Is it my battery or alternator...?!?!?!?

Alternator for sure, possibly the battery as well. (bad alternator can kill a good battery) . Good alternator should have kept the car running.

Cirma is exactly right. Once the engine is running, you could take the battery out and it wouldn't quit with a good alternator. (Don't test the alternator that way. It can cause untold grief)

But once a battery has been completely killed a few times, it's not going to be very good any more, so you probably need both. Anybody who knows how to use a voltmeter can tell you if the alternator is working in 60 seconds.

I know a quick trick to see if your alternator is charging. You can take a wrench or a screwdriver and place it next to the rear center of the alternator when running while trying not to touch any of the terminals. If you feel magnetism there then it is charging, if not then it isn't. I don't know how many people know about this trick and I may get a thumbs down because they think im crazy. If im crazy then go out to your own vehicle and try it and prove to me that this trick doesn't work. I know it does and have been using it for many years for a quick diagnostic without having to use a multimeter.

Can't tell unless you get them checked. Could also be the battery cable corroded.

You can check yourself by getting a battery charger and charging the battery and then seeing if it holds the charge for a few days.

No Start, this procedure covers most makes and models.

No Crank: Check headlights

Headlights Bright – Try to crank – Click, no crank lights remain bright = starter or solenoid. Verify by checking for crank signal at starter using a test light while assistant holds key in crank position. Try thunking the starter lightly with a hammer while assistant try’s to crank engine if test light shows crank signal present at starter = bad starter.

No Click No Crank – check for crank signal at starter using a test light while assistant holds key in crank position. If crank signal is present starter is bad.

If no crank signal at starter check ignition switch and / or intermediate solenoid / relay on fender or firewall or clutch switch or transmission park/neutral switch. No power at ignition switch - check fuses and / or fuseable links.

If headlights dim or go out when attempt to crank = weak or bad battery or bad battery terminal connection – clean and tighten terminals, if still no crank replace battery.

Headlights dim or not at all – Battery discharged or bad. Charge battery, 30 amp charger 3 hours, 10 amp charger 10 hours, go back to top and start process over. While charging look for cause of battery run down, dome lights, trunk lights, glove box lights an so on.

IF you choose to attempt to Jump Start a car PLEASE follow the following precautions and procedure:

WEAR SAFETY GLASSES!!! Do not allow the vehicles to touch!

Connect one end of the Red cable to either the (+) Positive battery terminal or the Red (+) Positive Jump Starting Post of the vehicle to be started. Connect the other end of the Red Cable to either the (+) Positive battery terminal or the Red (+) Positive Jump Starting Post of the vehicle providing the jump. Connect one end of the Black Cable to either the (-) Negative Battery terminal or to a solid metal component, bracket, ect. of the engine of the vehicle providing the jump. Connect the other end of the Black Cable to a solid metal component, bracket, ect. of the engine of the vehicle to be started – DO NOT connect to the battery terminal for the final connection (Explosion Hazard!). Watch for sparks when making the last connection – if NO sparks, remove the final connection and wiggle all three of the other connections then make the final connection again. When you get sparks when making the final connection it indicates that a good connection is being made, capable of carrying the load of charging and starting the dead vehicle. When connection is complete, start the engine of the vehicle providing the jump start if it is not already running, and wait 10 minutes for the dead battery to take a partial charge. After 10 minutes the vehicle being jump started should start normally. If jump starting is successful and no obvious cause for battery to be dead (Head lights, dome lights, trunk lights glove box lights an so forth left ON by driver), the vehicle should be taken directly to a parts store for a replacement battery.

Cranks - no start – Got fuel? Check for Spark using a spark tester or spare spark plug. Spark ok (check all 3 or 4 coil packs if multi coil ignition system) Check fuel pressure – special gauge required on most vehicles – refer to factory specification for correct normal pressure and procedure. No spark at one coil, normal spark at all others = bad coil or harness connection.

No Spark at any coil – check crank and cam sensors (DRB Test) Check valve timing (belt busted?) Full system DRB (Diagnostic Readout Box) analysis at repair shop.

Hope this helps 