Battery size for my 20hp Johnson electric add on

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newyota
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Joined: 12 May 2016, 00:55
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Battery size for my 20hp Johnson electric add on

Post by newyota »

I am making slow progress in putting in my electric start.Finally got my stator and rectifier on,starter-solenoid and bracket assy needs on along with switches and Decideing what battery to use and want to save space and weight.I saw where someone actually used a lawn/garden battery to start his motor..I also was checking out a jet ski or motorcycle battery.I am only using it to start motor on my 14’ Jon at this point since everything else has been on my deep cycle for a long time.

MrGiggles
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Joined: 12 Jul 2017, 21:42
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Location: Springfield, MO

Battery size for my 20hp Johnson electric add on

Post by MrGiggles »

If you're only using it to crank the motor, I'd just run over to Walmart and grab one of the $29 lawn mower batteries. Should work fine.

newyota
Posts: 97
Joined: 12 May 2016, 00:55
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Battery size for my 20hp Johnson electric add on

Post by newyota »

Thanks.

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wmk0002
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Location: North Alabama

Battery size for my 20hp Johnson electric add on

Post by wmk0002 »

I use a U1 lawnmower battery for my Yamaha F25. Also previously used it on a 30hp Yamaha 2 stroke. No issues for either one.

I assume you also have backup pull start since its a conversion, so even more reason to go small as possible.
2016 Alumacraft 1648 NCS - 2020 Yamaha 25 HP Tiller - 1992 Johnson 9.9 HP Tiller
https://www.tinboats.net/forum/viewtopi ... 21&t=40764

newyota
Posts: 97
Joined: 12 May 2016, 00:55
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Battery size for my 20hp Johnson electric add on

Post by newyota »

Yes have rope start also.Just got done with conversion and took my battery off of riding Mower and it crank no problem.Charging circuit seemed to be working as I did see increase in voltage while increasing rpm.Was on muffs so couldn’t take it too high.I was concerned about the starter since bench tested only the gear popped out but right back in.Guess they have to be engaged to stay up.Was not sure about that since I had another used one doing the same thing.Only other concern was the timing stopper for the high end. Bracket I used was from a 35hp (34*)so the screw was not adjusted for my motor(30*).Made some measurements and put it at full throttle and locked the stator plate in position best I could and took old bracket off and put new starter and bracket on and it was off so adjusted and thought about doing the Joe Reeves Timing method which can be done out of water to see if it is ok?Just need to get it on the water and hopefully that is the last step and engine doesn’t blow..thanks for the input on battery.

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wmk0002
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Joined: 17 Apr 2014, 15:39
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Location: North Alabama

Battery size for my 20hp Johnson electric add on

Post by wmk0002 »

newyota wrote: 30 Aug 2021, 15:55 Yes have rope start also.Just got done with conversion and took my battery off of riding Mower and it crank no problem.Charging circuit seemed to be working as I did see increase in voltage while increasing rpm.Was on muffs so couldn’t take it too high.I was concerned about the starter since bench tested only the gear popped out but right back in.Guess they have to be engaged to stay up.Was not sure about that since I had another used one doing the same thing.Only other concern was the timing stopper for the high end. Bracket I used was from a 35hp (34*)so the screw was not adjusted for my motor(30*).Made some measurements and put it at full throttle and locked the stator plate in position best I could and took old bracket off and put new starter and bracket on and it was off so adjusted and thought about doing the Joe Reeves Timing method which can be done out of water to see if it is ok?Just need to get it on the water and hopefully that is the last step and engine doesn’t blow..thanks for the input on battery.
Nice. So can that specific model be converted to a 35 hp?
2016 Alumacraft 1648 NCS - 2020 Yamaha 25 HP Tiller - 1992 Johnson 9.9 HP Tiller
https://www.tinboats.net/forum/viewtopi ... 21&t=40764

newyota
Posts: 97
Joined: 12 May 2016, 00:55
5

Battery size for my 20hp Johnson electric add on

Post by newyota »

wmk0002 wrote: 31 Aug 2021, 11:54
newyota wrote: 30 Aug 2021, 15:55 Yes have rope start also.Just got done with conversion and took my battery off of riding Mower and it crank no problem.Charging circuit seemed to be working as I did see increase in voltage while increasing rpm.Was on muffs so couldn’t take it too high.I was concerned about the starter since bench tested only the gear popped out but right back in.Guess they have to be engaged to stay up.Was not sure about that since I had another used one doing the same thing.Only other concern was the timing stopper for the high end. Bracket I used was from a 35hp (34*)so the screw was not adjusted for my motor(30*).Made some measurements and put it at full throttle and locked the stator plate in position best I could and took old bracket off and put new starter and bracket on and it was off so adjusted and thought about doing the Joe Reeves Timing method which can be done out of water to see if it is ok?Just need to get it on the water and hopefully that is the last step and engine doesn’t blow..thanks for the input on battery.
Nice. So can that specific model be converted to a 35 hp?
Yes..You can put a 35hp carb and intake on it from what I understand.Actually sold the carb and intake and lower unit from the 1977 35hp parts motor I bought for electric parts to a kid that wanted to convert his 25hp to 35hp.Got my money back👍