My new boat has 2 batteries that can be switched in case one is dead. I've got power at ny dock. Can I plug in one battery maintainer (tender) and wire accross to the second battery and keep both boosted or should I set up two tenders?
+1. you dont want to charge them at the same time, they wont charge evenly. you need to charge them seperately or get a 2 bank charger.You don't want to put one (simple) battery charger on two batteries, because those batteries will have different charging needs. I used two separate battery maintainers on my boat until I upgraded a few months ago to a dual channel onboard charger.