Car dies after battery runs out of power.

If alternator is charging properly you still may have A bad battery. Have battery load tested after fully charged. Also check for bad or loose grounds..

I have a brand new battery in it, it will run for 2 days then on the third day it will be dead

It's the second battery I've put in it new from store

talked to a electrical guy and i did a test with all fuses with a test light on the neg. battery post with the test light on the wire (off of the battery obviously) and i started pulling fuses and the only one that dimmed the test light was the courtesy lamps/ cigar lighter. but i haven't had a fuse in that for months and it was out before i even had this problem, im thinking the diode in the alt. might be bad hins the reason im losing juice with the key on or off.. if anyone has any other ideas throw them out there at this point nothing is wrong.. haha

My 1986 Chevy Cavalier was doing the same thing, alternator tested good. Nobody could figure it out. Finally I got a new alternator and it has been running fine ever since

Battery probably not ground properly and not getting recharge

I own a 1997 cavalier, & I have the same problem. Yes I switched out the battery/alternator even my spark plugs & the car has been sitting in my back yard for almost a year... & as someone in this forum stated the car does lose (charge) after each time it keeps dying... DRASTICALLY...... & when My engine is running & battery is about to give out my dash goes CRAZY!!! Lights and gauges go NUTS. but IF i punch the gas it “helps” the car stay on a little longer ,... for ex if im driving & I hear the car wanting to shut off & my (bat) light turns on I’ll punch the gas to “send” more voltage to my alternator for a small amount of time & keep my battery from shutting off completely