New BMS Battery not working

[John Manning]

I have purchased from BMS battery in china a bike electrification kit. The battery pack is a 36v 10Ahr unit, I have charged it ,I think, for 36hrs. The battery level indicator does not light and there is no output, until I plug in the energized charger 42v output, then I get 41.6v at he output.
I have opened the unit up and across the battery pack is 41.6 volts. I can find this voltage on the bms unit. The unit does not match the one that I can find on the BMS website (small letters for battery management system, large letters for the Chinese manufacturer.)
I started this thread in "introduce yourself" but I think it more appropriate here.
Any ideas would be most welcome as without the high current source I can't check the rest of the conversion.
Regards
John M

 

[Deleted member 4366]

I asked you to tell us which battery it is. I also asked if it has a switch on it.

 

[John Manning]

Sorry, some info did not get transferred to the new thread. The battery is a LiPo type and the battery box has a switch which is in the negative lead just before the output socket. The web site calls it Li Ion (http://www.bmsbattery.com/36v/522-bottle-ebike-battery.html). The charger circuit appears to charge several groups of cells as in a series/parallel arrangement.
Regards
JohnM

 

[Deleted member 4366]

The switch is surely not on the output lead. It wouldn't be able to switch enough current. On all the ones I've seen before, the switch switches the BMS on/off, so you can't charge or discharge without it switched on. The fact that you get output when you plug in the charger means nothing. Turn off the switch when the charger's connected, and see if you still get output to confirm.

Does your BMS look like this. If not, can we have a photo?

 

[recumbyrider]

I have purchased from BMS battery in china a bike electrification kit. The battery pack is a 36v 10Ahr unit, I have charged it ,I think, for 36hrs. The battery level indicator does not light and there is no output, until I plug in the energized charger 42v output, then I get 41.6v at he output.
I have opened the unit up and across the battery pack is 41.6 volts. I can find this voltage on the bms unit. The unit does not match the one that I can find on the BMS website (small letters for battery management system, large letters for the Chinese manufacturer.)
I started this thread in "introduce yourself" but I think it more appropriate here.
Any ideas would be most welcome as without the high current source I can't check the rest of the conversion.
Regards
John M

I had a similar problem with a BMS Battery Lifepo4. It appeared after several months using the battery (not straight out of the box like your problem).

Same symptoms - when charger attached full voltage indicated, but nothing when charger removed. I contacted BMS Battery about the problem but got no reply. So eventually resorted to bypassing the bms for output (using an inline fuse on the positive wire), while continuing to charge via the bms.

Not exactly an ideal solution, but the battery has worked ok ever since (for the last couple of years).

 

[Deleted member 4366]

I guess that by now OP has found the switch.