2 batteries, two motors, 1 isolator switch

[Chris H]

Hi Can Any one give me some help, I've a 200hp merc electric start,and and 9.8 merc electric start, duel batteries one isolator, am I ok to hook up both to the Isolator or do I need seperate swiches, will the charging of the batteries from the 9.8 merc have any problems on the 200 merc and vice versa, I only run one motor at any one time

 

[ricksrster]

Re: 2 batteries, two motors, 1 isolator switch

 

[ricksrster]

Re: 2 batteries, two motors, 1 isolator switch

OOps! the above isn't right.
The diagram on the right.

 

[Chris H]

Re: 2 batteries, two motors, 1 isolator switch

Can only see half the diagram,So You are saying I have to have two isolator switches, I have two batteries with one isolator, so as I can switch between batteries for charging, I then have a kicker engine which I use for trolling,it is electric start and will charge the battary also

 

[Silvertip]

Re: 2 batteries, two motors, 1 isolator switch

The issue you need to be concerned about is not so much charging the batteries, but what happens to the charging system in the small motor when running the big engine. A wrong switch setting can back-feed that small engine charging system and simply overpower it. The big engine has a much higher alternator output so it could damage the small engine charging system

 

[gss036]

Re: 2 batteries, two motors, 1 isolator switch

I have a 1989 Merc 200 HP and a 1993 Honda 15 HP electric. I just have the Honda hooked to the closest battery and run a standard 3 way switch. I have never had any problems doing this. I use a remote electric/hydraulic steering system for the Honda and have never run a battery down.

 

[Silvertip]

Re: 2 batteries, two motors, 1 isolator switch

As I said, as long as you don't back feed the small motor it won't be a problem. But back feed a charging system containing components sized for a 6 amp system from a large engine with several times higher capacity than the small engine and components will fail.