Spiky/Sporadic Voltage Values on Cell 1 (Connection Issue or Runaway Cell??)

[dezfutak]

I've just noticed that cell1 in my DIY Battery is not stable compared to the other cells - it seems be to randomly shooting up, and then going back to a normal operating range, even when under load, as you can see from the attached images. I'm currently diving in to other related threads where others might have experienced something similar, but if you have *direct* experience with this & some possible solutions, feedback would be gratefully received.

 

[DThames]

If the pack is easy to reconfigure, swap two cells and see if it is indeed the cell or something related to the charging or wiring. That might kill off a few of the wild geese.

 

[dezfutak]

If the pack is easy to reconfigure, swap two cells and see if it is indeed the cell or something related to the charging or wiring. That might kill off a few of the wild geese.

Great idea - will give that a go. I might also just re-check the connections before doing that too, just in case Cell 1's BMS lead or busbar connections aren't sufficiently tight. (I torqued the cell/bus connections to 5NM, but the BMS leads had to be hand-tightened, so human error on that front is a distinct possibility!)

 

[dezfutak]

*Update*: I've just measured the BMS sensor to BMS sensor lead voltages directly for all 16 cells, and they're ALL agreeing with each other (including cell 1!), within 3 mV of each other, so my conclusion is that the JKBMS isn't telling the truth; I kind of knew that already, as the JK BMS SOC reporting seems to go a bit haywire from time to time: