MPII 3000 low voltage warning while 53V and `Low SOC shutdown` activated

Q&A and troubleshooting
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1

Hi all,

I have an off-grid situation with a DIY LiFePO4 battery and a MPII-48/3000. The battery is charged by a SmartSolar 150/35.
No Cerbo, no bus, no communication (yet).

All seemed to work fine until at some point the Inverter got into a Low Voltage warning and shut down. The battery never got below 53V (I log the information from the SmartSolar) and also the BMS didn’t log any problem.

The weird thing is that VictronConnect app shows the animation with an empty battery and 53.10V as value that it reads.
When I disable the Low SOC shutdown the MP starts inverting again, and all is fine again.

So the question is: what am I missing here? I can leave this option off, the BMS will protect the battery anyway but I find it confusing that the MP sees the voltage but still determines it is low?

2

Who ( in your opinion ) calculates SoC for you ?

You have no BMS connection and no Smartshunt.

So you must turn off the SoC shutdown and program a voltage shutdown in your MP.

And pls measure the voltage on the battery terminals of the MP with load, maybe you’re wiring is too thin, you have a faulty connector, fuse, circuit breaker ?

Have fun.

3

Ah… that is an interesting question :slight_smile:
I didn’t consider that the MP is considering some SOC which it doesn’t get from any outside source. As I mentioned: I have turned this option off and also all monitoring, as there is no need for it anyway.
My general thinking was more like: how can the MP think there is a low voltage when it clearly measures a voltage which is high enough.
And to your other remarks: cabling is fine. Fuses are fine. Voltages are fine, it is just a feature - which I think is on by default? - which I didn’t consider actually needs a SoC.
Although I wonder how the MP starts out without any problems and then at some points thinks there is a problem? The system was almost idle with only a very light load on it (35W or so) and the first few days it worked without issues… anyway… shunt is on the way (delayed order) and some other improvements soon so this won’t be a problem. I was mostly wondering…

Thanks @Ludo