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Alternator or Battery (or both)?

A couple months ago, I took my 2002 Hyundai Santa Fe (2.7L V6) to the dealer because the engine didn’t sound right (louder and less smooth). A little less than three and a half years ago it sounded very similar, and I took it to a local mechanic. He said something about the alternator bearings (I can’t remember what exactly the problem was), and he replaced or rebuilt the alternator. (Sorry, my car knowledge is poor.) Sure enough, this time around they said the alternator bearings were loose (or something to that effect) and that they could replace the alternator for me, but they also said it was still working properly and putting out the right charge or whatever. Since I was also having the timing belt replaced (which was shockingly expensive), I elected not to have anything done about the alternator.

Fast forward to a couple weeks ago: my car won’t start. My dad and I were able to jump start it, and we drove it around for a few minutes without any problems. Took it back home, waited a couple hours and tried to start it again and it did. However, the next evening I tried to start it again, and it would not start.

Is the problem the alternator, the battery, both, or neither? What’s the best course to take from here?

The car has 135K+ miles but hasn’t had any other problems (other than the A/C going out).

How old is the battery? At first glance, I would guess the battery. It sounds like the battery has a high resistance internal path for current flow. Some would say high resistance internal short. But there are other considerations.

You jumped it, drove for a few minutes, shut down and restarted. I’m sure there is more, but that description leaves the possibility that you only put enough charge on the battery for one start and you did not charge it enough after the second start.

I have to say that it is kind of unusual for bearings to go out in an alternator this early in the vehicles life, and certainly not twice. As the bearing wears out, it will allow the rotor coil to wobble around and tear up all the coils inside the alternator. You could have a new bearing set put in, but I think that something is not right with the rotor coil, maybe unbalanced or off center or bent slightly. A remanufactured alternator might be your best choice.

I doubt the dealer quoted you for a reman, they usually do new only. You will need to go to an independent for this, but insist on a quality remanufactured alternator.

There’s no need to guess. Jump it & drive it to the nearest auto parts store - most will test the battery & charging system for free.

And keith is likely right about the driving it around for a few minutes. This didn’t put enough charge on it. The best thing to do after the battery has been run down is put it on a charger.

I’m not sure how old the battery is, but I haven’t had it replaced since I got the car (in 2006; it was my dad’s before that). I know it’s been replaced at least once, though, because the battery currently installed is Duralast (AutoZone).

I think I’ll drive it around for a while and then take it to Advance Auto Parts (their website states that they offer free battery installation, electrical system testing and recycling with the purchase of a battery).

Thanks for the responses. Any additional input is more than welcome.