Battery/volt Gauge Gmt800

2500HD 8.1 · August 24, 2008

I have a 2005 Yukon Denali with the original battery (3.5 yrs old). I believe that the gauge always read a tic or two about 14. Lately I have noticed it reading a tic or two below 14 sometimes. The other day the it was reading above 14, but when I came to a stop and idled at a stop light the gauge dropped below 14. I just noticed this the other day, and I'm trying to see when or why it changes readings.

Is this normal or is it a sign my batter and/or alternator is going? Thanks

superjim · August 25, 2008

Your voltage output will vary a little with RPM and electrical load that is on the system at any given time.

Yours sounds like it is working properly.

Mine does the exact same thing at about the same voltage range as you described.

Try this... Turn off you AC and any other electrical things that are on.

Turn the ignition on... look at the gauge... note the voltage... should be right around 12...

Start the engine and let it idle... it will come up to almost 14... rev it just a little and it will go slightly ABOVE 14.

If it is doing that... all is well.

2500HD 8.1 · August 27, 2008

Thanks Texas Jim. I will keep an eye on it.

Lincoln30 · August 27, 2008

Over 14 (on the gauge, 14.5 when measured with a more accurate device) on my 99 only occurs when the truck has been sitting and the battery needs a charge. That alone is probably a sign that your battery is starting to get old and not holding a charge as well as it used to. Other then the over 14 condition, anything between 12-14 is normal and will change based on RPM and accesory use.

redvett · August 27, 2008

2005 & up trucks & SUV's have a charging management system that actually shuts off the charging of the alternator when the battery is fully charged,this is to improve fuel economy. You should see the VM will toggle from a charge @ 14.3V to around 12.3V.

satori · August 28, 2008

2005 & up trucks & SUV's have a charging management system that actually shuts off the charging of the alternator when the battery is fully charged,this is to improve fuel economy. You should see the VM will toggle from a charge @ 14.3V to around 12.3V.

Good to know, thanks. I'm still getting to know my '05 Tahoe that I got a week ago. It does this and I was wondering about it.