I have a on board charger for my trolling motor batteries I plug in at night after using them each day. Sometimes it takes longer than overnight to charge them up fully. Instead of cutting into the fishing day waiting on it to charge completely can I hook another charger to them at the same time? If so how would I hook it up to do both batteries? The charger I have is not a real powerful one more of a maintainer. I just don't want to have to spend the money right now on a bigger charger. Thanks