Battery switching without tears

On Wednesday, April 15, 2020 at 1:25:50 PM UTC-4, wrote:
I've seen a lot of recommendations to keep both batteries connected and not bother with switching. One reason I don't want to do that is that I have a couple of slim 2.3 Ah SLA batteries in the tail of my ASW 24 as a backup (yes, they fit--barely) and the usual LiFePO4 battery up front for the primary source. Ignoring the issues of batteries with different capacities and chemistries running in parallel, pulling out the tail battery pack every night and charging it is just another chore. At a contest, I never do unless I've had to go to it (only a few times in many decades). I'm lazy.

Chip Bearden
JB

Chip, your situation sure does call for a switch. Or two switches. Or two diodes. But certainly not simply in parallel. Note that with two diodes the "switching" would be automatic: as long as your LiFePO4 battery up front is not almost completely discharged, there would be no draw on the tail batteries since the diode between them and the "bus" would have a voltage on it in the "wrong" (non-conducting) direction.