How to Use Diodes to Have Two Batteries Power a Circuit with No Feedback

Question:

I would like to run a device off both batteries at all times w/o tying them together for other devices unless my battery switch is in the all position would one rm790 accomplish this as in red drawing or do I need two as in black drawing?

asked by: Josh

Expert Reply:

Your black drawing would be how wire up the # RM-790 so that both batteries would be on the same circuit but with feedback prevented on the circuits back to the batteries or having them tied together.

Basically you would use a diode on each battery line. Using one diode for both batteries would only allow one battery to power the circuit at a time.

expert reply by: Jameson C