# Electric start outboard constant power or battery cut of switch?



## Shallows (Mar 29, 2020)

I bought a boat with a 2015 Yamaha 15hp electric start tiller motor - they had the Yamaha factory starter/alternator power wires going directly to the battery, so basically the outboard had constant power - even when sitting for long periods; is this correct?

Or, should I buy a battery disconnect switch so I can cut off the Yamaha's power to the battery when the boat is sitting on the trailer.


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## firecat1981 (Nov 27, 2007)

It doesn't get constant power as there is no draw or feed when it's not running. It only draws power when you push the starter button, and can only supply power when the motor is running. I had mine hooked up direct for a decade with no issues.


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## MariettaMike (Jun 14, 2012)

Shallows said:


> I bought a boat with a 2015 Yamaha 15hp electric start tiller motor - they had the Yamaha factory starter/alternator power wires going directly to the battery, so basically the outboard had constant power - even when sitting for long periods; is this correct?
> 
> Or, should I buy a battery disconnect switch so I can cut off the Yamaha's power to the battery when the boat is sitting on the trailer.


Battery switches serve as a child proofing device for not starting the motor accidentally, blowing the horn, leaving the nav lights on, running live well pump dry, .....

We all can act childish sometimes.


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## lemaymiami (Feb 9, 2007)

Amen... until you turn that ignition on there's no power to your motor - the ignition switch provides that function... As for a battery cut-off switch once you get past a very simple installation (small outboard with little in the way of additional power needs..) then I always want a battery switch installed as part of the rigging process - particularly when you go to a two battery system...


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## Shallows (Mar 29, 2020)

firecat1981 said:


> It doesn't get constant power as there is no draw or feed when it's not running. It only draws power when you push the starter button, and can only supply power when the motor is running. I had mine hooked up direct for a decade with no issues.


Okay thanks, good to know. My main concern was that it doesn't burn up the ignition system like I had always heard it would in a car (if true) such as if you left the key in on/run mode - but hopefully outboards are wired to deal with this better!


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## Shallows (Mar 29, 2020)

MariettaMike said:


> Battery switches serve as a child proofing device for not starting the motor accidentally, blowing the horn, leaving the nav lights on, running live well pump dry, .....


Understood; I actually have a switch panel for all the accessories - its just the outboard that was wired direct.


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## Shallows (Mar 29, 2020)

lemaymiami said:


> Amen... until you turn that ignition on there's no power to your motor - the ignition switch provides that function... As for a battery cut-off switch once you get past a very simple installation (small outboard with little in the way of additional power needs..) then I always want a battery switch installed as part of the rigging process - particularly when you go to a two battery system...


Okay thanks, I actually have a two battery system - but tempted to eliminate the trolling motor to cut down on weight. 

I did find a pretty simple Perko single function battery disconnect switch (Perko 9621) that is very compact, so I could install that.

But generally if you had a small tiller outboard wired direct to a single battery and it was sitting on its trailer for a few weeks - would you just leave it hooked up, or manually un-bolt the battery wire?


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## firecat1981 (Nov 27, 2007)

Leave it hooked up. It won't hurt anything as it's a simple circuit system. Without your finger on the starter switch no power is flowing.


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## Shallows (Mar 29, 2020)

firecat1981 said:


> Leave it hooked up. It won't hurt anything as it's a simple circuit system. Without your finger on the starter switch no power is flowing.


Okay, good to hear; I may do that as I like the idea of keeping things simple, main concern was just that I wasn't damaging its ignition or something.


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## Vertigo (Jun 3, 2012)

A battery switch is to protect the battery, not the motor. If you have lights, instruments, pumps, etc. a battery switch ensures that they won't drain the battery if they are left on or if there are weak grounds in the system.


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## lemaymiami (Feb 9, 2007)

More importantly with a two battery setup and a battery switch you can isolate battery #2 so that it isn't getting used at all until you run down battery #1 and need a boost to get started again... Turn that switch so that both batts are combined and fire that motor up - then switch back to battery #1 only and while running re-charge it... Every now and then set your switch on battery #2 and run it there for a day or so to keep everything working properly... You'll be glad you did. Make a point though of never running with both batts on line and you'll always have the reserve power needed if the battery you're using gets discharged and is too weak to start your motor....

Folks like me that are on the water day in and day out won't be found without a two battery setup... and that's how I'd rig any skiff that I'm working out of....


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## Shallows (Mar 29, 2020)

Vertigo said:


> A battery switch is to protect the battery, not the motor. If you have lights, instruments, pumps, etc. a battery switch ensures that they won't drain the battery if they are left on or if there are weak grounds in the system.


This got me to thinking, since I am storing the boat in the garage maybe I should install a disconnect to just prevent the possibility of any shorts in any of the accessories that could cause a fire when sitting - however remote the possibility.


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## lemaymiami (Feb 9, 2007)

That's just one more reason to have a standard battery switch (whether you have only one batt - or multiple batts, turn the switch to off and you've disconnected your entire power system, not a bad idea for long term storage.
Just make sure to install it where it's easy to reach (another of those "ask me how I kwow" propositions...).


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## State fish rob (Jan 25, 2017)

I just disconnect positive side of battery on skiff when I put it up 
Wing nut


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## Gatorgrizz27 (Apr 4, 2015)

I put a simple on/off battery switch on mine. I’ve has starter solenoids stick on motorcycles before and the starting motor will run continually until the battery dies. Can heat the wiring up pretty quick. Mines also hidden so it serves as an anti theft device if left at the dock. 

Otherwise, there’s no real drain to speak of.


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