Battery problems 1987 XT GL

My 1987 XT has all of a sudden decided to run the battery down in a few hours. the battery is new and I cant find a draw or short from anywhere.

Got to work yesterday, everything was ok untill I started to leave, the battery was dead. I got a jump start and the volt meter was registering 13.5v. got to the house (2 miles away) and shut it off. The car re-started just fine (5:00 pm) by 9:30pm it was dead again. I took the battery out and set it on a trickle charge all night. This morning I reinstalled it and went to work, disconnecting the battery when I got there. When I left, I hooked it up and it started fine...

I figured if the battery was bad it would have trickled down sitting there, but it didnt. I did notice that when I reconnect the negative cable there are a few Faint sparks coming from the post, but everything is shut off.

Any ideas on what else to look for?

Keeb~