I have a 1988 mercury 200 hp that runs perfect. However when I check the voltage shown on my lowrance 332 locator it reads 18+ volts when running at cruise speed 3000+. I can bring the shown voltage down to 13 by turning on pumps, jackplate or tilt motor. While idleing the voltage shows 13 volts. It has been doing this for a considerable time and I even had the stator replaced but no change. I no longer watch the voltage as it just makes me nervous. Is this just a false reading?

sounds a little high but should be alright. 13 is what you want at idle

Voltage rectifier/regulator?

Check regulator. Its about 2 inches square. On top center, right behind tha flywheel between tha heads. Will have two wires that go to tha rectifier.......

That is too much of a charge. You probably need to replace your voltage reg.

Easy to check with volt meter at battery. Word of advice= install a 50amp fuse in the red wire going from the regulator to the starter solenoid.

Thanks for your replies. Can someone tell me what bad things can happen due to this higher voltage. So far no battery or locator problems.

Battery boils the acid out. Tachometer fries along with any other guage that is linked with the engine. Boat wiring like dash lights go out along with any accessory like depth recorders . Bottom line, it's like running 110 lights in your house on 220. It may not sparkle right away, but It will definately be going south......

Thanks again, Gary your advice to install a 50amp fuse in the hot wire is interesting. What is the main purpose of this fuse? I'm not aganist using one just would like to know what pitfall we are avoiding.

50 amp?. Its only a 14 or 16 (don't remember for sure) guage wire. With a 50, tha wire will fry long before tha fuse lets go unless ya get a direct short ta ground. Then it won't mater what size fuse it is. I understand tha reason but feel a 50 is a little to much to protect tha stuff...........jmo

We ran tha 16's (still do on hot rod motors) without a regulator for years with good battery maintance but with all tha new fishin' related electronics that are being used now its almost a must to have tha regulator. Most (newer electronics) will shut down at 16+ volts nowdays from what I'm hearing.......

TRW its the big(bigger than 14) red wire coming out of the regulator that if you have a reg. problem it burns the top of your motor. Has happened many times in the past wipping out the stator. The fuse is determined by the charging amps of the stator 35amps. You do know that an Optimax has a frigging 100 amp fuse on the charge wire? I wondered about that one.

Undersatnd but that motor doesn't have that type regulator/rectifier. Just a "plain jane early model" type that uses two small wires going to tha rectifier. Completly different system than tha one your thinking about......

Its a 16 amp charging system, not tha 40.....

Yeah, and the voltage regulator retails for more than $200. Ouch!

Yes $207 to be exact for the reg from mercury. However I'm getting one from Napa for about $40 so we will see how that works. One thing about this site is you get a lot of good advice and it is appreciated.