36volt BMS board help

[Deleted member 4366]

Very frustrating that you don't give the information that I require.

Put the charger away. Measure the voltage across the two thick wires that come from the cell-pack. Then measure between the cell-pack ground and each of the pins on the multi-pin connector.

If you already did that, your battery is totally knackered, which would be very unusual, seeing as it's protected by a BMS. It's not uncommon to get a few bad cells, but I don't think I've ever seen one that bad, which makes me suspicious about the measurements.

 

[craigp]

here are the voltages after being disconnected overnight

Main Battery Terminals - 6.22v

Pin 1 - ground
Pin 2 - 2.127v
Pin 3 -1.759v
Pin 4 -1.720v
Pin 5 -1.716v
Pin 6 - 5.04v
Pin 7 -8.35v
Pin 8 -8.24v
Pin 9 -8.24v
Pin 10 - 8.24v
Pin 11 - 8.17v
Pin 12 -6.46v
Pin 13 -6.22v

 

[Alan Quay]

Those are some very strange results.

I'm wondering about your meter. Can you check it by measuring something like an AA battery?

I have seen 18650's giving out high voltages before when faulty. I had one that was giving about 7v. Perhaps the pack has suffered some kind of electrical trauma causing mass cell failure?




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[craigp]

Those are some very strange results.

I'm wondering about your meter. Can you check it by measuring something like an AA battery?

I have seen 18650's giving out high voltages before when faulty. I had one that was giving about 7v. Perhaps the pack has suffered some kind of electrical trauma causing mass cell failure?




Sent from my HTC One_M8 using Tapatalk

My meter is working correctly. I checked it yesterday using my dc bench power supply. I have just checked some of the voltages again and they are discharging themselves. the main battery voltage is now down to 4.8v
I'm guessing there is some short circuit in either the bms or the cells themselves.

Can someone confirm what the voltages should be on each of the 13 pins of the bms connector?

thanks

 

[Deleted member 4366]

If those results are correct, the battery is total scrap. Nothing can be recovered from it. Take it down the tip.

The voltages should be 0, 4.15, 8.3, 12.45,..............., 41.5
Any good cell will show a jump of 4.15v from one pin to the next, except the two pins not connected.

The symptoms are consistent with the cell-pack being drained down to 0v and held there. Only the vendor knows how that could have happened. Normally, the BMS would prevent that.