Yep. Dont trust a gauge. Check it out with multi meter. And check without any accessories on and then with all on and lights too.

At the battery before starting engine. 12.5 after starting and raving her up the volts climbed to 15.4. On my multimeter Same as the gauge

Sounds normal.

Phatdaddy, 12.5 volts then when the rpm’s go up it increases to 15.4 volts. That’s normal?

Agree with Pipe, seems ok. Now that you ve confirmed your dash gauge,keep an eye on it.

Asking this because i don t know, is there a stand alone voltage regulator on that motor? I never really understood the voodoo magic of the whole stator switch boxes electronics of that motor

From what I understand is the the voltage regulator keeps the voltage at a certain level thats good enough to charge the battery but not high to cook the battery
But from what Im seeing and hearing ,15.4 volts is normal I called wagners marina and talked to a mechanic and he said its good. If the voltage regulator was bad it would just go to red. I dont know. maybe I should not look at the gauge. But I like everything to work right .

two types of charging systems on old style Mercs, one had a rectifier, one has a regulator. They are pretty basic, the rectifier is used on the low amp type, its basically runs wide open, it doesn't produce enough amperage to screw anything up, but makes a lot of voltage and output is directly related to rpm. The regulator type is similar, but operates in an on/off type situation, you'll see high charging rates, then no charging till the voltage gets in the 12 volt range, then high charging. So to answer your question, sounds like its operating normal. My johnrude does the same thing, it will scare you when you're offshore and look down to notice the voltage around 12 volts idling, you rev it up and it will come up.

Spareparts,first good to see your back and if you say it’s normal then that’s good enough for me.

Update, two issues I was concerned with.
1st. Voltage, seems to go up to 15 volts when running 5he engine, the voltage creeps up to that 25 but was told that***8217;s normal. Ok so it***8217;s normal
2 nd. Gas was leaking from the bottom carb when tilted up a little when not running. I have three carbs that are mounted sideways and was also told that happens. They don***8217;t leak when running and I shot some carb cleaner 5hat the three carbs and I didn***8217;t see any gas leaking. So my motor is happy again. Next I hav3 to catch a dam keeper. Fluke.
Just giving an update in case anyone. Wants to know.
P.S. I love my 2 stroke. 150 mercury blackmax
Question, why do numbers appear when I put down a sentence? Like. ***8717 why?

high voltage
 

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.