiFePO4 and pair it with supercaps, but that combo will self-discharge faster and the battery can't go below freezing.

Maybe someday we'll have carbon nanotube EDLCs that can completely replace starter batteries, but for now a battery is still good to have.