Voltage gauge fluctuating

[Majr808]

I've noticed that while the engine is running my voltage will fluctuate between 12-14v. Sometimes it just sits around 12, and then stays at 14 for a while. Stereo & other electronics can be powered off, this has no effect on the change. Is this a sign of an alternator going out, not holding a 14v charge, or is this how they function normally? I know it's normal for this to occur in my vehicle.

[chpthril]

What year boat? Analog or digital readout?

[Majr808]

Analog read out. 2005 22v. Faria gauges

[talltigeguy]

I think those gauges are about as good as your gas gauge. I would confirm with a voltmeter at the batteries before I made any declaration of whether this means anything. IF this is real, then there is an issue. Your boat should be at 14+ volts if batteries are fully charged while engine is running. 12+ at rest.

[lee]

I have seen a loose wire on the back of the alternator cause that problem before.

[cucv]

At say 3000 rpm does the voltage fluctuate?

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[chpthril]

Could be tough, but you are going to want to use a digital volt meter and measure at the alternator when the issue is happening. If the voltage is steady there, then you have to work your way up the stream. Just note though, this issue is not going to be strictly a B+ issue. Can be on the B- side, so the grounds are just as important.

[Majr808]

Thanks guys. I'll volt meter while this is happening to rule out the gauge side. I believe wires are tight on the alternator but I'll double check.

Does a failing alternator go out like this?

[Majr808]

If was a loose wire on the back of the fuel gauge, issue is resolved.