I have a powerful system (can use up to 20A in max load when using batteries) that can be either powered by batteries, or when possible, by another power supply with the same voltage, so it stops draining the batteries. The problem that I encountered is I don't know how to swap between these sources without a huge power-loss (I don't want to use oring diodes because with 20A can produce a lot of heat).
Right now I have this setup being 11VU the auxiliar power supply, and 11VS the battery suply. I can use a diode with the auxiliar because it doesn't drain too much while in this state, but I'll be glad to accept any suggestions to change it. But I'm afraid that when 11VU connected, the power can return to 11VS by the MOSFET diode. What can I do?