Having read about a few others on here lately who have had some battery issues, I am passing along something I found tonight on my truck.
At times I have experienced a weak battery and the sight gauge on my battery often shows red. My trucks battery will drop down to ~9 volts when it cranks and then back up to 13+ volts after it is running.
I was looking to upgrade my "Big Three" this evening and happened to run across a grounding problem on my truck. What I found was one of the ground wires from the fender to the wiring harness was not tight against the fender. The bolt was very tight, but I could move the cable in and out on the bolt. Below is a picture of the location I am talking about on the passenger side fender. The cable in question is the one on the right and the picture is from after I installed an additional ground cable to the location as a part of my upgrade.
I am hoping this will make a difference going forward as I clearly was not making a solid ground on this wire to the body.