Fluctating Voltage

[Boilers2000]

92 searay with a 4.3 LX engine...in neutral idle voltage at battery jumping from 13.6 to 14.2, in gear idle and higher RPMs sfeady at 14.3 volts. Battery charged at 12.8 volts after shutting off. Feel like it an alternator, but want some input.

Thanks in advance!

 

[Mc Tool]

What are you measuring it with ,and where in the circuit are you measuring it ..... Are you looking at the gauge on the dash or putting a multimeter on the battery terminals ? It does make a difference to diagnosis

 

[Boilers2000]

Sorry, I meant to include that...I'm doing multimeter at the battery for all the readings. I'm going to check all the connections at the alternator tomorrow...I had my canvas collapse during a storm, and water got inside, so I'm hoping it's corresion at the alternator, but don't think I'll get that lucky

 

[muc]

google "preform battery ripple test"

 

[Mc Tool]

Im not up with your motor in particular but some set ups have the regulator sensing voltage from the switched side of the ignition switch , or some place other than the battery + but the alternator delivers its output straight to the battery+ and if there is a poor connection the reg will see a drop in voltage at the sensor wire and up the alt output to compensate.
A volt drop test is a good way to suss this . It could also be a crook earth or even just a dodgy reg . Dont forget to check the zero on your multimeter ohms setting if you want to use the meter to play with ohms law as sometimes your looking for only 0.something of an ohm .
I have owned a few older Ducati motorbikes and this was a common issue ...so I got good at sussin them out . I got a 906 Paso real cheap because even the local dealer couldnt sort it out ,a simple volt drop test was all it took to pinpoint the problem ....which doesnt say much for the dealer ....who also left the cam pulleys loose