3 batteries with twin engines

[MakoNY]

I just got a new boat with twin outboards on it and there are 3 batteries. A Port, Starboard and a House, all 3 on their own switches. The PO was running all 3 batts in the ALL position on each switch.

I just wanted to make sure this was correct or if I should be running them in different positions, like Port on 1, Starboard on 2 and the House on either 1 or 2, or if leaving all 3 of them on ALL is fine.

The engines are '04 200hp Evinrude DI's, if it makes any difference.

Thanks.

 

[blackhawk180]

Re: 3 batteries with twin engines

Before someone else asks...... PICS?

 

[Don S]

Re: 3 batteries with twin engines

More than a picture, we need a wiring diagram of how the switches are wired to the batteries and to which terminals on which switch.

 

[Don S]

Re: 3 batteries with twin engines

Just to make it a bit easier, print this out and pencil in the positive wires only going from and too the switches.
No need for the negative wires. They all end up together sooner or later.
After you get them in, scan it and post hit here. Then we will know exactly what you have and how it works.

View attachment MakoNY.pdf

 

[MakoNY]

Re: 3 batteries with twin engines

Thanks for that diagram Don. I will take a look at it tonight or tomorrow and see if I can figure it out.

Do you by any chance have that same diagram showing how the wiring should look if it's correct? Sorry to ask but I am not all that familiar with what I'd be looking at in there, and I've never had a boat with twin engines and 3 batteries.

The PO told me just to run all 3 switches on ALL but a friend of mine said that isn't correct and will cause some kind of damage to the engines.

I can only assume it is wired correctly, but I really shouldn't assume anything with a boat from '96. I haven't had any issues when running it with all 3 switches on ALL, but I'd like to prevent any issues from doing something wrong.

My friend has twins and he runs one on 1 and one on 2, but he only has 2 switches and his House batt is connected with one of the others two, not like mine with the separate switch. Not sure I understand why it would be on it's own switch.

Maybe if I saw a diagram of how it should look it would help me to understand.

 

[Don S]

Re: 3 batteries with twin engines

Maybe if I saw a diagram of how it should look it would help me to understand.

I don't have a clue how using 3 switches with 3 batteries and 2 engine should be hooked up. Doesn't even matter if your's isn't wired like that.

My diagram is not a wiring diagram, No wires !!!!
Just something for you to print off so you can draw in where the battery cables go. Nothing else.

The PO told me just to run all 3 switches on ALL but a friend of mine said that isn't correct and will cause some kind of damage to the engines.

That means neither one knows how to use it.

 

[MakoNY]

Re: 3 batteries with twin engines

Ok Don I pulled the switches off last night and traced everything out and put it all into your diagram. Let me know what you think.

It looks to me like I should be running each engine switch on #1 and the House switch on #2 to draw off of the House Batt, but can also draw off the Stbd starting batt for the house if I wanted. Not sure how the House Batt gets charged, unless putting the House Switch on ALL will allow charging from the Stbd engine to to go into the House Batt..


View attachment Battery Wiring.pdf

 

[Don S]

Re: 3 batteries with twin engines

When running, you would want the engine switches in the 1 position, but would have to put the house switch to both if you want that battery to be charged too.
If you have the house switch on 2, it will not be charging while the engines are running.

 

[MakoNY]

Re: 3 batteries with twin engines

Thanks Don. So since the previous owner ran both engine switches on ALL or BOTH all the time, would that have caused any issues with the engines at all? I've read that if you have two charging systems competing like that it will eventually damage something in the charging system of one or both.

I also noticed that there is a wire from the Stbd #1 terminal to the Port #2, so you can access the Stbd batt from the Port switch. But then saw that there is a wire from the #2 terminal of the Stbd switch to the Common on the Port switch. I guess that would allow access to the Port batt from the Stbd switch but would it be any better to have that wire just going to the #1 terminal on the Port switch rather than the Common?

Thanks again for the help.

 

[Don S]

Re: 3 batteries with twin engines

So since the previous owner ran both engine switches on ALL or BOTH all the time, would that have caused any issues with the engines at all? I've read that if you have two charging systems competing like that it will eventually damage something in the charging system of one or both.

Shouldn't hurt anything at all.

Is one way better than the other??? I have no clue, you get the same basic results either way.

 

[MakoNY]

Re: 3 batteries with twin engines

Ok great. Thanks for the help Don, it's much appreciated.