Charging problem

I have a 1989 Johnson 88SP, that is charging at about 17 volts. I’ve checked the stator and it reads about 1 ohm. I replaced the rectifier, but still the same. After engine start, it will charge at 14 volts, but within a few minutes at idle it is at 17. My depth finder shuts down due to high voltage. Any help greatly appreciated, trying to get ready for Canada trip. I saw a note on one of the parts websites that said not to use their rectifier with a maintenance free battery or it will over charge. Makes no sense to me, all you can buy are maintenance free batts.

The odds are good that it is the Voltage regulator/rectifier.
Very untrue that all you can buy is Maint. free batteries. All I will buy is Maintainable.
I leave my 2 Minnkota chargers plugged in 24/7. I need to add quite a bit of water to all 3 batteries TWICE a year (about a liter each). I have 4 years on theses batteries going into year 5. The way I look at it is that I would never want to buy a maintenance free battery. You should check all water levels on a regular basis.
But none the less Try the O.E.M. VR/R.

All my boat batts are maintainable. I add water 1-2 times per year.

Sounds like a bad voltage regulartor to me.

Now things get a little confusing to me. I did a quick lookup on the schematic for the 1988 OMC 88 HP.

They list P# 582399 — RECTIFIER & LEAD ASSY.. 88 MODELS

What I don’t understand is is this a combined rectifier/voltage regulator?

Because…

They also list:

583529 — RECTIFIER & REGULATOR ASSY.. 90/110 MODELS

So you replaced the rectifier? But the fact that the 90/110 HP models have a combined rect/regulator leads me to believe that there may be a seperate voltage regulator in the 88 somewhere?

I’m not seeing it listed on the parts list, so what I’d want to find out is where is the voltage reg on that motor? I wonder if the voltage regulator is part of some other system on the 88?

Grouse