Hooking up bat. isolater, 1980 35hp Johnson

15hpevinrude

Seaman Apprentice
Joined
Jul 3, 2010
Messages
33
Hi I just purchased a 93' 14' Discovery Voyager boat, with a 35 hp Johnson. I would like to add a second Bat. for the trolling motor, and other acc. It is an electric start model, so is it safe to assume that it has a charging circuit? I am trying to figure out where to connect the wire from the centre pin on the isolater. Do I just attach it to the pos. term. on the start solenoid? :confused:
 

R.Johnson

Rear Admiral
Joined
Sep 24, 2003
Messages
4,446
Re: Hooking up bat. isolater, 1980 35hp Johnson

I would just go for a deep cycle battery for any add on's. The charge system on your engine will keep up with charging the starter battery, and running lights', not much more. You should be able to find a deep cycle battery to fit your need's.
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,571
Re: Hooking up bat. isolater, 1980 35hp Johnson

You can rope start your engine so there is no danger of running down the starting battery. You simply do not have enough accessories to run it down with. The troller should be on a separate deep cvcle battery. Why bother with isolators or dual battery switches. The alternator doesn't have enough output to do much for the second battery. Spend the money on a dual bank charger and plug in at the dock.
 

15hpevinrude

Seaman Apprentice
Joined
Jul 3, 2010
Messages
33
Re: Hooking up bat. isolater, 1980 35hp Johnson

Thanks for the responses, I see this was moved from the Johnson forum. I posted it there because my question was Johnson specific. I am trying to find on my paticular model, where to attach the centre wire of the isolater. But since it electrical, I see why it was moved. I allready have a good deep cycle bat. for the acc. I am going to have a sterio, and trolling motor, so I know I will be wareing down that bat. And I know I can rope start my motor. BUT for safety reasons (bilge pump) etc. I want to be able to keep a good working bat.:)
 

boobie

Supreme Mariner
Joined
Nov 5, 2009
Messages
20,795
Re: Hooking up bat. isolater, 1980 35hp Johnson

I know a lot of electrical things have changed over the years but we were always told in the OMC service schools that you have to have a min of a 9 amp charging system to install a batter isolator.
 
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