I just bought a 24V Victron 1.3KW Multiplus inverter charger to run electronic gadgets and lights in my house. My battery bank is 4 units of flooded 360Ah usbattery 6V.
I am thinking of running a 2nd inverter on the same 24V battery bank to power my refrigerator and deep freezer, about 800W total. The 2nd inverter may be a xantrex inverter without charger function. Is it possible to design the system in such a manner that the 2nd inverter will only work when the battery SOC is between 90-70% and dropping? This is to prevent total depletion of the battery bank.

However, there may be issues with switchover to grid power when power is restored because the Xantrex inverter has no inbuilt changeover switch.
Any ideas how I can accomplish this?
 

@The Terrible Triplett has a device that he controls with a Victron BMV that changes over between grid and inverter. That sounds exactly like what you need. If you search on this forum you'll find some pictures of it.

@Mazs yes you can.

Using the BMV SOC and a few relays, switch the 2nd inverters output on / off based on set min/max SOC levels of the BMV.

I.e. if lower SOC is reached, system goes back to Eskom. Once high SOC is reached, system switches again to use inverter power.

To eliminate the 1sec break of the relays, I use a online UPS to keep the current stable and not dip when the switching takes place. Not the most efficient ito power usage but it is the most efficient solution I could get ito protection all I am powering.

After many many years, it is still working day in and day out.