So I am currently 3,000 miles from my boat and home. Wife and kids took her out on the 2021 mayden voyage and the batteries were acting weird. Both were tested and are good. Our switch is a perko Off/1/ALL/2 and they are unable to start the boat on battery 2.

I hadmy oldest son take my multimeter and put the switch on Both and check continuity across both positive terminals and it showed a dead short so we are good there. I then had him turn the switch to OFF and check positive of batt 1 to negative of batt 2 and vice versa and voltages were solid. I just can't figure out why they are unable to start the boat off of battery 2