When I was up in Canada I finally got the chance to really do a good test on a new addition to the boat. This spring I installed a Dual Pro ProExtra ll on board charger, it hooks up to your trolling motor batteries and to your main starting battery. I also have a Dual Pro 4 bank charger for keeping the batteries topped out on land, but both units can be left wired up at the same time without any problems. On the water, once your main battery is charged the power from your outboard alternator is sent to your trolling batteries, in my case a 24 volt system. I never had starting or trolling battery problems the whole week.
I was amazed at how well it worked, we fished roughly 14 hours a day, of that I would say roughly 2 hours was running between spots and the rest was with the trolling motor. During the week my trolling batteries never read less than 22 volts! In previous years by the end of a heavy day of fishing the same batteries would get down to 17-18 volts.
If you want to take a look at these go to http://www.dualpro.com
just thought I would pass this on, maybe might help somebody else out or give them another option.