16s 280Ah cell pack messed up? (SOLVED)

[RoamingTuRDle]

Another one for those to learn from maybe...

With my DALY (Deligreencs) everything was running ok but the battery pack seemed to be unstable and did not seem to balance that well. The BMS would kick off well before the pack was empty.

I decided to get an active balancer of Amazon and while hooking it up I dropped the wrench too low (very tight space) and did not have the wrench insulated well enough. Short story long I shorted across cell #2 +/- for a second but I got the wrench up pretty quick (burnt the heck out of my finger). Fixing the wrench insulation I finished hooking up the new balancer.

Everything is hooked up and no faults on anything but now cell #3 is SUPER unstable. It will range from 3.6 to 2.9 volts every few seconds while charging. When I unhook the charger it will trip the BMS after less than an hour with low load.

If I shorted #2 why would #3 be showing as the problem? I've checked all the terminals and connections. If I unhook the loads can I "top balance" the pack as it is in the 48v configuration? I read someone suggesting moving the bad cell to see if the issue follows, I'll work on that and see what happens when I ((unhook the new balancer...) no change or worse).

Thanks in advance,

 

[sunshine_eggo]

Redo the BMS sense wire.

 

[RoamingTuRDle]

Well I have to admit I was a bit bothered by the "Redo the BMS sense wire." thing but in the end it was close to right. Of the 32 battery connections one managed to be not tight enough (bus bar between #2 & #3. Went through it all again (not for the second time) and the system has stabilized. Leaving the second balancer hooked up for now. Put the system through some testing yesterday and seems to be good.

Thank you,

 

[sunshine_eggo]

erratic voltage behavior is almost always a connection issue. Glad you got it sorted.