I have an all-Victron 12v system (diagram attached) with a MultiPlus II 2x120 and 4 100Ah LiFePO4 batteries installed in our RV. It has worked extremely well for 18 months, and this past weekend we had a problem with faulty power at our campsite power pedestal. I have an EMS permanently installed, and it did its job by preventing the power from entering the trailer.
We were in a hurry when setting up camp, and when the "pilot" light came on in my 50A plug I failed to double-check that the trailer was in fact receiving shore power. It was hot inside so I turned on both ACs, not knowing that they were being powered only by the inverter and batteries.
After a while, I happened to see that the MultiPlus was blinking low battery and I checked the GX Touch 50 to notice that the batteries were at 1%. I immediately turned off the ACs, fired up the generator, lowered the AC input current limit to 20A and plugged it in. By that time the lithium batteries had reached 0%. Once plugged in all was well with trailer power, and that evening they fixed the power pedestal so we plugged into 50A for the remainder of our trip.
When we broke camp to leave, I double-checked that the batteries had charged to 100% and displayed 14.4v. Once we unplugged from shore power, however, the slide moved very slowly and then stopped so I looked at the system and saw that while the battery was reading 100% the voltage was only 11.7v. I plugged back into power to retract the slides, and the battery voltage jumped back to 14.4v. Unplugging power the final time showed the batteries still at 100% and back down to 11.7v.
I'm unable to charge the batteries since they show 14.4v when plugged into shore or generator power, but they are virtually empty when unplugged despite showing 100%. I understand there is a possibility that running the batteries down to 0% may have damaged them, though I'm holding out hope that this is not the case. Is there a way to test for this? And if it's not a battery problem what are the troubleshooting steps I can go through to find the problem?
Sorry for the long post, and thanks in advance for any help you all can provide!