1998 battery issues?

My 1998 jimmy has trouble starting in the morning. I usually have to jump it to get it going. I have had the battery tested, and it has full charge. Its not the alternator. Any suggestions on what i should do to prevent this from happening to me again. Once i get it jumped in the morning, it does fine all day long...thanks for your help, donna

sounds like something is staying on in the electornic system.
i have a 93 gmc truck if i dont pull the fuse to the radio and let the truck set 2 days it will drain the battery.
might have someone check and make sure you dont have a power drain somewhere

How did you test it, did you have it load tested?