Originally Posted by iskess
RVOSD has an aux battery feature. It will drain from the battery with highest voltage.
That would help. I was thinking more of a stand-by fully charged battery that would become the power source and have the almost drained battery taken out of the circuit.
I figured a heavy duty relay or very small contactor controlled automatically from a Low Voltage alarm or manually using a aux output on the receiver.
This would be the same circuit used in power backup systems fed from two different sources. If the primary source failed or hit a trigger point the secondary would be put into the circuit and take over.
Just thinking out loud.