1990 honda civic dx hatchback battery problem?

[HondaBoy]

i recently bought a 1990 civic hatchback dx and im having a battery issue. everytime i go to start my car, it needs a jump start. but say, for instance, if i drive it around and i park it and shut it off, and run inside a store [for example] for 5-10 minutes and return back to the car, it doesn't need a jump and it starts just perfectly fine. but then, when i go to work, park and shut off the car, and come back 8 hours later, it wont start or turn over at all, period! but then, i hook up the jumper cables real quick and it fires right up on the first try. what the heck is going on with my car? im afraid to go spend $80 on a new battery if its just going to die like this one. anybody help?

 

[Mr. KnowItAll]

Replace your battery. It's old and won't hold a charge.
They usually only last six years or so.