I started my system 5 1/2 years ago with 3 Battery packs of LEOCH 48100-TB. So far satisfying performance with no problems, set aside the little flaw of SOC calculation neglecting internal losses. They accumulated meanwhile 1831, 1649 and 1560 cycles, still displaying 100% SOH. I monitor them trough a RS485 bus connected to the laptop in my office.

Some days ago pack 2 disconnected itself from the 48V bus after being completely charged to 53V bulk charge voltage. It just sat there with no current in or out, 100% SOC, no alarm, no fault, no protect status. I checked the built in breaker but no trip. So it got to be the switching transistor failing. I started to figure out how to eventually short circuit it in order to make the pack operational again. But then I thought to try the BMS reset, it couldn't do any harm. I never had to use it before. I waited the other packs to get fully charged in order to minimize equalization current. The reset has to be hold for a few seconds until all LEDs have gone trough cycling. Then WOW, a quit high current occurred but gradually came down to normal. Bingo the pack worked again. However I noticed in this very same cycle pack 3 disconnected. I did the reset on it the following day and it also got back to normal operation. I wouldn't be surprised to experience the same with pack 1.

Is there any one of you BMS experts that can explain what really happened?

Hi @Beat

Not sure what type of BMS is in the battery pack. To me it sounds like what I experienced with JBD BMSs when cell over voltage occurred. Even after the over voltage was cleared, the BMS did not reconnect by itself. I had to force it to so manually by isolating it from the other packs and then drawing current (resistance between the terminals). As soon as I connected the resistor, I heard the internal relay click and it was working as normally.

The way I solved it in the long run, was by setting the charge voltage never to be higher than 55.6V (3.475V per cell) during Bulk or Boost (current charge phase) and 54V (3.375V per cell) during float.

Although in your situation no alarms were showing at the time, it might have cleared already.

Not an exact answer but al least an possibility... 🤠

55 minutes ago, DeonBez said:

Hi @Beat

Not sure what type of BMS is in the battery pack. To me it sounds like what I experienced with JBD BMSs when cell over voltage occurred. Even after the over voltage was cleared, the BMS did not reconnect by itself. I had to force it to so manually by isolating it from the other packs and then drawing current (resistance between the terminals). As soon as I connected the resistor, I heard the internal relay click and it was working as normally.

The way I solved it in the long run, was by setting the charge voltage never to be higher than 55.6V (3.475V per cell) during Bulk or Boost (current charge phase) and 54V (3.375V per cell) during float.

Although in your situation no alarms were showing at the time, it might have cleared already.

Not an exact answer but al least an possibility... 🤠

Just on your experience normally once you reach OV protection the voltage must drop quite a bit before resetting as you found when you manually discharged. Acceptable OV can be 3.6+ and a reset of 3.4V for phosphate cells. That is the guide line from JK BMS.

Tank you both for your thoughts. For your information I read from the BMS parameter settings: Cell OV protect is set to 3.65V, the OVP release at 3.38V.

@DeonBez In your case perhaps a reset would also have done the trick. But your bulk and float charge settings are correct for 16 cells as recommended by the battery manufacturer. In my case with 15 cells bulk 53V, float 51.5V.

Edited January 18Jan 18 by Beat

7 hours ago, Beat said:

Tank you both for your thoughts. For your information I read from the BMS parameter settings: Cell OV protect is set to 3.65V, the OVP release at 3.38V.

@DeonBez In your case perhaps a reset would also have done the trick. But your bulk and float charge settings are correct for 16 cells as recommended by the battery manufacturer. In my case with 15 cells bulk 53V, float 51.5V.

@Beat if the situation repeats, you do not have much to lose by setting the charge settings a bit lower for a test period. I would recommend trying bulk at 52V (or 51.5V) and float at 50.5V.
Hope you come right.