The back story to this is a cold start issue which I fixed with a few glow plugs and a Whites and Rogers relay. The truck seemed to crank really slow, slow enough that it did not register on the tach, but it almost always started on the first crank and always started on the second crank no matter what.

I was expecting things to get a bit better with the weather being ~50* during the day and staying ~40* at night, but that hasn't been the case. This got me thinking so I have been watching the dummy voltage gauge on the dash panel. I can see the GPs turn off if I wait long enough and the truck usually starts above the normal operating voltage lower limit on the dash panel gauge (for arguments sake we'll call that ~10 volts). The last few days it looked like the voltage was a bit lower than normal, right at that lower operating range marking and I felt like the truck was a bit harder to start (atleast I don't think it was in my head). This afternoon, the truck dropped below the lower normal operating mark while starting and definitely was cranking more slowly, but it was still able to start.

So, after my commute home, 1 hour, I let the truck sit for about an hour and went out to check the batteries with my volt meter. Both batteries read about 12.75 (disconnected both leads before reading). I hooked everything back up and went KOEO which read out to 11.58v (this would be GPs on) then cranked the engine. The voltage dropped to between 10.4v and 10.9v before the truck started. With the engine running, the alternator reads 14.35v and the batteries read 14.3v.

If you're still reading, does the charging voltage sound right? I know the truck needs 10.7v to start but most people are seeing more than that while cranking. My batteries are both Duralast Golds from Nov. 2010 1000 ca and 850 cca. I will test again after the truck sits to see if I have a drain on the batteries, but the voltage always seems normal until the truck starts cranking. Any thoughts appreciated.

Here's the video of starting the truck after I got home from work:

 

Does this sound like normal wear on the battery and its time to bite the bullet or is there a charging problem possible?

 

The charge voltage is good, and the drain voltage is slightly lower (but not much) than my two-year-old batteries. My starter cranks strong. You could have a weak starter or maybe we're comparing my synth oil to dead dinos... I dunno.

 

I am running supreme 7000, but I didn't notice an improvement with the weather like I thought I would. Would the weak starter use more power to turn or turn more slowly and use less power?

 

A bad starter typically uses normal juice, but doesn't crank strong. I listened to your starter cloesly and it spins nice, there's just that first wurh before she cranks good. You may not have a real issue, it's so hart to tell when the truck fires up so quick. Here's a cranky truck after all fluids were drained and refilled.

 

Thanks Rich, yours definitely cranks faster then mine. But it looks like you are garaged in addition to synthetic oil. I got both batteries warrantied at autozone last night, which is good because they've gone up $30 a piece since I bought them. I took a video on start-up this morning but the glare from the flash light on the voltmeter screen make is illegible. The truck started easily though.