Volt guage fluctuation.

[dwb1957]

If a volt guage fluctuates or jumps between 15 & 12v while under power, would you suspect the alternator first or connections\guage.

With a Volt meter, check @ alternator first? Any advice?

2003 21i Limited w\ 125 hours. w\ 2 batteries (one for boat & one dedicated for stereo system), Stinger Isolator. Also have ProSport 12
charger @ slip.

[Tanner]

My first question would be.... how big is your stereo system and what's the size of your alternator?

[dwb1957]

The alternator is the 65 amp stock one...

The stereo is a Sony mp3 deck w\ 4 MB Quarts fed through a Hifonics zx6400 4 channel Amp + a 10" Clarion Subwoofer fed by another Hifonics amp.

Doesn't matter though, the voltage jumps are not affected by stereo rockin' or off.

My question is "would the guage do this if an alternator was croakin?" or would it be more likely a connection...

The Isolator is rated @ 80amps, but still not affected by stereo operation.

[lee]

Look for a loose wire on the alternator. Sometimes they will vibrate loose.

[gman]

Look for loose wires on the gauge. I had this problem on a brand new boat. Voltage was steady and then moved from 10 volts to 15 volts and back down and inbetween. Once wires were tightened down, problem went away.