Strange thing. My truck sat for a good week during the holidays, and when I went to start it the battery was dead. I figured well it sat for a good week and it has been pretty cold here so I will just jump it and let it run for a bit after I get home from work that night. Got home, threw some cables on it and it started right up. I let it run for 10 min or so and then turned it off. This morning I went to hop in my truck and head to work, but when I opened the door I noticed the light was dim and then went right off, turned the key and click click, battery is dead again. Never had an issue with my battery until now. Could it be that I didn't let it run long enough to get a good charge on it? Last night when I got it running I checked for any lights that may be on and there was none.

 

Could be a dead cell in the battery and time to replace it..

 

x2 you can always go get it tested at any autoparts store for free if you want to also.

 

Mine acted similar, and it was the alternator. Not a major job, just 4 or 5 bolts, really. However, I'd definitely get the battery tested, first.