About a month ago, I went into the store for 5 minutes and came out - battery dead. Got a jump and went to buy a new battery.

Now a month later, I stop at the mailbox on the way home for 30 seconds and the car won't start...battery dead.

Do I have bad wiring or something?

 

You need to do some testing with a multi-meter. Battery voltage, voltage at the starter, & alternator output voltage are some good places to start. Check all of your grounds, etc..

 

You have a parasitic voltage drain. Check out the link blow on how to track it down. Its pretty straight forward and shouldn't take too much time to track down which circuit the drain is on. Good luck...

http://www.wikihow.com/Find-a-Parasitic-Battery-Drain

 

Thanks for the input. Turned out to be losing contact due to corrosion...go figure it was so simple.

 

A major drain will not kill a battery in 5 minute.

Check the charging system.