Nomad died after 750 mile trip

[cocheese72]

I came home last night 750 miles. Hours of it through hard rain. At the last gas stop it started OK, but when taking off, it felt like it was missing. Once on the highway, it was fine. When I finally pulled in the driveway, was running bad at low revs, stumbling. Finally just sitting there it died, and now will not start.

I am thinking it may be the battery. I ran heated liner and gloves on the way home. Checking the battery, it is under 12.6v, sitting right at about 12.52v. I have it on the tender now. I tried jumping it off the truck, but it would not start.

What's next to check after the battery gets up to snuff, in terms of most likely.