Help troubleshooting 48v system shutting down

[sprinter99]

Looking for help troubleshooting.

We are on a fully electric sailboat (everything electrical related done by me on the boat)

Worked great for 3 years. Past 3 days I've been having issues at night. Whole system shuts down.

I have a 48v (eve cells) 280ah with Daly 300a bms and when the system shut down my bms shut down as well (can't see Bluetooth info as well)

I can only restart it by removing the bms cables and replugging them (small cables that go to each cells)

But the real head scratcher is, my victron quattro was turned off when the shut down happens but if I don't shut off the circuit breaker to the quattro when restarting the system, my voltage is all over the place for a minute or so. (28-40v)

Is my quattro fried or bms or a short circuit somewhere ?

I'm going to try to shut off the inverter circuit breaker tonight if it happens again..

Pretty confused.

Picture of the system shutting down and when restarting it, the messed up voltage is not recorded which is weird because I was seeing it on the shunt when happening live.

 

[Q-Dog]

If voltage is jumping around I would suspect a poor connection somewhere.

Can you isolate the battery from the system to check cell voltages?

 

[sprinter99]

If voltage is jumping around I would suspect a poor connection somewhere.

Can you isolate the battery from the system to check cell voltages?

Voltage is just jumping around (sometimes, not Everytime the system turned off) when I turn the system back on AND the circuit breaker for the quattro is engaged. As soon as I disengage the circuit breaker everything is stable.

 

[littleharbor2]

Sounds like a loose connection somewhere.