Charging an Electric Trolling Motor

fisheromen · 07-04-2009, 07:16 AM

I have a 14.5' Aluminum boat that came with a trolling motor the original owner never set up or used. It is a Motorguide 30 which will be fine for putting around shooting carp and chasing bass (I have used the boat several years for salmon but miss warmwater fishing a little).

The boat has a 40hp Nissan with a starting battery. Can I just put a deep cell next to the starting battery and hook them up in tandem? Do I need to keep them separate and how would I do that? Is using the motor to charge the trolling battery enough or am I just dreaming with that? Just buying the battery will be more than I want to spend right now so I'm hoping I don't need an onboard charger. I don't anticipate a heavy draw - no fishing in current or using the motor to get places.

Any help would be appreciated.

Steve

stevo · 07-04-2009, 07:43 AM

Steve,
You can get a non onboard charger for not alot of money. I got one that worked fine from an ifisher for $20. A group 27 deep cycle battery will pull your boat around for quite a while on a full charge, esp if you stay below 3/4 throttle, WOT draws alot of juice.
To do what you are asking you'd need the batteries connected in parallel, I doubt your 40hp would charge either very well. ALso Starting batteries and deep cycles require different charging sequences for optimal charge and battery life.
Good luck

Starfish · 07-04-2009, 09:00 AM

Definitely I would not recommend connecting the batteries in parallel and then running an electric trolling motor off one of them. If you do that then both batteries will get discharged by the electric trolling motor and you'll find yourself with a dead starter battery. You really should just use a stand-alone deep cycle battery for the trolling motor and nothing else. Use a battery charger as Stevo suggested or better yet install an onboard charger to top it up after every trip. Keeping the battery fully charged at all times is key to extending the life of a lead-acid battery. Deep cycle batteries are more capable of surviving a full discharge than other batteries but they still do not "like" it.

Lead Bouncer · 07-04-2009, 10:05 PM

Dont connect them and do not try and charge the deep cycle off the outboard. It doesnt put out enough to charge your starting battery, if the stop and start are demanding. Ive replaced two starting batteries in a year, before I figured it out. 8-9 amps is about all you can expect from your outboard.

A deep cycle is meant to be drawn down and recharged. the starter is not.