JBD BMS Relais Problem

jandb said:

OK need to check into this futherb after next week. I’m gone the whole week and decided to shut down the system completely.

BUT. I do not understand how the wrong setting inside the dvcc and BMS causes the relay of the BMS klick every second.

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This will do that:

jandb said:

PS. Last my cell OVP was set at 3,6V in the BMS and 57,6 (3,6 x 16) in the dvcc

Click to expand...

This is almost guaranteed to cause a problem.

Charge voltage must be below the cell OVP voltage. Did you alter the driver default voltage of 3.45V?

jandb said:

What I understand is that between the low voltages and about 3.8 - 3.9-ish volt there is no way to tell if cells are unbalanced. So why would the BMS start clicking?

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3.8-3.9 is over volt.

Voltage does not correlate with imbalance in the 3.1-3.4V range.

jandb said:

Also I was tricked by the voltage at low stages. Now I see I need to top balance better (next week). Beginners fault assuming that all batteries within one delivery batch are charged equally…

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Recommend you follow the guide.

sunshine_eggo said:

This will do that:

View attachment 149235




This is almost guaranteed to cause a problem.

Charge voltage must be below the cell OVP voltage. Did you alter the driver default voltage of 3.45V?




3.8-3.9 is over volt.

Voltage does not correlate with imbalance in the 3.1-3.4V range.



Recommend you follow the guide.

Click to expand...

I had the clicking also with all cell voltages around 3.2 to 3.4V (can’t remember exactly …) and overvoltage cutoff set at 3.7V and recover at 3.4V
So not only when the safety and recover were close to each other …

I had the battery pack top balanced again. At 3.6V per cell (approximately) I had a difference of max 10mV. Only 1 cell was a bit lower than the others. 15 cells were with a max difference of 2mV.

Safety settings on JBD BMS are set to max 3600mV and 3500mV recovery. On the low voltage safety at 2700mV and 2800mV recovery. This is on cell level. On battery pack level I have all similar values like 3600mV * 16 cells and so on.
Auto-balancing is set at 3450mV.

Victron is set at 55200mV max charge (3450mV per cell). No clue how to set low voltage stop on Victron, but I think I read somewhere that for a 48V pack the low voltage cutoff is 40V. But I can be wrong…

The relay on my BMS is still clicking every second. Whether charging or discharging. And this from about 3.3V per cell up to 3.4V. I haven’t charged back the pack completely since the last balancing.
I have no more ideas what to do to stop the relay from clicking.
Any ideas from your side ?

PS. Another strange behavior I noticed is that at night the cells discharge quite a lot. I disconnected BMS from Victron to verify and this confirmed my suspicion. Battery discharge, I suppose via the BMS. This shouldn’t be as auto-balancing didn’t kick in due to SOC below auto-balancing threshold . I suspect a loss inside the BMS which then also could cause the relay to click all the time… any thoughts on this?

Much appreciated

Sounds like a defective BMS.

sunshine_eggo said:

Sounds like a defective BMS.

Click to expand...

That’s what I’m trying to explain the vendor from AliExpress since more than a month but they keep saying I need to modify and re-modify settings. Apparently just to keep me busy.
Off course they refuse to admit it is faulty and reimburse me or replace the BMS. ?

I think I’m going to send them a copy of this discussion, if you don’t mind.