OK, we had the warmest day of the year on Saturday (about 50 degrees) and my wife takes our 07 LT1 out shopping and is in the store for a little over an hour. When she comes back out, the battery is totally dead, I mean dead, not low. After it is jump started and running, nothing was found on (dome lights, headlights, nothing). She drives the car and let's it run about 45 minutes. The next day it starts right back up! no issues since?

Any ideas of what could have happened?

 

Possibly a loose connection at terminal. Has happened several times on my wife's truck.

 

Which terminal was the culprit? Battery end or engine compartment, + or -?

 

My wife's Infinitank has the battery under the hood, and it would always be the positive terminal connection.

If you jumped via under hood posts in the HHR, check there first.

 

Short trips.

Our did the same thing three months ago.

I always carry a portable battery with it now.

 

Interesting... This was a very short trip probably 2 miles or less...
Did your only do it that one time?