I bought some li-ion cells for a dollar a piece and was hoping to use a couple in series to give 7.4v. However they do not want to co-operate. When I connect them in series the voltage just dies to millivolts?
Individually they work fine putting out 3.7v and although I haven't discharged one fully yet I suspect they'll run close to the 670mAh they are rated at.
IS there something specific to li-ion batteries that you can't just hook them up in series like other cells? This one has me puzzled. If I can't work it out I'll just have to do a booster I guess.
charging Sounds weird… I recomend to charge both full and recheck all wires and connections and polarities after connecting. First thing i can think of is that one of the batteries is connected the wrong way.
Just an update to this situation I have with these batteries. I have since obtained some pololu gear motors which run fine with these batteries. The original problem I had was with running the tamiya twin gearbox/motors which I believe draw about 600mA each.I realise now how stupid I am in not having mentioned this. Sorry for those who tried to help. Even individually I cannot run one of these motors from the battery. I guess the limit to the amount of current they can supply is less than 600 mA except I don’t have any spec sheet to tell me how much that is. I would have thought they would have handled the tamiya motors but they don’t. At least I can use them now with the pololu chassis I bought.
I guess an experiment gradually increasing current draw until it stops might be one way to find out. Or is there a general rule for Li-ion batteries based on their capacity as to their maximum current draw.