I'm looking to combine the 2 circuits shown in the picture below using a switch.(ON-OFF-ON) I would like to keep the 12V output seperate from the 24V output. This is to maximize efficiency when using 12V with the added possibility of using 24V and 12V at the same time.
Switching 2 batteries from series to parallel with one output using a DPDT switch seems logical to me, but combining 3 batteries in the desired way is a bit overwhelming because in my attempts there's always a short.
edit: my problem: I have 3 battery mounts on a camera system with interchangeable batteries (sometimes I only use 2 batteries, sometimes 3 because weight distribution is important, all are charged seperately). I need a 12V out all the time and sometimes 24V. I would like to discharge all batteries as evenly as possible.