I have a MultiPlus Compact 24 | 1600 | 40-16. I’ve had it set up for three nights, and every night I have observed the following:
- AC in is off during the day. I turn on the inverter to use battery power, discharging to about 80% state of charge (according to the BMV-702 I have connected).
- AC power returns, and the inverter starts charging.
- At some point after charging for an hour or two, the inverter shuts down. The main switch on the front is still switched on.
- I switch the inverter off then on again, and normal functioning resumes.
In all instances the load would have been around 200 to 400 W maximum. There were no events other than the reaching of 100% state of charge that I can think could have triggered the shutdown.
Before the AC power returned this evening I checked the history in the BMV-702. It displayed the lowest battery voltage as 0.01 V. I cleared the history, then watched as the charge approached 100% this evening. It reached 100% and the fan in the inverter turned off, but AC out seemed to be normal. The voltage of the batteries was about 27.6 V and continued to climb to about 28.6 V, after which it dropped again to about 28.4 V I think. I can't be absolutely sure about these figures. Then after a minute or two the inverter cut off completely, as it had the previous two nights. There were no lights on, and no AC output. I switched it off and on again, and normal AC output returned. I checked the BMV-702 history, and it showed the lowest battery voltage as 26.3 V.
As I was typing this it cut off again. State of charge was 100%, battery voltage was as above, about 27.6 V and climbing up to 28.6 V, then dropping to around 28.4 V and staying there. As previously I switched it off and on again and normal functioning seems to have resumed.
I had my Victron dealer set up the inverter through VEConfigure (I don’t have the MKIII to USB cable). The batteries are two Blue Nova BN13V-108-1.4k LiFePO4 in series. They have an internal BMS. Their manual says the bulk and absorption voltages should be 14.2 V, and the float voltage 13.6 V. As far as I know this is what my dealer set in the configuration. They sold me these batteries, so they are familiar with them.
My system wiring is as in the diagram below, though I haven’t connected the solar panels yet.
I’d appreciate any insights into what the issue could be, or what else to try to diagnose it.