Interesting that I saw this thread...about a month ago after not driving my KJ all that far for about a month before that, I found it with a dead battery. I had accessory and dash power, just not enough to crank the motor. I drove it for 40 miles on the highway and it started just fine for the rest of the weekend. It sat for two more weeks (I travel for work) and when I came back, the battery was dead as a doornail. No power to anything, not even the door locks. The first time I thought it was just because I didn't drive it enough. The second time I knew I had a drain from somewhere. I wired my XM Sattelite Radio and Yaesu Ham Radio via the cigarette lighter accessory port at the bottom of the dash and had left it plugged in. Well it turns out that neither device was pulling from the battery, but the Radioshack two-way 12V splitter I have was providing the draw with an LED on it to let you know it was powered. A simple unplug of the wire from the accessory port made everything better.
So a $50 battery charger (which also is not a bad investment, as I used it on my brother's car after his door got stuck open from ice and the light stayed on overnight) and a few hours of time later, mystery solved and it's been fine ever since. You can't help a bad battery if yours is a few years old and endured some cold winters, but at least for mine which is 3 months old, I knew that shouldn't have happened. Check where you might be drawing from and good luck!