A123 lliFe parallel/series conundrum

[Jolfstn74]

Good evening from Eastern greeter Seattle area, in the photo I supply I have 3 20 volt six s4p life cells I have them in this configuration for ease of charging on my hobby charger, but I want to put them together in series for 60 volts on my e-bike and when I put two together I get 40 volts and when I put three together I get 20 volts can anyone tell me why this is happening?

 

[Jolfstn74]

I did check the polarity of the positive and negative and determined I was not accidentally putting one in parallel instead of series which would make sense but that's not what's happening

 

[Jolfstn74]

Perhaps it's a bit narcissistic to answer my own query but one of those three battery packs the polarity was reversed now I have 60 volts I know I said I check all of them and they were right I thought I did but I'm very dangerous because I only know a little bit about stuff just enough to be really hazardous

 

[john61ct]

Yes you may well have "shortened the lifespan of" (aka damaged) one or more of the packs playing around without testing first with a DMM

Lucky you did not cause a "rapidly expanding fire" (aka an explosion)

Yes LFP is saf**er** than the other higher-voltage chemistries

does not mean they are **safe** in the hands of noobish / careless users

 

[Jolfstn74]

I learned the hard way, was building 4p 6s & had soldered the balance wires but hadn't yet attached the plug, pack got knocked over & within seconds four cells Burst into fire. Luckily it was only limited to those 4 cells.

 

[999zip999]

How many amps are you going to be using this 60 volt pack at ? You could use xt90 antispark one way safety connectors. Still have check polarity when installing.