Please help!!!

I was driving down the highway, and my car suddenly quit as if the key had been turned off. When I tried to re-start it, all it did was click repeatedly. I bypassed the ignition relay to see if the car would turn over, and it did.... 1/4 rev. Should I start with the battery or the alternator? What does the problem sound like to you? I don't have the money to experiment... and I am ignorant to if the car runs off the battery or the alternator when driving normally.

Thank you!!

While running the car runs off the alternator. The battery is there to start the car, but also helps a little in running accessories. It sounds like your alternator went bad. Before the car quit, did you notice any of the dash lights, radio, or anything start to dim? Try this, get the car jump started, it should start unless there is something extremely wrong with the car. When the car is running, disconnect the negative side of the battery. If the car dies, then the alternator should be the culprit. Most auto stores have free testing, so you could verify this method by having it checked out at one.

Most Pep Boys/Checker/Auto zone etc.... will test free.I would suggest the Interstate or Optima (same unit) gel filled maint free battery.(red top)
Great cranking power and great longevity even in the Az. heat.
I sell them but only to local customers as shipping and my price can be beat by most as I stock 6 batteries at a time.
I sell them for about 109.00 you could check Costco/Price club I think there 80.00 and well worth the extra few bucks not to loose your car over a bettery.
The big joke in AZ. being its so darn hot and batteries die so often we should lease and not buy them.While your at it see if some supporting vendors Dario over at Steeda or Sean at SHM,or rousch carry a battery relocation kit to mount in trunk.The battery will last longer due to a much cooler operating enviornment and 40 lbs. off the frt and to the rear will pay off a bit with a 1/4 mile run.
Again IMHO make sure its the gel battery so if it tips it wont spill and corrode whatever metal it comes in contact with.Good Luck,Dave S.