I'm just bought an 09 Avalanche LTZ 6.0L a few weeks ago. The volts gauge was rock steady at 14 volts until this weekend when I noticed it down at 12.5 or so. I watched for 30 min on the way home with the intention of checking the voltage when I arrived. Just before I got home the gauge moved back to 14. I tried starting and driving it again and it never moved off 14. This was daylight driving with the ac on so nothing should have been cycling on and off. This morning I head out for work and I see the volt meter showing 12.5 or again. I get to work and check it with a muiti meter and sure enough its reading 12.65. I hooked up to a Snap-On D tec tester (for charging systems, starters and batteries) and checked it out. The voltage was 12.7 and the tester said the alternator was good (no bad diodes). So my question is, is the low voltage normal? I'm used to a charging system holding the voltage at 14 or so and increasing amp output as required. Thanks!