Battery not charging via charger but does via power supply?

[MangDav]

So I have a 36v battery that appeared to be working just fine and has been for the past 2 years. When I plugged it in to the charger which is a 42v 2A, normally it would change from green light to red to indicate charging but at the moment it just flickers between green and red. I measured the battery voltage and it was 36.4v so I probed the charge port and hooked up a power supply to it, put the power supply at 37v and the battery was pulling just under 1A. I probed the charger output with a multimeter and the voltage jumps around between 37v and 41v which I'm not sure if it's normal when it doesn't have a load, I unfortunately don't have a way to measure the charger voltage when it's plugged into the battery without cutting and splicing.

Would this mean the charger is faulty since the battery is pulling power when plugged in via power supply or are cells out of balance which is causing the BMS to cut charging but it can't cut charging when power supply is hooked up so it's taking charge regardless?

 

[ak136]

Which bms are you using?

 

[fechter]

Yes, sounds like a charger problem. If the battery had a bad cell group, the BMS would prevent charging even with a power supply. One test would be to try charging through the discharge port on the battery (via the controller power wires) just to rule out the BMS being the problem.