besides an on board charger, what is the best way to charge a battery while in use. i have a 13 ft aluminum boat that i use on electric only lakes, and want to be able to get the most out of my time on the lake by not having to deal much with batteries. i had planned to use 2 batteries and, while using one have the other on a solar panel charger to recharge it . however i have been researching the panels and have learned that they are not meant to charge a dead battery, but i am not sure if they will recharge a partial/used dead battery. any suggestions? maybe a good battery to use? and how much do the newer trolling motors that claim to "use the battery more efficiently" work?