Borderline red

[ctmv20]

I had a 1988 135hp merc with a similar rectifier setup and no voltage regulator and the voltage would run up as high as 16V. I was worried that it would mess with the electronics but it never did. Researched it at the time and found out that it is normal for those years with no regulator. For fun I retrofitted a voltage regulator from a later model by following some internet instruction and it kept the voltage around 14V. You should be fine leaving it as is.

[steplift20]

Mine goes to about 15.4 volts. I thought I changed the regulator years ago that fixed the problem but now the regulator that I see is a black box with a bunch of wires coming out of it.the one I installed is a silver box mounted on top of the block with only two nuts that connect the two wires.

[phatdaddy]

Steplift20 s photo

[steplift20]

What is that silver box on top
Phatdaddy was kind enough to post my picture and hopefully someone will check it out. I feel5hat I replaced it (before,voltage regulator ) but 5h3 ones I see now are a different design.

[phatdaddy]

Can u look up the model number on a Mercury parts site and see what the description of the part says

[steplift20]

I have the repair Manuel and can***8217;t find it. And I looked. I will look again. But I think I replaced it before when I was having a problem with my charging. But I can***8217;t find one like that.
The. Ones that I see all have wires coming out of it,the one I have has two nuts where you attach two wires

[spareparts]

Small silver box is rectifier used on low Amp charging systems, large box with multiple wires is a regulator used with the bigger charging systems. Of you wanted to up grade from the smaller system, it takes a different flywheel, stator, and regulator along with the wiring