2007 GMC Sierra Repair Question
Mileage: 85,000 miles.
Should the volt meter drop to 13 volts when the batt. is charged while driving
Thank You
Tom Brown
Answer
no, fully charged it should be 14 to 14.5. when it is charginf, it will lower to 13.9 or so till the battery is charged.
Roy
So your saying the volt meter should not go below 13.9 or so. It does go down to aprox 12.5. I don't thine the daeler is testing it long enough to see this Right or Wrong ???
makes sense. lets put it this way. when the voltage is low, like 13.8 to 14, the alternator is pumping out high amps. when the voltage is high, like 14,2 to 14.5, the alternator output in amps is low.
it should never go below 13.8 or so. if it does, there is an internal issue with the alt.
Roy
SAME PROBLEM....last week My battery died,,change the battery and got a new alternator and now the amp starts off at 16 amps then drops to 13 and alittle below..It always seem to run higher before I had work done on it. Is this normal? If everything is charged what should the amp be? This is driving me crazy. I feel like I got a bad alternator.
you are referring to volts, i assume.
fully charged battery should have 14.5 volts at the battery when running. if you turn on headlights, wipers ac and defogger, the voltage will drop to about 13.9 or so but the amps will increase to the battery.
I would have a voltage drop test done from the battery to the alternator to see if there is any high resistence causing this issue
Roy
can i do a voltage drop test on this vehicle myself or do i need to take it to a mechanic. battery is reading 12.6 volts with car off. thank you
what is it when it is running??
yes, if you know how to do it. do you have expierence at this type of testing??
Roy