awsomethunder

what is charging system voltage.my friends gauge reads alittle over 13 volts.i thought it was just over 14 thats what my gauge reads.his marine is telling him he needs a new alternator.how do you check this?

Airpacker

check the voltage above idle at the battery terminals. Lots of difference between gauges. Voltage drops between engine and dash as well as poor grounds can effect the reading as well. Voltage above idle should be between 13.6 and 14.2 ideally.

hillbilly24

You also need to check the current the alternator is producing, that's what charges a battery not voltage. Depending on the model the diodes also need to be checked to insure that the alternator is not drawing current whiel teh engine is shut off and killing the battery.