so i have a 90 cavalier z24 and the other day i was listning to music while waiting for my girlfriend like always but i dont run the car usually.So i turned it up to test out the subs cause i bumped it up to 200 hertz and wanted to see what it sounded like for like 4 seconds then turned it back down,then started the car and smelled a burning smell and then battery wouldnt charge so now i am screwed cause i can jump it and it will run for about 2 minutes so i just got a new alternator and put it in and still doesnt charge.Any help would be appreciated thanks.

I would have got a new battery first, or at least tested it.

well the battery will power things when jumper cables are hooked up but when you on hook them it just starts dying and then car shuts off.

So you're saying that the battery will run things when its connected to another battery? Hmmmmm
Get the batt checked

check the fuse or fuse link for the alternator

First get a digital meter and test the volts the battery is at? 12.9 volts. It should be with charging ready 13.9-14.3 while the motor is running. If it doesnt get those readings I will think about replacing the battery.