hanks, Bob. If mine act even close to that, the relay sounds like a perfect boost-pack LVC solution. Seven a123's in series would cut-out at about 2 volts -- hopefully high enough that, even under a brief 60-amp draw, none would be courting reversal should the pack be somewhat imbalanced; but not so high I'd lose useful boost-pack capacity. Does this sound right to you?
7 cells will drop out at 20v i think you mean? i am assuming you want to set the relay latch for boost and have it drop out if the a123 string hits low voltage... i would say 21v but if you draw 60A that would be about 20 and would not drop out the relay, but if a cell drops to 0v that would make it 17v and you would like it to drop out there. it might, and you could put diodes or resistance in the coil to tweak it, but i would rather it drop out reliably at 19v when one cell hits 2v or so, and the simplest way to do that is probably to use a zener to turn on a transistor until the voltage drops, it's simple and will be more reliable than relying on the dropout voltage of the relay. if you use a zener voltage of 18v (you could use 3 ea. 6v znrs)and a switching silicon transistor or fet and bias the zener on so it keeps the transistor on until the voltage drops that transistor could hold the relay coil latched. `
