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zeropointbug · 06.22.2009, 02:22 AM

Linc, I have been tempted to make a A123 car starter battery as well.

Well, I charge my A123 packs with 3.8v/cell @ 10amps/2.3Ah... for a 4s pack, that's 15.2 volts, that's roughly what lead acid chargers peak at. You should take some measurements on the road of what the leadacid batt is idling at, if it's between 13.8volts and 14.4volts, you should be good, as that is the recommended charging specs for them. I'm sure they can handle being 'held' at 3.6v/cell for as long as you ride the bike, and anything lower, is better. A 4s4p pack should work just great. That's a 3000watt/4hp pack.

13.8volts is 3.45v/cell, which is the recommended float-charge voltage.

14.4volts is 3.6v/cell, that is the standard charge voltage.

So I think if you are in between that range for stator voltages, you should be golden. Even if 3.45v/cell doesn't charge it to 100% SOC, the pack should have more than enough energy and power to start the bike.

If you build the pack right, that should be the last batt you buy for your bike. no doubt.

	(#2)
zeropointbug Z-Pinch racer Offline Posts: 3,141 Join Date: Nov 2006 Location: SK, Canada	06.22.2009, 02:22 AM Linc, I have been tempted to make a A123 car starter battery as well. Well, I charge my A123 packs with 3.8v/cell @ 10amps/2.3Ah... for a 4s pack, that's 15.2 volts, that's roughly what lead acid chargers peak at. You should take some measurements on the road of what the leadacid batt is idling at, if it's between 13.8volts and 14.4volts, you should be good, as that is the recommended charging specs for them. I'm sure they can handle being 'held' at 3.6v/cell for as long as you ride the bike, and anything lower, is better. A 4s4p pack should work just great. That's a 3000watt/4hp pack. 13.8volts is 3.45v/cell, which is the recommended float-charge voltage. 14.4volts is 3.6v/cell, that is the standard charge voltage. So I think if you are in between that range for stator voltages, you should be golden. Even if 3.45v/cell doesn't charge it to 100% SOC, the pack should have more than enough energy and power to start the bike. If you build the pack right, that should be the last batt you buy for your bike. no doubt. “The modern astrophysical concept that ascribes the sun’s energy to thermonuclear reactions deep in the solar interior is contradicted by nearly every observable aspect of the sun.” —Ralph E. Juergens