So the next obvious question is "How am I going to charge these things?" LiFePO4 batteries can be charged in as little as 5 minutes if your charger can handle it. I want my charger to work when I plug it into a standard 120 volt US wall socket, which limits me to 15 amps. 15*120=1800 Watts maximum. My battery pack is 1561 Watt-Hours (8cells per pack*21 packs*3.5 volts per cell*2.665AH per cell). This means I can charge my batteries in 52 minutes (1561/1800*60minutes) if I can find a charger that can handle the current. Fortunately, I have two 100 volt 10 Amp motor controllers that should do the trick (see photo). Since I'll charge each cell to 3.65 volts, I need to limit my charge voltage to 87.6 volts.FYI: The charge process for LiFePO4 is constant current until the cell reaches 3.65 volts. Then you hold constant voltage until the current drops to C/10 (rated capacity, i.e. I'm using 2.655AH cells, so we hold constant 3.65 volts until the cell takes .2655 amps).
