battery charging question

[fish fool]

New to outboard boats and have a few questions. Have a new to me boat with a 85 HP Johnson model #85ESL75E and a 8 HP mercury trolling motor. Have two batteries connected to a battery switch.

1. Should I use one battery for starting and running main motor then switch to other battery when trolling on small motor to run electronics/downriggers. Or leave battery switch on for both batteries at all times.

2. Does the Johnson have a alternator and if so can it keep both batteries charged if it only runs for 15 minutes on plane to and from fishing spots.

Thanks.

 

[CATransplant]

Re: battery charging question

Fifteen minutes of planing time isn't enough to put much of a charge on your batteries. If you're using accessories extensively, I think I'd separate the batteries, with one for starting only, and the other for accessories. That way, you won't run the risk of running your starting battery down, and can always jump from the other one, if necessary.

This will also protect both batteries from being discharged by a short or other malfunction.

If you trailer your boat, it's pretty easy to use a charger to keep the batteries fresh. It'd be a rare day when you ran them down.

 

[tashasdaddy]

Re: battery charging question

also are use charge your batteries, sitting in a discharged state, decreases their life. they prefer a full charge.

 

[fish fool]

Re: battery charging question

Thanks for the replies. Only had the boat out twice and the last time noticed downriggers were not getting enough power to bring cannonball up. So switched battery switch to "both" and it worked fine. Charged batteries when I came ashore, but have not been out since. Guess I'm just wondering if running downriggers, gps, fishfinder, radio is too much for a single battery? Also is there a way or product sold to make battery charging easier than having to remove batteries after every trip? Can I put charger on one battery with switch on "both" and charge both batteries at the same time?

 

[tashasdaddy]

Re: battery charging question

there are chargers for multiple batteries, moving to electrical.