I’ve got a 12V trollong motor on the bow and a 24V motor on the stearn and two deep cycle trolling batteries to run the motors. Before I had the 24V motor, I used to run the front motor on two batteries wired in parallel to extend the amount of running time on a charge for when I fishing for multiple days and cannot recharge. When wired for 24V, I could only run the 12V motor on a single battery. To fix this, I am thinking about buying some heavy duty connectors and wiring per the attached diagram. When plugged in parallel, both motors see 12V. When plugged for 24V, the 12V motor still sees 12V off of a single battery. Should be better for the batteries since they are always drawn from equally.
There have been a few posts out there on this subject in the past few months and this is an alternative to consider. Beats having to change the connections on the battery to switch back and forth.