Varying voltage on 08 Denali

[dammad]

My 08 Denali has had the common no start GM gremlins for some time, perhaps occurring every few months. But now on the holiday weekend I've had it twice in 24hrs. No start but other electrics worked.

I had the battery, connections and alternator checked at Autozone. No problems. It's going again now but I noticed that the volt meter (don't have a DMM handy) varies. Initially on starting its about 14.7v (this is what Autozone measured). Then after some time (30mins to many hours) it drops to 14v and down to around 13.3ish after driving for a while. It sits at 13.3v but rises to 14v on idle (traffic lights).

I hadn't noticed before, but is this type of variation normal or a symptom of a flaky battery/voltage regulator.

Haven't have the body control module reflashed but am tempted to after the holidays.

Thanks and happy memorial weekend!

 

[soulsea]

The voltage fluctuation is normal on these trucks.

 

[Kolt-46]

It's a power on demand alternator.

 

[NathanJax]

The voltage fluctuation is normal on these trucks.

It's a power on demand alternator.

^^^^ this ^^^^

 

[Modded]

Your voltage is fine as mentioned above. The starter could be intermittently faulty or its connections are loose.

 

[Denali0229]

My voltage is usually all over the place according to the OEM volt meter. I've seen it as low as 11-12ish and as high as 15-16ish. I only have stock electronics in my truck at the moment. Seems fairly common.

 

[Modded]

My voltage is usually all over the place according to the OEM volt meter. I've seen it as low as 11-12ish and as high as 15-16ish. I only have stock electronics in my truck at the moment. Seems fairly common.

Hmmm, the lowest I ever see is 13 volts.

 

[Denali0229]

Ya, that's why I don't think its very accurate. I'll probably just buy a voltage meter. They're only like $20.

 

[dammad]

Great. Thanks for the confirmation it's normal. I'll look for bad connections on the starter circuit.