Ok, so there was a hurricane that ran through here not too long ago - Hurricane Ike. After said disaster ran through, we were left without power. My family killed the battery in my car, which then had to be jumped.

It was fine, but when I tried to start the car a few days later, it only had enough battery power for the electrical needs. The starter wouldn't even click. As is stands, if I don't start it up every other day or so, it happens again. I've had the battery and the alternator tested and they said they're fine.

Yesterday, drove the car around after getting jumped, and then put it up in my garage. I tried to take it out this morning, and it needed another jump. If the battery and alternator tested fine, then what could be the problem here? =\

 

Did any parts of the car get wet?
Are the terminals on the battery definitely connected properly?
Possibility it's the starter solenoid.
Where was your battery tested? How did 'they' test it?
Is it in Park?

 

Nothing's wet, the terminals are new, the car's in park (xDDD), and I believe the solenoid is somewhat new, but good idea.
I got it tested at AutoZone. They connected a tester to it and whatnot.

 

They did a properl load test I assume? They didn't just put a volt meter on it?

 

It sounds to me as if you're battery simply isn't holding a charge, at least for more than a day or two. One way to be sure would be to test the battery (with the autozone loadtester) once the car won't turn over. Not sure Autozone will let you leave with the tester. Maybe if you leave your license?

 

He shouldn't need to. The load tester will simulate the cranking of the engine.

 

I'm not a mechanically endowed individual, so I'm not sure what kind of test they performed. All I know is they rolled out a machine, hooked up some jumper cables, and said it was fine.
We tried when the car wouldn't start. We took the battery out of it, took it to AutoZone and they checked it and said it's probably the alternator. Next day, I took the whole car there, and that's when I saw them test both with the machine. For the alternator, I had to run the engine at 2k RPMs, if that helps.

 

-edit because I just saw magiusavvail's response -

Let me get this straight, your car always starts when jumped, though?

 

Yes. After a short jump, it starts right up and runs for the rest of the day.
Yesterday, it ran all day. Sometime during the 12 hours or so that I was at home and/or sleeping, it lost enough power that I needed a jump this morning.

 

What about the voltage regulator?