Alternator Charging?

[cbr9rider]

Hey guys I just bought a 2010 silverado almost a month ago. I am one of those guys that watch there gauges religeously. Noticed that the charge gauge to me was acting kinda funny.

 

The charging hand when I first got the truck seemed to stay above 14. But like this morning on the way to work I drove to my moms to drop the baby off (8 miles) the charging hand was way under 14. I had a volt meter with me and checked at the battery with the volt meter. Read 12.8 volts at idle. So jumped back in the truck on the way to work another 6 miles the hand went straight to 14 and stayed for about 2 miles then it went back way under 14 volts.

 

My question is "is this normal for the new trucks or am I having alternator problems?" I had a 99 gmc sierra before this and like every other vehicle that I've had the alternator stayed charging all the time.

[5829BMG]

Mine does the same thing. Owners manaul states if theres a problem the charge LIGHT will illumninate. I miss seeing my alt gauge show 14 all the time,but you get used to it after a while.

[Matt_]

IIRC, the gmt800 gauges werent an accurate depiction of the alternator output.... they pretty much just stayed in one position unless there was a serious issue that would cause the voltage to drop and remain low for a long period of time.... it was like the "oil light" which doesnt come on until its too late.

 

in reality, your battery will read anywhere from 11.5-14.5 volts depending on the load,rpm and alt output. the newer gauges are a more direct representaion of whats going on with the charging system... fluctuations in voltage are normal; i wouldnt worry too much about it unless the needle is hanging around the 11-12 volt range for an extended period of time.

[kdixer]

"When the engine is running, this gage shows the condition of the charging system. The gage can transition from a higher to lower or a lower to higher reading. This is normal. If the vehicle is operating outside the normal operating range, the charging system light comes on. See Charging System Light on page 3-41 for more information. The voltmeter gage may also read lower when in fuel economy mode. This is normal."

 

This is from the owners manual. The battery does not require a constant charge rate.

 

 

 

[RJT]

The alternator on the nbs only charges as demand dictates it to charge. If the battery is fully charged it will not charge. This is for fuel savings supposedly. When towing an rv with a battery to charge you need to turn on the headlights. This will cause the system to charge.

[cbr9rider]

Good info guys. I appreciate it. I'm just glad I dont have to take it in for service.

[nickvrebel]

The alternator on the nbs only charges as demand dictates it to charge. If the battery is fully charged it will not charge. This is for fuel savings supposedly. When towing an rv with a battery to charge you need to turn on the headlights. This will cause the system to charge.

correct, also turning on Tow/ Haul mode will force the alternator to stay charging