Starting battery/trolling motor questions?

[chris63]

What kind of(Group) Marine starting battery will work best for a small 25hp Mercury?I want to mount the battery half way up the boat and the factory wires aren't long enough.What gauge wire should I use to extend them?Could I use a deep cycle for the starter and have a small trolling motor hooked to it as well to save on weight or is this a no-no?My 25 has a pull rope and electric start so if my battery is spent I can still start without pulling the cowling off.c63

[BobT]

Here's my experience.

I owned a Lund Rebel 16 with a 40hp evinrude with electric start for nearly 12 years. I had a 40pd electric on that boat too. I used one dual-purpose battery for all my electrical needs. I got away with it because the outboard was easy enough to start if per chance I ran the battery down using the electric. That worked for me because it was rare that I ran that battery down so deep that it didn't have enough left to start the outboard.

I personally would not recommend doing this. The main reason is because it can be very hard on the battery to deep cycle it so far down between charges. The life of the battery will be diminished in this way. It is best to run your electric motor on its own deep cycle battery and then use a dual-purpose battery for the outboard and other electronics such as lights, bilge pump, aerator pumps, sonar, etc.