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cell high voltage disconnect

frthompson

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May 29, 2021
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I have 2 12 volt batteries consisting of 4 eve 280 ah cells and a jbd bms in parallel and a victron multiplus charger. My cells seem to be behaving well and are very close in voltage. Balancing kicks in at 3.4 volts but cells are typically plus or minus 0.01 v. But at the very end of the bulk charge when switching to absorption one cell voltages diverge a little and one is going over the HVD which I have set at 3.65 v. My bulk absorb voltage is se a 14.3. Should I try dropping the bulk/absorb voltage? Float is set at 13.4. I did top balance prior to assembly and installation in my trailer--Frank
 
I have 2 12 volt batteries consisting of 4 eve 280 ah cells and a jbd bms in parallel and a victron multiplus charger. My cells seem to be behaving well and are very close in voltage. Balancing kicks in at 3.4 volts but cells are typically plus or minus 0.01 v. But at the very end of the bulk charge when switching to absorption one cell voltages diverge a little and one is going over the HVD which I have set at 3.65 v. My bulk absorb voltage is se a 14.3. Should I try dropping the bulk/absorb voltage? Float is set at 13.4. I did top balance prior to assembly and installation in my trailer--Frank
Yes set bulk/absorb lower.
Anything over 3.45 volts per cell will get your battery charged.
Higher voltages just get there quicker.
14.3 volts = 3.575 volts per cell.
Try 3.5 per which is 14.0 volts.
If you still get a cell over voltage disconnect you can lower it still.
After several charge cycles that don't trip the bms your pack should be better balanced and you can try raising the voltage again.
 
Thanks, that seems to be working. Its staying in the range where it can balance the cells a little better now without hitting the HVD.
 
When I tried it with bulk/absorb at 14.2 it did so set it to 14.0 and it does not hit the HVD. Running it though a few discharge charge cycles and each time cells are more balanced. So once the cells look reasonably balanced when at full charge, might try bumping up the bulk/absorb again to 14.3-14.4?
 
When I tried it with bulk/absorb at 14.2 it did so set it to 14.0 and it does not hit the HVD. Running it though a few discharge charge cycles and each time cells are more balanced. So once the cells look reasonably balanced when at full charge, might try bumping up the bulk/absorb again to 14.3-14.4?
Try it out.
If it disconnects titrate the charge voltage.
If it doesn't you are good to go.
 
Check all your connections. A bad connection can result in a voltage hot spot. Connections have to be clean, flat and tight.

I have the same setup. 280 Ah cells in 4s2p with 120 amp JBD BMS. I can charge the bank at 120 amps with no problems, but my charge voltage is set for no more than 14.2 volts.
 
Yes I would drop the charge voltage by 100 mV until this is resolved.
Then run it for at least a month and see if there is improvement.
Post the results.
 
So the cells seem balanced initially with delta of 0.001-0.005 but in the very last stage of bulk or just as it switched to absorb one or two cells on each battery would run up to 0.1 volts higher triggering the HDV. By dropping the bulk/absorb voltage and going through a few charge cycles and observing the jbd bms balancing things seem to be OK now. When discharging and for most of the charge cycle delta is 0.001 - 0.003, As each battery gets to 14 volts and switches to absorption the delta increases to 0.058 but cell voltages are below 3.55--see screen shot. After in float for awhile delta deceases back down to 0.001- 0.003. Still have bulk/absorb set to 14.0 v. So I will just try running it at these settings for awhile and see how it does--

cell balance.jpg
 
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