Hi everyone, I just took advantage of GM's huge incentives and upgraded my 09 Sierra to a new, 2013 Sierra z71. LOVEEEE it!! Being the stickler for details that I am, I noticed that the Variable charging rate system that fluctuated between 12-15v on my 09's volt meter(as designed) hasn't varied at all on my 2013. I only have 300 miles on the new one. I realized(from service manual) that many conditions have to be met to lower the voltage output, but I think I am meeting those conditions and the volt meter hasn't dropped off 14+ at all. I even topped off the battery with my C-Tek charger overnight and the battery is fully charged. Anyone have any info on this? Is it because of low miles on truck?