installing two batteries

[Ilikesalmon]

Hi All, I have a 16' fish n ski boat with a 50hp Johnson. The boat has a single 12 volt battery located under the transom slash pan with the gas tank. I want to move the battery to under the front seat and I am thinking about installing a second battery for back-up. Can anyone tell me how to hook this up and also the gauge of the wire that I will need?

 

[--GQ--]

Re: installing two batteries

 

[Ilikesalmon]

Re: installing two batteries

Hey GQ, You da man! Thanks a million, Hope I can help you one of these days.

 

[ricksrster]

Re: installing two batteries

You might want to consider a combiner or an isolater with a 1 both 2 off switch to charge both batteries without one battery draining the other.

 

[--GQ--]

Re: installing two batteries

Yes you can Ilikesalmon, I've been looking for a Torque-Shift Prop for my Volvo Penta for sometime now to no avail. You want my shipping address? ....... just kidding. as you were.

 

[Ilikesalmon]

Re: installing two batteries

rickrster, Would I need an isolater if I had the switch only?<br /> <br />GQ, the prop will be under your Christmas tree, (you may have to look hard though!)

 

[ricksrster]

Re: installing two batteries

Yes you can. You can use a switch that has an off position, Battery 1 position, Both batteries position, And battery two position. Make sure it is the kind of switch that doesn't break the contact between the positions. You don't want to run your motor without it being connected to a battery. The isolater will only charge one battery at a time. It keeps the weaker battery from disharging the charged battery. There will be a slight voltage drop with an isolater. A combiner is the other way to go without the voltage drop.

 

[Ilikesalmon]

Re: installing two batteries

Thanks Man, you have been a big help to me. I know just about nothing about boat electronics.

 

[Silvertip]

Re: installing two batteries

For your application, forget the isolator and keep it simple. The term for the battery switch is "make-before-break" style. This means when switching, the contacts make (connect) before the current setting contacts break (disconnect). Just don't turn the switch to the OFF position with the engine running for the reasons pointed out in earlier posts.

 

[dmarkvid2]

Re: installing two batteries

Hi GQ, is that diagram good for any size boat?<br />I have a 22ft. cutty cabin with a 5.7 mercruiser.<br /> Thanks

 

[imported_Curmudgeon]

Re: installing two batteries

It's a good diagram, but I'd suggest one change: run the accessory positive lead from "COMMON". The diagram, as shown, doesn't allow Battery 2 (by itself) to power accessories. If you want a "hot" bilge pump, run it seperately to terminal 1 or 2.

 

[--GQ--]

Re: installing two batteries

Old Curmudgeon, good suggestion. The problem with it though with the switch in the OFF position, the bilge pump has no power. It's a good idea to keep power to your bilge pump at all time. Matter of fact its the most important item in your boat as far as safety.<br /><br />Mark, the diagram is for any size boat. Electricity runs on the same basic principle wether its a million volts ot 12 volts. It maybe a 15 foot or a 30 foot boat.

 

[QC]

Re: installing two batteries

I agree with GQ. A bilge pump with an auto switch should be wired directly to one of the two batteries . . .