I've recently added another fish finder so now I've got an SI fish finder mounted at my console and a DI at the trolling motor. Generally I like to leave both running while I'm trolling, but the problem is that my SI is tied into my cranking battery at the fuse panel. Is there any "trick" to use so I don't drain my cranking battery and get stuck on the lake? Was out fishing all day not long ago and thought I wasn't going to get it started. The only option I can think of is to re-wire it to my trolling batteries (I'm running 2 in parallel) but I didn't know if maybe anyone had any tricks I didn't know. I'm trying to avoid pulling any more from my trolling batteries, and I don't have room to add any more batteries. The other option I guess would be to start my big motor more, but I generally don't run it long enough to do much charging. Is there any way to rig up some sort of onboard charger or alternator to charge one battery off of another (or something like that)?