Battery voltage fluctuating.

[a4edwin]

Was curious about this when I start up the Denali voltage is at about 14v at some point it drops down. From what I can remember it was always close to the 14v within the past few days I’ve noticed the drop. Is this something normal or is my alternator going to kick the can?

 

[swathdiver]

Was curious about this when I start up the Denali voltage is at about 14v at some point it drops down. From what I can remember it was always close to the 14v within the past few days I’ve noticed the drop. Is this something normal or is my alternator going to kick the can?

Working normal. Look up Regulated Voltage Control and Electronic Power Management, RVC and EPM to understand how the system works.

If it was high for a few days, it was probably charging up the battery because it had been sitting or your runs weren't very long.

 

[a4edwin]

Copy! Thanks.

 

[me88]

The alternator output is reduced when the battery is fully charged and the power draw is relatively low (=fuel saver mode).

 

[Doubeleive]

while I agree it is normal, I personally would keep an eye on it, one of the indications of the battery getting weaker is the voltage fluctuations it should stay mostly around 14v but may drop on a long trip (economy mode, search GM RVG online), etc but if it is waggling all over a lot that could indicate that it's time to look at a new battery. Keep in mind also that this is the time of year (weather) change that will take out millions of battery's, same in the Fall.
for instance if the lights are on and you turn the blinker on and it is moving back and forth that's not normal

 

[a4edwin]

It just moves between those two points. Stays steady regardless if the hazard lights are on or anything is on

 

[mikez71]

Turning on headlights or tow mode should bump it up from the economy mode..

I just purchased a cigarette voltmeter I see everybody else using, thinking about adjusting the voltage for my AGM battery.. (If it looks to high or too low..)

 

[a4edwin]

Turned on the tow mode and the voltage gradually went up. Thanks.

 

[me88]

Also worth nothing: If you're running a Range AFM module it'll never enter the fuel saver mode, charging voltage always stays at about 14.5V.

 

[mikez71]

I keep reading AGM needs 14.2-14.7 volts.. Could be that is for steady state charging and maybe the lower voltage is OK when battery is fully charged..?