BMS balance wire shorted. Likely damaged BMS, or still good to go?

My 14s pack was put together, BMS connected, and ready to go for wrapping.
This is when i decided i should use some more hot glue on the balance wires before wrapping to prevent any rubbing over time and risk a short. This is the BMS type I'm using: https://www.ebay.com/itm/BMS-PCB-PCM-for-50-4V-14S-Li-Ion-Battery-Pack-45A-Drain-Rate-w-Balance-Function/172971369981

All went fine with the + leads for all 14 cells, but what i didn't know was that my hot glue was now warmer then the melting point of the wire insulation. This lead to a short between the GND balance wire and the final + terminal.
The wire section vaporized in a flash, and i was sure the BMS would be dead at this point - after having received +50V to the GND balance lead.

Much to my surprise, it appeared the BMS was still functional. There was only a connection between C- and B- when the balance leads were connected, indication it must have detected 2,8-4.2v on all balance leads.

Now here's where i did my big mistake...
While i checked that it would both take charge and discharge without issues, i completely forgot to check the balance and overcharge function of the BMS before i wrapped it in, put it in the battery box, and glued it shut...
At this point i have no way to check the actual cell voltage without literally cutting the box open.

Do you guys think it's likely that the balance and/or overcharge protection could still have been damaged from this, even though the BMS appears to work fine?

Most likely this will still work. But i wouldn't trust it w/o testing it in real life. A BMS you can't trust is worth NOTHING.

izeman said:

A BMS you can't trust is worth NOTHING.

Click to expand...

I think have to agree with that actually. So, i guess there are two tests i could do then.
1) Discharge the battery and see if it turns off when it should, and
2) overcharge to see if it turns off when it should. Or
3) simply replace the BMS when i've cut open the box anyway... And maybe order a bluetooth BMS so i can monitor the cells at the same time.

Or just cut open the box and test the cells.

1: Discharge to LVC, but not much under the cutoff voltage if it goes past LVC.
2:Then charge as usual and monitor if it stops at full charge. This is a very important test to monitor as over charged cells will be dangerous.
3: check the balance wires on the bms to see if the cells are balanced.

Or you could leave your current battery all glued together in the box and hope that it won't catch fire.

I say open it up carefully and check again.

e-beach said:

1: Discharge to LVC, but not much under the cutoff voltage if it goes past LVC.
2:Then charge as usual and monitor if it stops at full charge. This is a very important test to monitor as over charged cells will be dangerous.
3: check the balance wires on the bms to see if the cells are balanced.

Click to expand...

I guess i could simply connect the BMS to 14s of capacitors to test this safe and quick? 22000µF caps should be large enough to test both discharge, overcharge and balance i suppose? Would give a very quick answer without risking to damage any cells.
Checking undercharge, overcharge and balance for each balance lead on my 28Ah pack would be, well, time-consuming to say at least...

How would this CAP test look like? Could you post a schematic? I don't see how connecting a capacitor between two balance wire would do anything helpful to test the BMS.

Do you still have access to the balance wires? Or are they sealed inside the battery.

izeman said:

How would this CAP test look like? Could you post a schematic? I don't see how connecting a capacitor between two balance wire would do anything helpful to test the BMS.

Click to expand...

Cap test would look identical to a normal 14s1p pack. The capacitors would replace the cells as they won't cause any danger with overcharge, and they will make testing every balance lead on the BMS quickly.

My plan was simply hook it up like a battery with a spare set of balance leads and charge it with a power supply, then test each balance lead by:
1) Connecting a resistor on the cap to pull it below 2.8V and verify BMS disconnects load, then recharge that cap and proceed to next one.
2) Leave a low current power supply connected to simulate charging, and manually pull cap above 4.3v with a separate power supply to simulate cell overcharge and verify BMS disconnects charger, then discharge cap and proceed to next one.
3) Charge all caps to 4.3V, disconnect power supply, and verify all caps are being pulled back down to 4.2V to verify working discharge resistor for every balance lead.

e-beach said:

Do you still have access to the balance wires? Or are they sealed inside the battery.

Click to expand...

Unfortunately they're sealed off, but i think i'll just have to cut the box open again to test the BMS before i can trust it.