Alternator charging indication
Thread Starter
Burning Brakes
Joined: Mar 2021
Posts: 998
Likes: 388
From: Tyrone, GA
Alternator charging indication
Today is a beautiful sunny day and 50 degrees so I decided to go for a top-down ride. I got the infamous click-click-click when I pressed the start button. I know what a low battery sounds like and I figured it might be down a little since the weather has been so bad here. I jumped it and it ran fine, however, the battery charge gauge showed about 15 volts and it never moved at all even at idle. No car I have ever owned did the charging voltage stay the same from idle to cruising rpm. Do any of you know if that charging gauge should vary with rpm?
Le Mans Master
Joined: Oct 2014
Posts: 8,673
Likes: 2,728
From: Atlanta GA
C7 charging systems are controlled by the ECM , and voltages will vary from a low of 12.6 to 15.4 . An alternator WILL not charge back to normal levels a dead battery, hence the reason why it was showing 15 volts. The alternator will eventually fail trying to maintain this level of charging . On the older style alternators trying to charge a really low battery would result in a fried Diode Trio , a trickle charger might bring it back to close to full charge but struggles because of increased resistance the closer it gets to full charge . . You need a real charger and slowly charge it back at a rate of 4 to 8 amps . HARBOR FREIGHT sells an inexpensive 2 8 15 am computer controlled charge that works great
Dave
Dave
