alternator reading

[George Pyrpiris]

Was wondering about my alternator charging at 15.3 volts.  This is the reading I get from both banks when motoring.  I suspect this is a little high, I had heard that 14.5 volts was more the norm.  Should I be concerned?
George
#195 FKSR

[Stu Jackson]

George, in order to help, we need some more information.  While 15.3 is too high, what alternator do you have? OEM with internal regulator, or an upgrade with an external regulator.  If the latter, the regulator could be set to equalization  voltage and can be corrected.

For a good understanding of what batteries need, go to www.amplepower.com and download the Ample Power Primer.

[rirvine]

It would also be interesting to know what volt meter you used to measure the charging voltage. I would put little faith in the reading from $5.00 meter that are standard equipment on the C34.  Before you get too excited, measure it (at the battery) with a quality DVM.

Ray

[George Pyrpiris]

Stu, previous owner switched original alternater with a 55 amp mercury marine model #817119-2 with internal regulator (I am assuming that the black box on back is the regulator).  I used a new digital voltmeter and the reading is actually between 14.9 and 15.  The 15.3 I get from the installed voltmeter at the nav station.  I may just buy a new one and keep this as a spare.
George

[Ron Hill]

George : Most batteries do not like much more that 14.2 V while bulk charging!!
I'd believe your digital Vmeter.
If you don't want to spring for a battery monitor at this time here's a suggestion.  Go to Radio Shack and buy two female banana plugs(one red and one black).  Then wire them to the same connections as the Vmeter on your panel.  Then you can easily plug in your digital meter and read volts. 
I wrote this up in the Mainsheet tech notes well over 15 years ago.
A thought.   

[Stu Jackson]

George, you are steadily killing your batteries.  If it was my boat, I'd have the alternator and regulator checked before I (conintually) cooked (and overcharged) my batteries.  The investment in batteries, even if you only have 2 or 3 (at $50 to $100 each) is worth taking the alternator off and getting it and the regulator checked, right away.

[Footloose]

George,

Take your alternator to an automobile shop that repairs alternators and starters.  They will test it in about five minutes and can make any needed repairs for you.

Dave

[George Pyrpiris]

Dave, took your advice and brought the alternator to a marine alternator and battery shop...the regulator was acting up!  $35 repair, I'll install tomarrow and see for myself.  SHop sells new alternators just like the one I have for $130.
George