I did the same to my 1979 35hp. I left the original ignition and and skipped adding the stator to charge the battery. I bought a $39 jumper pack from Harbor Freight, a generic automotive bump starter switch, (looks similar to the original kill button) some wire and two battery cables to a jump starter plug from a tow truck which I added the other half to the jump starter so I wasn't dealing with live spring clamps in an aluminum boat.
The jumper pack will start the boat as many times as needed all day long. Plus now I bought a Li-Ion pack as well that does even better but either option eliminates the need to carry a 50 lb deep cycle or starting battery that wouldn't likely be getting charged property anyway even if it had an alternator circuit.
Most outboards only charge around 10 or 12 amps at best and the nature of how miost of us use these motors isn't likely going to replenish the battery in any significant way,
For me, once the boat is in the water I travel maybe a 5 or 6 miles out, much of which is idle time through no wake zones where the alternator is barely putting out anything, then over the course of the day fishing its a series of starts and stops as we move around chasing fish. Then the ride home, often with the lights and spot lights burning so the alternator does little on the ride home as the spot light takes far more from the batteries than the alternator can ever put back in that short distance. I did upgrade to all LED lights so that helps but more than once I forgot to charge the jump pack on a Sat night and went back out on Sunday and it still had plenty of power for the second day.
My parts list included:
- New starter off eBay for $50
- Used starter bracket from ebay $32
- Battery cables (Harbor freight jumper cables) $34 2ga 20ft set on sale that I cut four feet of cable off of and ended up with 16ft jumper cables and two battery cables.
- Summit bump starter switch $8
- Misc wire. heat shrink tubing, and wire ends maybe $5 or so tops.
- Starter relay from junk motor at marina $5
That all was about 9 years ago or so.
Over the years I did pick up a parts motor with electric start which can donate the stator if needed but as long as the original ignition is working I see no need to make the change.
At this point I"d be more likely to just buy and carry another Li-Ion power bank if I thought I needed more battery power but for a 16ft alumunum boat what I have works fine,
