High voltage over 3500 rpms

Carl · #1 03-12-2009, 09:46 AM

A problem I experienced last season -

When running around 3500 rpms or higher, my garmin fishfinder (160 red) would flash a message stating the voltage was too high and within a few seconds would shut itself off. It is the only electroninc equipment I have onboard so I don't have anything else to compare it to. My volt meter would be reading around 18 volts in these situations. Is this a problem? If so, how do I diagnose and fix it. It's almost warm enough here to start working on the boat. I have a 1988 Mercury / Mariner 150.

Thanks for the help

nymack66 · #2 03-12-2009, 10:45 AM

I will start with the Manuals for the engine, 18V is a clear indication of a bad regulator..

Airslot · #3 03-12-2009, 11:57 AM

No regulator, but good chance of a bad rectifier if I recall. The only parts of that charging system are the rectifier, stator, and battery.

nymack66 · #4 03-12-2009, 12:22 PM

Quote:

Originally Posted by Airslot

No regulator, but good chance of a bad rectifier if I recall. The only parts of that charging system are the rectifier, stator, and battery.

You are correct, my bad

tsubaki · #5 03-12-2009, 01:56 PM

We had the same problem on a 75hp Mariner.
Ended up being the voltage regulator.

THEFERMANATOR · #6 03-12-2009, 06:53 PM

Take a picture of the powerhead so we can see what charging system you have. I believe that in 88 it could be a 9 or 16 amp system. The 9 amp was unregulated and would charge REALLY high once the batteries got charged. The 16 amp system has a regulator on it for most years.

turbinedoctor · #7 03-12-2009, 07:58 PM

I experience the high voltage also but I dont lose any electroincs. Mine goes up to 16 volts when fully charged and there is no regulator.

My question is, is it possible to install a regulator, or has anybody installed one on this type of charging system. If so what kind of results did you get.

THEFERMANATOR · #8 03-12-2009, 08:11 PM

It's possible to add a regulator, but it is easier to run 2 batteries and turn on a couple of lights to keep the charge down.

turbinedoctor · #9 03-12-2009, 08:20 PM

Quote:

Originally Posted by THEFERMANATOR

It's possible to add a regulator, but it is easier to run 2 batteries and turn on a couple of lights to keep the charge down.

Maybe I can talk my wife into a 200watt stereo system for the boat by telling her it is to keep the batteries from over charging.

turbinedoctor · #10 03-12-2009, 08:23 PM

I just dropped a line to CDI tech support to see what they have to say about a regulator for this type charging system. I'll let you know what they say.

Probably " turn on some lights and install a second battery"