Here's the scoop,
The car turns over (cranks) a little. my friend comes by and boosts it. it fires up no problem. i drive for 5mins and the car's lights and radio and everything dies on me and the abs light comes on. then the car dies. it barely cranks. then my friend boosts it again and it start up but dies 5mins later. does this seem like an alternator problem or battery? the alternator was changed in february this yr. the battery has died on me a few times because i drained it with an air compressor. My conclusion is either:

1)alternator
2)battery
3)short somewhere.

I figured that after the boost the alternator would charge up the battery and keep the car going but it doesn't! Does the battery serve any function after it has started the car? If it does serve a function, then I guess that a bad battery could cause it to slowly die like that.

any ideas?

 

Both.

Check the voltage with the car off at the battery. Should be 13.6V fully charged. Start the car, now the voltage should be 14.4V with a healthy charging sytem.

Given that all the warning lights came on (alternator) and the car is slow to start and needs a jump (battery), I'd say both need replacing now.

 

if the battery puts out 12.6 with the car off, you're good. the cells in the battery (6) should be 2.1v-2.2v, so 12.6v-13.2v. the battery and alternator power off one another once the car is started.
also, "shorts" aren't as common as people make them out to be. its become a term to describe an electrical problem.

 

Hey thanks guys for the tips! I bought the "big daddy" eliminator battery from CT. Anyway, the car fired up no problem and I drove it for 40mins or so and shut it off in between. If the alt was bad I'm sure the car would've died again despite it being a fresh battery, right?

 

just take both to auto zone or advance auto, they'll test 'em

 

nope car will work for 1-2 hours with no alternater and a new battery.

while running check the voltage across the battery. should be 14 or so volts.

if the alt is dead. fix it now. otherwise you will damage that new battery as well.

 

update, car died again. i think it is alternator. having it checked now. i'm sure that they will recharge the battery before giving it back to me and the battery should be fine.

 

A problem with the primary wire from the alternator to the battery will also give those symptoms.

Measure the voltage drop from the alternator post to the battery + while idleing with the lights on.
It should be less than 0.5 volts.

 

So did you ever find out what was wrong with your car? Mine is strting to do the exact same thing! Just replaced the alternator too recently. Maybe problem with wires?

Ken

 

impressive n00b...most impressive. But you are not a jedi yet.