Semi automatic DC-AC power source

[anso-engineer]

Hello, I am working on project, where I have LFP 12.8V battery, invertor and charger. Everything should work in semiautomatic mode.

When there is voltage on charger it pulls relay and take measurements for charging to the MCU, mainly I am interested in estimation of delivdered power to the battery (shunt resistor and voltage divider).
When it pulled from the socket relays stays in NC and invertor works. There is button on invertor.

Further MCU 3V3 will be integrated, so I will be able to add some buzzers or other indication, but for now I think how it will work in general. All connection to relay will be through the wires. Logic elements will be located at PCB.

Charging current 15A.
Discharge current 50A at peak.

[anso-engineer]

I have some suspiction, that relay can fall in the latch state.