Electric Start?

I have a 1984 Johnson 35 HP outboard on a 16 foot Klamath center console I want to use for crabbing and hunting.
I am 62 years old and was thinking about going to electric Start.
I found a starter solenoid and starter motor online for a reasonable amount but don't know about other brackets or other hardware that would be needed?
Also the engine currently has a flywheel on it but is a pull start motor.
Do I need a different flywheel for electric Start?
Wiring I can handle and the boat already has a battery for the marine radio and fish finder.
Do I need a second separate battery? An alternator to charge the battery?
Is this a good idea?
It starts now without a lot of effort.

Has anyone tried this?
How does a starter work without a flywheel?
I am automotive by nature so go easy on me.

Does the kit come with any directions?
This is an interesting idea.

The starter needs a flywheel to engage.

If it was me, I wold want an alternator on the setup.

I use a small Group 24 battery for cranking and a separate 100Ah LiFePO4 battery for trolling motor and accessories.

My tinnie had a 30HP Johnson when I bought it. The Johnson only had pull start. For a number of reasons, I wanted to add electric start. I do have some limited automotive capability but no outboard experience. I looked for a donor motor, but there was little available to me in my region. I looked for kits that might help with the conversion. I was not comfortable that I really understood all that I needed, and so I never pulled the trigger on buying parts. From what I could tell, that conversion was going to cost me at least $800 unless I could find a smoking deal on a donor motor somehwere. Meanwhile, one fishing season had slipped by, and another might, too.

I ended up just selling the finicky outboard and buying a new 20HP Merc. My hobby is fishing and not fixing old outboards. I can do a lot of my own maintenance, and I'm happy to do some of that, but there was a limit to the amount of time and expense I was willing to sink into that old motor.

I was contemplating the same thing. I figured a fully charged battery would be able to provide starting all day.
I found that my motor already had the charge coil under the flywheel, so I would only need a regulator/rectifier. Some electric starter kits come with a ring gear, or a flywheel with the gear attached. Mine was on a 2016 Yamaha 30 HP. 2 stroke.

The parts were cheaper than I thought when I converted mine. I think it was something like $120 total, but that was way before covid. No idea what current pricing is.

I was happy with mine and never had to charge my battery again. Lights, fish finder/GPS and maybe a few other small things.

Just my experience. I doubt I would do it for $800. I think I bought my whole motor with electric start already in it for something like $400

The starter and solenoid are under $100 and the flywheel currently on the motor has teeth.

No alternator.

No problem.

Prior owner did the electric-start "conversion". Everything fits, and it works.

This old body will buy a new battery every year or so if needed. Better than trying to pull start.

Back in my much younger days, I had a 30hp Johnson with electric start but no charge system. The old motor did start good, but only charged the battery a couple times thru the summer even running lights at night...should be fine with a good battery.

This boat currently has a ion battery in it for the marine radio and fish finder and has a battery charger installed as well. I can plug it in at night and just let it charge

I'm no expert in this, but........ I know most LifePO4 batteries are not starting batteries. We're seeing more of them advertised as starting batteries. Couldn't the deep cycle LifePO4 battery be used as a starting battery in an emergency? This is assuming you want an alternator for the occassions when you can't charge your starting battery. I may be offbase on this suggestion.

I have an 84 Johnson 35hp that was originally only recoil start.
I simply took the starter, solenoid, and bracket off of a junk motor I found and bolted them onto mine.
I run a group 24 battery for the starter and a Li Ion jumper pack for my fish finder and GPS. I simply plug both in at the end of the day, since its got a recoil start I've never worried about it charging the battery as these motors just don't put that big of a load on the battery. Its not like cranking up an old V8, ts a twin cylinder two stroke with a starter not much bigger than what's found on most lawnmowers. A lot of guys I know only run a small AGM UL1 sized battery.

A motor that came with electric start came with an alternator coil under the flywheel, and a remote enrichment device or electric choke solenoid too.

I have those parts for mine but when I added the starter years ago I did it in a hurry fully intending to add the rest later but never did. I'd venture to guess the battery would start that motor for days, maybe even all week if needed without a charge. It starts easy, I bump the starter and its running. Because it didn't charge, I run the LED nav lights, GPS, and fish finder off a Hf Jumper pack I bought for $50 about 6 years ago on sale. Its never gone dead, and if it did, I could always just switch over to the starting battery. If the starting battery dies I'll likely buy a small AGM to replace it with. I plug the boat in every night either way though. Loosing the 60lbs by going with a smaller battery will mean more to me than spending a Saturday swapping over the stator and regulator and wiring in a regular ignition switch. Right now I just put a starter button on the battery box under the left seat that I can hit with my foot I was going to put it right on the motor but figured if I change motors I'd have to rewire another motor.

I have a 50AH LiFeP04 battery in my boat. I had battery problems when on the water, and used it to start my 70 HP Johnson. I didn't think it would work, but it did.

Since that day, I have used my 100AH batteries to start various motors to demonstrate them. They worked on all but a 225 Evinrude that had been sitting for a long time. Even a Group 29 lead acid starting battery had a hard time with that one. Had to hook up TWO starting batteries to get it going.

Do as you see fit, but if your lithium starts it easily, I wouldn't worry about it. A trolling motor is a large electric motor, similar to a starter.

The starter and solenoid are less than $100 - you might want to price out the solenoid and rectifier. They were surprisingly cheap when I bought mine.

With or without charging, I think you will be okay.

Oilsmoke
I appreciate your response because I currently have a supercharged 496 big block Chevy in my truck with a magneto on it and no charging system at all. Yet!!!
The motor will start for well over a week and run until I can't afford the 116 octane fuel anymore with a $99 interstate battery from Costco.

AlanT said:

I'm no expert in this, but........ I know most LifePO4 batteries are not starting batteries. We're seeing more of them advertised as starting batteries. Couldn't the deep cycle LifePO4 battery be used as a starting battery in an emergency? This is assuming you want an alternator for the occassions when you can't charge your starting battery. I may be offbase on this suggestion.

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Definitely. I have used my 50ah lithiums to crank up the outboard before. I didn't think it would work since they only have a 40 amp max discharge, but they didn't seem to care, fired right up.

The issue there is that the BMS in a standard lipo battery is not optimized for the charging system on an outboard, it can increase, decrease, or completely shut off the charge current going into the battery as it sees fit, which can be pretty hard on the outboard's charging system.

MrGiggles said:

Definitely. I have used my 50ah lithiums to crank up the outboard before. I didn't think it would work since they only have a 40 amp max discharge, but they didn't seem to care, fired right up.

The issue there is that the BMS in a standard lipo battery is not optimized for the charging system on an outboard, it can increase, decrease, or completely shut off the charge current going into the battery as it sees fit, which can be pretty hard on the outboard's charging system.

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That is a very good point.

If you do put in a charging system, it would probably be best if you use a regular battery and save the lithium for the trolling motor.

In my little black boat where I added a charging system, I started out with a small battery, maybe a lawnmower battery. It worked great, but I got tired of having to charge the trolling motor battery, so I ran wires forward and deleted the small battery. It was perfect! I never needed to charge again, and I never ran out of juice.

I generally ran a couple of miles to and from where I fished, and the little 6A (I think) system took care of business. I checked it a couple of times after fishing, and it would read 12.7 or 12.8V. Eventually, I trusted it. After that I just went fishing and never thought about it. I was very happy with adding a charging system!

I found all original factory new starter $201 and factory new solenoid for $57 so I think I will go that route.
Anyone know where I can find a bracket? I have access to a lathe and mill if it's not to complex to make?

Is this the correct flywheel or do I need something else/different?