1999 15hp Johnson - want to install alternator

Hi all,

Ive got a 1999 15hp Johnson pull start. Is there anyway I can change the flywheel / or what ever it may be, to make this motor output voltage so I can charge a small 12v batter for fish finder, lights etc?

Much appreciated

You would need to find a NOS stator and add a rectifier..but output is only about 4amps at WOT so lights may draw out more than puttting in.

I don't know that motor or whether it ever came with a stator. It's much easier to simply buy a battery that's big enough to handle those loads for the length of time you need to run them. If you have LED lights the loads are almost nothing so it makes sense to switch all lighting to LED. As for fish finder, see what the draw is in watts. Use Ohm's law to calculate amps and multiply that by the number of hours you want to use it between charges. That will give you amp-hours. Buy a battery with at least twice or thee times the reserve capacity.

Thanks for the quick reply. I was thinking it may be a better option to just use a car battery for the day and then take out to charge externally. LED lights would be getting used all round.

Was just curious of the 1999 15hp Johnson came with the stator or not...

Great forum guys, Thank you from Australia