Question

I have a 2006 GMC 2500 HD duramax LBZ - recently the truck has not been starting in the morning. Seems to be a battery issue but after testing the batteries they are both good but when I turn the key to start the voltage is obviously low (about 5 volts) and the truck will not start. Either it will click when the starter is trying to engage or it will do nothing. The lights in the cab are on and actually are not dim as would be expected. It seems the issue is completely related to the starting of the truck. Air will blow out of vents, stereo works, etc. I put the charger on the truck for about 30 minutes and then the truck will eventually start. During the day as I shut off and restart the truck it works fine but after sitting overnight the issue happens again. I did install the Edge Evolution a while back but did not have any issues at the time of installation.