[DML] battery problem

[rickaye@xxxx]

i i went out to my delorean for a short trip to the store, i learned
that my battery was dead. since i have had the car, this has not
happened. i quickly jumped off the car and was on m way. for saftey
sake, i parked on a hill, in case there was a need to jump start the
car. well the trip to the store was find, so the altnator must be
fine. i was right though, i had to jump start the car . the trip home
was agian fine. i even cut the car off and then re started it. i
think that i may have accidently turned on the defroster button the
other day. is this what could have caused the drain on the battery? 
also the battery is agian dead today. is this because i didn't put a
charger on the battery ? i thought that the trip to the store would
have allowed the altinator to have charged it enough. also does the
right side passanger door need the post extentions that shut off the
aviator lights on the doors? or maby is it that i just need a new
battery ? any help would be great.

p.s. - does anyone know where to purchase the ultima battery.

thanks
officer rick