Curiosity - Charging Voltage

Wxman · December 21, 2017

Just went over 2250 miles on the 2017 LT doing some errands today. I was used to seeing the charging voltage vary on my 2012. Not sure what the parameters were, but it varied with charge-discharge and temperature. I had noted to myself that the 2017 didn't seem to do that. I don't recall ever seeing the volt gauge drop more than a needle width below 14, until today. Today I noticed it running well below 14, closer to the low end of the normal band most of the day. It would run over 14 immediately after start, but quickly dropped.

Not worried, just curious why I didn't see this on the new truck until now. Don't think I changed anything. Same trips I commonly make. Weather was nothing different to speak of.

Any thoughts!

sdeeter19555 · December 21, 2017

Mine varies between 13.9 and 15.2vdc depending on the day...and that's a 2012. I think it's normal since they use temperature to determine charge rate, among other things...

Steve
2012 2500hd 6.0l

swathdiver · December 21, 2017

Electrical Power Management is the system that controls the alternator output. When the battery is near a full charge, the alternator either turns off or its output is low. The BCM measures and controls all of that through the Battery Current Sensor which is attached to the negative battery cable right near the battery on the GMT900s. If your lights flicker or you're worried about it, unplug it. On the GMT900s it does not set off a CEL and the alternator reverts to full output all the time.

Wxman · December 21, 2017

I am not really worried about it. I was used to it in my 2012. I just thought it curious I hadn't noticed I,t in two months and 2k miles, until today and then today it stayed low nearly all the time.

Nasty · December 22, 2017

05+ have a battery current sensor. Lowers voltage to "save gas" IT should fluctuate between 12.8 and 14.9

seamus2154 · December 23, 2017

Perfectly normal on these trucks. Had the same question for my service rep as mine was below 14V one day. He explained if I am fully charged and no demand the alt will turn off and on as needed. My new '17 does the same thing as my '15. No issue.