I have had battery and alternator checked, both are good. Battery was dead, jumped car, started and ran fine. Drove 30 minutes, shut off and sat for 2 hours. Started fine again, just went to gas station and back. Sat 15-20 minutes. Started again, ran 30 seconds and everything shut off, no power at all, battery completely dead.

Alternator is the correct diagnosis.

Maybe the alternator is draining the battery. Have the alternator tested

battory is bad it runs fine just altoter is runing so buy a battory and it should work fine

Sounds like you need a new battery and an alternator. You can have both of these parts checked at your local AutoZone or parts store.

i have the exact problem.im trying spark plugs

If your battery is bad, you can jump start it sometimes but it's running off your alternator...After doing this many times it will kill your alternator also..You can go by almost any auto shop and they will check your battery and alternator free...But it sounds like the battery

replace the alternator,this is the problem,please rate thank you.

you ay have a faulty alternator have it check and serviced

check to make sure the alternator is charging the battery.crank engine while idling the alternator out put should be 13.5 volts to 14.5 volts. if not alternator is not charging the battery.if alternator is charging battery.the battery is weak.if its over 5 years old its more likely battery.if battery not old checks out good .replace battery cables..

At first blush, sounds like corrosion on the battery cables either at the battery or at the other end at the alternator or starter. There are several sprays at the auto parts store that will clear the corrosion but the best way is to remove the cables and clean both the cable ends and the posts. Once you're able to rule out the cables/connections having the charging system checked would be next point of order but its more likely to be the cables. A car that won't run on it's own isn't getting enough power from the alternator so I'd check the negative cable first.