Inverter beeping

[Kwest364]

When sun goes down, solar inverter starts beeping and charge controller says "fault prompt: battery over-discharge protection".

How/why are batteries overdischarging? Batteries dead? Solar sucks? Where to start? Troubleshooting?

Bought built out from previous owner. Obviously, something sucks with the solar. He said separate solar systems (DC and AC). Not sure which panels go to what, and which outlets run off of which system. I THINK 4 batteries for AC system, and 2 for DC system. Would seem to make the most sense since AC stuff inside bus requires more power.
Ex. While inverter is beeping, fridge and charging outlets don't work, but led lights do.


Attached pics:

[Rucker]

Can't tell if you have a battery management system (BMS). That's what shuts off the charge to the battery (and prevents damage).

Your solar charge controllers must be configured for the type of battery you have. Find the owners manual, read it and check your settings.

Keep us posted.