2007 Sierra 6.0l

[ddp1960]

I have a 2007 Sierra 6.0L with 50,000 KM (30,000 Miles). This week it would not crank so had it towed to the dealer. They replaced the main fuse panel and starter.

When I picked it up I took it on a 1 hour highway drive. I noticed the volt meter up well over 14 volts, maybe 15 or 15.5 volts. After a while it dropped and now it jumpes any where from about 12.5 volts to 15 volts when I am driving.

 

What is the maximum reading I should get on the voltmeter?

 

I checked the battery voltage after driving and again after sitting over night 12.6 volts then 12.3 after overnight. Do I have a battery issue?

I put a battery charger on this morning and it only charged for a few minutes then said charged (12amps).

 

When I check he voltage with a multimeter, I only get about 9 volts from the battery positive terminal to one of the fender bolts, so I am also wondering if I have maybe a bad ground?

 

Thoughts?

 

Thanks

Doug

[dreisenauer]

^{Each cell has 2.1-2.2 volts so a reading from your battery should be 12.3-12.6 volts with engine off.Engine running, the alternator should produce 12.5-15 volts unless it's at full charge because your battery is dead, then it could go up to 18.}