I have a Rec Active BMS with a 3P4S EVE 308Ah setup on my sailboat. I installed the system last October, all 12 cells were top balanced to 3.65 before installing.
About a month ago I noticed cell 4 voltage started to drop slowly, but only being about a tenth of a volt off so I wasn't too concerned. I checked all the cells with a mulimeter and couldn't find a discrepancy. I reset the BMS and the cell voltage read normally again.
Today I was motoring and noticed the AC power had cut out, turns out cell 4 is now reading 2.8, 0.6 volts below the other cells so the BMS and Victron Cerbo shut everything down. In the logs I got Error 7 temp too low for charging, Error 2 Cell voltage is below the maximum set threshold, Error 3 Cell voltages differ more than set threshold. Again I checked all the cells with my multimeter (reads to 3 decimals) and couldn't find any discrepancy. I reset the BMS and the cell voltages all matched within 3 tenths of a volt.
I live aboard and am cruising in the Caribbean, I've been checking voltages all day and it seems fine now. Anyone have any ideas? I was tempted to say solar flares except for the fact that it started a month ago. Let me know if there is anymore info I can share to get to the bottom of this. Also is there a tech support line I can call? This is the only avenue I am currently aware of.
Thanks!
It sounds like it may be one of 3 issues:
- First power down the BMS, remove the AMP connector so you don't damage the BMS circuitry and check for a loose or corroded connection somewhere like on the pins, within a crimp connector, or at the terminals
- Make sure there are no A/C power lines anywhere close to your BMS causing induced voltage errors
- Remove any network devices that may be causing a ground loop and see if the problem goes away.
- Using a #10 torx driver, remove the cover of the BMS and look for corrosion on the PCB or terminals
Thanks @Rick. There are no A/C lines anywhere nearby. Would you mind explaining a bit more about network devices that might be causing a ground loop?
I will take the connector off and check for bad connections.
The BMS is mounted in a very dry area alongside the cerbo gx, wakespeed 500, and two smart mppt's. I would not expect to find corrosion inside but will check that as well.
Sure, you can have a different ground potential across your boat, especially if you have some things bonded (connected to an anode) and that ground difference can induce an offset. A non-isolate ground can carry that voltage difference from one area of the boat to another.
Like item 4, its very rare, but an easy thing to check simply by disconnecting it
Also a bad connection on a boat can really cause havoc as you end up with galavnically induced voltages throwing things off when reading very accurate low voltages.
Galvanic adjective
-
Of or relating to direct-current electricity, especially when produced chemically.
@Rick Hi Rick I have not been able to resolve this other than narrowing it down to a faulty connection with the AMP connector. Is there a warranty that would replace the wirring harness?
Ok Trevor, we can do that for you. Please contact us at support@ogm-energy.com and we'll get you fixed up.
