Quote:
Originally Posted by teoman
A lead acid sits at 13 ish volts. So you are essentially wasting delta 3V.
In my un investigated case, the capacitors are not sufficient to start the vehicle (i probably need to do a better connection to the capacitors). I am thinking of a small boost converter to top the caps to 16V for startup.
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The capacitor's lifespan at maximum voltage is shorter. You lose some energy capacity but does that really matter for something that weighs under 1lb?
Leakage current means it's not optimal for long term storage anyhow. Mazda i-ELOOP uses a 24V cap bank and 24V alternator with a DC-DC converter to drop it down to 12V. There is a 12V battery to provide standby power as well. The purpose of the 24V is more about increasing alternator power and efficiency, and the capacitor is 25kJ (so most likely 80 farads, 10 800F caps in series ish).
If you're not using a mild hybrid system, you have no need for high power energy storage. You only need one second of high-power discharge to crank the engine, which a supplementary cap will provide very nicely when paired with any cheap battery (that provides reserve capacity).