Looking for answers on what could be the issue with our Victron system...(3x 200Ah "Smart" lithium batts with Victron BMS, BatteryProtect, BMV and Color GX monitors, Quattro inverter/charger, MPPT controllers, etc.....all Victron).
A couple of weeks ago, we were hit by a heavy squall, with 35-40kn true wind on the nose, in large confused seas. The autopilot, an NKE driving an L&S hydraulic ram was struggling with the excessive weather helm. Just as we were preparing to put in a 3rd reef, the entire boat "went dark" without warning. No autopilot, instruments, gps, radio comms, or lights.....all 12v circuits on the boat were dead! And just as we really wanted the autopilot to keep driving as we tucked in another reef. The boat was on her ear, (we later found seaweed draped over the leeward lifeline!!!). As we struggled to regain control, all of a sudden the boat "lit up".....all 12 volt circuits started up again!!! YEE HAH!!! we did a quick happy dance!!! But our happiness was short lived, as the cycle of off/on happened 3 more times over the next hour or so. Visibility was very poor, as the rain got heavier. We started the motor (it has a dedicated starter battery) and dropped the mainsail for the last bit of the overflows. At last we rounded the Mull of Galloway and gladly headed north. Conditions have been comparitively mild since then, and the problem has not recurred.
So what happened to our electrical system? After all, having the boat shut down like that at the wrong time could be disastrous. Had this occurred at night, in shipping lanes, ships tracking us on AIS or visually by our lights would not have known we were out there. And similarly, we would have been "blind" without radar or AIS to spot ships. While we still have no definitive answer, at this point all signs point to the Battery Management System (BMS) of the lithium battery installation. It's the only thing which would shut off all of the loads like this. The job of the BMS is obviously to protect the batteries, and will shut down all loads on the system if it senses low overall system battery voltage, overheating of the batteries, or cell imbalance between individual cells in the batteries.
According to the installing electrician/dealer, he feels that the system was "operating normally"!!! That given the struggle of the autopilot in these wind/sea conditions, it is possible that the demands on the battery bank MAY have caused a cell imbalance which caused the BMS to shutdown, even though the overall battery voltage was fine (we'd been charging while hooked to shore power for 3 days so had been 100% only 2 hours earlier).
I am having a hard time thinking of this as "normal operation". Normal operation of critical systems cannot simply shut down without warning, or the system is not suited for purpose!!!!! And also that a cell imbalance could have been brought on by excessive load on the batts. (the autopilot only requires a 30 amp breaker....at 12v, that's just 360 watts, .05c, far less than the load imposed by an induction hob or microwave which we often use for longer periods through the inverter without effect.). While of course I was a bit too busy to check the individual cell voltages with VictronConnect during the shut down, whenever I check the voltages at other times, the 12 cells are all within .01 volt of one another. Any ideas of what could have caused this shut down (it has not happened since)??? And what could prevent it in the future? I am thinking of installing a battery switch in parallel with the terminals of the BatteryProtect relay, normally kept open, in case of another emergency shutdown, though I have been advised that it's use could void the warranty! Any suggestions are welcome!
