Bms overcharging

DIY Builds
#1

So quite recently I changed the batteries in my board to 5x 2s lipos. I have them connected to an 80a bestech BMS and a vesc.

For charging I use a 2A power brick. I have checked the voltages and noticed quite a large difference in one of them .

While riding I drained all the batteries until the bms cut off. And the voltages of each battery were:

15956655332727189163949318206494
159566553327271891639493182064944000×3000 3.32 MB

These voltages were after the first full discharge of the battery. I hadn’t ridded it much previously and so just charged it back to full.

After charging the completely drained battery back to full I checked the voltages. It seems that they are all much close except Battery 1. That looks to be too high.

15956656733585720085281674775327
159566567335857200852816747753274000×3000 2.92 MB

Furthermore the battery that seems to be overcharged may be slightly swelled, but I’m not sure

IMG_20200724_195757
IMG_20200724_1957573000×4000 1.95 MB
IMG_20200724_195809
IMG_20200724_1958093000×4000 1.88 MB
IMG_20200724_195747
IMG_20200724_1957473000×4000 1.71 MB

Should I just seperately use a lipo charger and balance that one cell with it? Any suggestions would be much appreciated. Thanks!

#2

I’d be worried that the first channel of the BMS has failed. You’re lucky it didn’t burst into flames. Lipo packs don’t handle overcharging very well. It does appear as though the pack has slightly expanded. I would replace that pack, and the BMS.

#3

Would I be able to get a replacement BMS?

#4

I would certainly try.