1996 Merc 150 intermittently pegs volt meter at 17 volts.

[bobdec]

Engine is a 1996 150 Mercury , 2 stroke, 150 HP . 40 amp 2-regulator charging system. Dual batteries via Perko switch , problem shows running on either starting battery #1 or deep cell battery #2.
Done a lot of searching but have not found any thing on an over voltage condition. I am guessing one of my two voltage regulators is hanging up at full charge when the problem occurs. It will happen 1 to 3 outings initial startup (cold condition) and will also pop up when just cruising at 4000 RPM (warmed up condition) . Comes and goes w/o any rhyme or reason. Volt meter goes from 13.5v normal an pegs, electronic fishing display beeps with a high voltage of 17.5 volts indication. Then after a variable amount of time 5-20 mins the voltage goes back to normal. Been living with this for all last season, but would like to get it resolved to save my electronics. Can I just remove the red wires on one regulator at a time and run w/20 amp charging for a week or so to isolate to a regulator, or could this be a wiring problem ?. If it is one regulator can it be replaced alone or should I do both ?

 

[Faztbullet]

If you have every switched between batterys while engine was running it possible both VR's are damaged....amazon is your friend.

 

[ondarvr]

While running you should see around 14.2 volts, 13.5 would be low and possibly indicate a problem.

 

[bobdec]

Fatzbullet, 10 never switched batteries going through 'off' , I have switched them going through the 'both' position. Have to look up the specs on the switch, but I thought the physical movement of going '#1- to both- to #2 position, or reverse procedure' swept the contacts and always kept 12v from the batteries connected to engine.

ondarvr, I'll verify voltage, prior to replacing the regs, since my voltage gauge is 21 years old it may not be that accurate, I have the gauge rotated so needle is straight up at 12V and I usually when running I just scan the panel and insure needle is 1/2 inch to the right of center. Never paid much attention as long as it's charging. When it fails the needle pegs at the right needle stop. My fish finder/dept gauge pops up an over voltage window indicating 17.3 volts.

Decided I'm I going to throw in both regs .. boat is rack stored, and I will drag it home for spring commissioning, it's a PITA the put on marina service rack to get at the voltage regs during the season. So I like to do everything at one time at home with my tools available. I noticed the regulatorss come in three flavors 1- the lower cost no-name 6 wire units, Sierra 5 wire, and CDI / Mercury 5 wire at the top end. I usually do not go cheap on marine parts, but I also don't throw money away, I would assume the $35 ones are not as reliable long term. I trust Sierra, CDI and will probably go with them. Any thoughts ?

 

[Faztbullet]

I have some $35 ones on their 4th year on son-in--law motor,,,,,,,