Dying Battery

[wildfowler]

New here, just found this forum and would like to ask a question.

 

I've got an 06 GMC sierra SL 4x4. It's got automatic transmittion, manual everything else. The truck is equipped with a single battery. I have a sirrius (FM transmitting) radio receiver that plugs in to the cigarrette lighter to get it's power. I normally leave the reciever plugged in and powered on. My problem is that if I don't drive the vehichle within the next 18 hours +/-, my battery will be dead.

 

I've never had this problem on other GM vehichles in the past. The dealer found no issues when I brought the vehichle in. The truck is now out of warranty. I have replaced the battery with an interstate MT-78 battery. There's still a problem. Actually, the problem occurs if cell phone charger is plugged in, or if anything is plugged in for too long.

 

The simple solution is to remember to unplug the device. But that doesn't always happen. I would like to know if this is normal, or if there is a way to diagnose a problem that can be corrected. This is mainly an annoyance right now, but has the potential to leave me stranded.

 

I'm convinced that there may be a short or other problem that could be discovered, but I don't know where to start.

 

I appreciate any help or suggestions.