Alternate battery switching module
First you need to find a relay that rated 24 V/80 A (or higher current) and then wiring should be like this:







simulate this circuit &ndash; Schematic created using CircuitLab

When V1 is connected it will energize the relay and your "equipment" get its power from V1 and when disconnected relay will switch to V2.

You probably have some capacitors at the power outputs which will prevent the relay millisecond connect/disconnect delay interrupt the power.