Hi. I'm hoping some of you kind experts could tell me the steps I should go through to diagnose a battery problem. Pack is:
Headway 12Ah 12s1p with a capacity-based bms (pack made by evassemble.com). The pack worked well from day one and has gone through ~20 cycles, usually never below 60-80% capacity. My commute usually takes 4Ah from it. Although i have been careful to keep it well supported and upright, when taking it out of my battery/trunk bag, I have noticed a rattle and I suspect that the bms might not have been stuck down properly to the battery housing (That would fit with a few other half-arsed build problems from evassemble, like using what seems to be second-hand wire for the leads!)
After return from a ride, I put it on to charge (4A charger designed to cut off at 43.7v). At the end of the charge, I plugged in my watt meter and it read 41.7v. It's usually around that mark, so I presume that the bms cut off works before the charger's does. Once or twice I've got it to 42v but nothing higher. I plugged it in to the controller this morning but... nothing. Then I tried with the watt meter and nada. I suspected my crimping, but usually I can get a voltage reading off the in/charge line as well as the out/discharge line so tried the watt meter on there. Nothing. This suggests it wasn't one of my crimps and that it's something between cells and leads. Oddly, after removing the anderson housings and attaching the contacts to a volt meter I got a reading of 41.3v (there's often a slight difference between what my watt meter and volt meter state). The value was fluctuating but that might be because I never remember the right setting to use on the volt meter for DC current. I also don't understand the measurement of amps using a voltmeter, but turned it to 'A' and took a reading at 16.x. I was expecting 0 because it wasn't under load. Perhaps it was mA and I'll need to do test that again. However, I guess the pack could have overcharged and the bms might have tripped????
I've never had the battery pack out of its shrink wrap, so I'd appreciate if you could share the basic steps for diagnosing what the problem might be. Presumably testing each cell would help, along with (somewhow) testing voltage into and out of the bms to see if it's a bms problem?
A 'how to' diagnose a battery pack might be quite a useful thread for other relative noobs too, as the ES info on that seems to be inconsistent and spread across multiple threads. Cheers.
Headway 12Ah 12s1p with a capacity-based bms (pack made by evassemble.com). The pack worked well from day one and has gone through ~20 cycles, usually never below 60-80% capacity. My commute usually takes 4Ah from it. Although i have been careful to keep it well supported and upright, when taking it out of my battery/trunk bag, I have noticed a rattle and I suspect that the bms might not have been stuck down properly to the battery housing (That would fit with a few other half-arsed build problems from evassemble, like using what seems to be second-hand wire for the leads!)
After return from a ride, I put it on to charge (4A charger designed to cut off at 43.7v). At the end of the charge, I plugged in my watt meter and it read 41.7v. It's usually around that mark, so I presume that the bms cut off works before the charger's does. Once or twice I've got it to 42v but nothing higher. I plugged it in to the controller this morning but... nothing. Then I tried with the watt meter and nada. I suspected my crimping, but usually I can get a voltage reading off the in/charge line as well as the out/discharge line so tried the watt meter on there. Nothing. This suggests it wasn't one of my crimps and that it's something between cells and leads. Oddly, after removing the anderson housings and attaching the contacts to a volt meter I got a reading of 41.3v (there's often a slight difference between what my watt meter and volt meter state). The value was fluctuating but that might be because I never remember the right setting to use on the volt meter for DC current. I also don't understand the measurement of amps using a voltmeter, but turned it to 'A' and took a reading at 16.x. I was expecting 0 because it wasn't under load. Perhaps it was mA and I'll need to do test that again. However, I guess the pack could have overcharged and the bms might have tripped????
I've never had the battery pack out of its shrink wrap, so I'd appreciate if you could share the basic steps for diagnosing what the problem might be. Presumably testing each cell would help, along with (somewhow) testing voltage into and out of the bms to see if it's a bms problem?
A 'how to' diagnose a battery pack might be quite a useful thread for other relative noobs too, as the ES info on that seems to be inconsistent and spread across multiple threads. Cheers.
