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Cory

Alternator voltage?

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Cory

When idling my battery voltage is 14V. As soon as I put it in gear, voltage drops to 13.3V. At higher rpms the voltage is still around 13.3V to 13.5V. Is this normal? Why is the voltage lower at higher rpms, but 14V in neutral?

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REW

Interesting, Your voltage should be 14-14.5 at all RPM. The possible exception is under heavy load at idle, the alternator may not be able to keep up. There is some circuitry on the alternator that is supposed to keep the voltage flat. First thing you need to do is use a meter to check the alternator at the alternator connections. Do this under various loads and step up the RPMs. This will let you know if you have a gauge acting up or if the alternator is acting up (voltage regulator).

Also just for fun check the connections on the alternator while you are there.

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MadMan

When idling my battery voltage is 14V. As soon as I put it in gear, voltage drops to 13.3V. At higher rpms the voltage is still around 13.3V to 13.5V. Is this normal? Why is the voltage lower at higher rpms, but 14V in neutral?

I had this same problem in my car, turned out to be the alternator.

It really baffled me for quite a while since in all my past alternator problems the alternator would start keeping up at higher rpm. The only expiation I came up with is that voltage regulators have gotten smarter and limit the charge output at higher rpm.

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Cory

We are on vacation, but the maintenance manager loaned me his volt meter and battery load tester. The batteries are fully charged 12.8V after resting for a while, the alternator is delivering 14.4V to the battery, and a battery load tester said the batteries are fine.

The volt gauge on the dash is wandering a lot and is clearly not accurate. So, something is not right with it. Not sure what to do next. Could be a loose or corroded connection, or a faulty volt meter in the boat. I don't know where those connections would be.

We are on vacation until Wednesday. I'll probably call the dealer on Monday for advice. Any thought? What precautions should I take?

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MadMan

Do you have one battery, or an isolator with multiple batteries?

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Cory

Two batteries and isolator switch

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shawndoggy

you could check to make sure all of the ground and power connections are tight at the batteries and the breaker.

If they are, my guess would be a loose connection in one of the factory distro blocks under the dash (power or ground).

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Cory

My dash is flickering back and forth from night mode to day mode. Battery voltage says 10.1V on dash, but volt meter direct on battery says 12.2v. Volt reading on dash is all over the place. NAV light flickers. Definitely have a loose or corroded connection somewhere.

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Cory

I can find the ground bus bar, but don't know where power bus bar is located.

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OLDGUY

The positive bus on the old boats is under the throttle. It's where the breakers are located.

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shawndoggy

yeah like oldguy said, the power distro is the breaker bar setup. takes like six screws to remove from the throttle panel and coax it out a bit to see the connections.

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Cory

Ok. I know about those breakers, didn't realize that it was the main positive power bar though. Thanks for the feedback.

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Cory

My electrical problem finally caused my boat to turn off and the dash to reboot. Fortunately, AWS saved the day. 15 mins on the phone with their lead tech and the problem was diagnosed and resolved. Turns out one of the electrical connections on the backside of my pwr switch or start/stop switch was loose. When I get home, I'm gonna pull those connections off one at a time, squeeze them with pliers and push them back on their respective terminals.

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Cory

AWS rocks! I really thought our boating vaca had ended early.

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REW

WOW

Gotta love those computer driven boats.

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Cory

So, I pulled the suspected culprit connection off the terminal on the backside of my power switch, lightly squeezed it with pliers and slid it back on. My voltage reading on my dash went from 13.8V or 13.9V when the engine is running to 14.2V. My batteries read 14.4V at the battery when read with an independent volt meter. Tightening up this one connection was a big improvement on the dash volt reading. The connection is no longer intermittent.

Ironic how such a simple electrical problem can wreak such havoc.

Edited by Cory

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