Quote:
Originally Posted by Cobb
I want to give that a try, but the kits I see on ebay are hundreds of dollars.
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This 350F kit on Ebay is $65 and would probably do well to replace a battery on a motorcycle that doesn't have a computer (carbureted most likely).
I built my own kit with 400F capacitors and replaced the battery on my bike, but since it has a computer (fuel injected), it draws the voltage down to a level that will not start in about 4 days (8v approx). I've got a battery tender on it to maintain the voltage, but it doesn't really matter since I have a steep driveway and can always bump start if my capacitors are low.
This 1500F kit is $209, and would probably give my bike a couple weeks of sitting time. Not sure if it would fit in the battery compartment though, since my 400F is snug with the Styrofoam enclosure I made for it.
I wonder if a LiFePo4 battery could be connected in parallel to a supercapacitor with a resistor (70 ohms) to limit the current flow between the battery and the capacitors? The idea would be that only the capacitors would be used to start and run the vehicle, but have the battery provide a very small topping charge when the car sits. Charging at sub-freezing temperatures is OK as long as the current is held sufficiently low. From what I've heard, discharge at low temps is ok.