GT-40 Alternator

[toddrswenson]

What should the voltage be at the battery when the engine is at idle? I'm trying to track down if my alternator is going out. I know in cars its at around 14 volts when running.

How do you check the voltage directly on the alternator?

[Chexi]

Between high 13s and high 14s is what I get on mine (after swapping out my bad one with the 100A kit). I used to go from 12.5 at idle to nearly burying the needle when going over 10 mph. Bad voltage regulator. What are you showing?

[toddrswenson]

It's bumping to 13 when cruising. 12.5 at idle

[mklaaijsen]

On our previous boat the voltage meter in the dash was showing barely 12v.
When tested directy on te batteries or the lead coming from the B+ termial on the alternator we measured 13.8 - 14.2.