Battery keeps draining

I have a 2000 Eclipse GT that I have only owned for 8 months. I had no problems out of the car until about three weeks ago when it suddenly wouldnt crank one morning. I took it to Advance Auto Parts and they said the battery was bad because my amp had drained it too many times and they put a bigger battery in. Well, about a week later, the car wouldnt start again. I took it to the Mitsu dealer and they said that the new battery was too big and that the terminals were touching the metal of the hood and that was causing it to drain. I took the car back to Advance and made them put the right size battery in and i had no problems for two more weeks. The car started fine this morning and I drove it to work but when I came back out, the battery was dead again. I dont think that my amp is the problem because I had it on the car for 5 months with no problems. Im a poor college student who really cannot afford another trip to the mechanic (im already having to get a new A/C compressor installed, that conveniently went this week too). Does anyone have any suggestions or has anyone else experienced something similar? Any help would be greatly appreciated.

If you're running a big sound system in your car you might wanna look into an optima yellow top battery. I hear they recharge quickly and are made for people running a lot of power draining accesories. It also shouldn't have any problems touching the hood or anything like that either.

I don't think that it is your battery is the main problem. I think that it is your alternator. The yellow top battery will help but if the alternator is not recharging the battery it is not going to do you any good.

i would get the alternator checked like cficare68 said

you may want to look into a power cap for your system.. i used to have the same problem with my prelude till i got my power cap. then no more problems

I don't know how big of an amp that he is running but i highly doubt that an amp is going to run down that many batteries in that short of time. Heck a have a 2500 watts RMS amp and i haven't went through any batteries. Right now a cap is not going to help him battery any. Cause it sounds like he is running off of straight battery if they are draining that quick.