2 outboards, 1 battery

coolbri70

Lieutenant Commander
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Oct 6, 2011
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1,554
:help:likely dumb question:facepalm: i have a 79 evinrude 85hp on my boat, adding 94 evinrude 15hp kicker, both have electric start and charging systems. can i just hook up the 2 wires from the 15 to my same battery:confused: just want to make sure they won't hurt each others electronics. i know people run multiple motors, just not sure how they're wired, and if i need some sort of isolator/switch. any precautions:confused:
 

tx1961whaler

Vice Admiral
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May 31, 2008
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5,197
Re: 2 outboards, 1 battery

Yes, if both motors have a charging system then they need to be isolated from one another. You can use a Wal-Mart lawn tractor battery for the 15 hp and it will work fine.
 

coolbri70

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Oct 6, 2011
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Re: 2 outboards, 1 battery

Thanks, i was suspecting but wasn't sure. I tried to search for info, and kept getting threads about multiple batteries. Now to decide on a switch or 2nd battery:confused: the switch would be lighter, but a backup battery could also have advantage:D
 

Auger01

Petty Officer 1st Class
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Aug 15, 2009
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201
Re: 2 outboards, 1 battery


What he said.

If for some strange reason, you wanted to run both at the same time, then you would need to do something different.

The 15hp has a pull start does it not? That would be all the backup I myself would think necessary. I dont see the benefit of dragging around another 20 pounds of lead in that size boat just to start the kicker.
 

UncleWillie

Captain
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Oct 18, 2011
Messages
3,995
Re: 2 outboards, 1 battery

The simplest solution would be to use a common 1/2 battery switch in reverse.
Normally two batteries are connected to the 1 and 2 and the engine to the common.

Attach the battery to the common and the engines to the 1 and 2 terminals.
That way while you are trolling for hours with the on-board electronics connected to the battery;
The kicker motor would keep the battery charged to assure a restart of the main engine.
 

coolbri70

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Oct 6, 2011
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Re: 2 outboards, 1 battery

I think the switch is the way i will go, i will connect the fuse box for acessories pre-switch, so they have power all the time, regarless of which motor is running. i wonder if my tach would work:confused: i could put it on a switch too, would i have to change the setting:confused:
 

Silvertip

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Sep 22, 2003
Messages
28,771
Re: 2 outboards, 1 battery

You need a separate tach signal from each engine to have a single tach work for both engines. That signal would also need to be switched separately from the battery switch. But why bother with that for the 15 HP. You are trolling. The tach will work for the big motor with no changes since it is already wired to that motor. The fuse box does not need to be changed either. It is already wired to the battery and the instruments get power through the engine ignition switch. Just connect the red battery cable from each engine to BAT 1 and BAT 2 terminals. Connect battery POS to the COM terminal and go boating. You will NEVER use the BOTH position on the switch and OFF will serve no useful purpose other than disconnecting the engines electrics. The boat side of the system will remain hot.
 

coolbri70

Lieutenant Commander
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Oct 6, 2011
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1,554
Re: 2 outboards, 1 battery

yeah, the tach was just an idea, too much hassle, besides i doubt the 15 is gonna over rev pushing my boat unless i reprop it. now thats something to think about, but thats more of a question for the guys in the props forum:D
 
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