Alternator issue

My experience is from working at a very nice Chrysler dealership. There, if the problem was documented, as in written up on a service order, and the problem showed up again out-of-warranty, Chrysler would still cover it under the original service request. You can ask if Hyundai will do that. They seem to be a very customer-friendly company; just the exact opposite of GM and Volkswagen.

It is somewhat common for generators to be intermittent before they fail completely. The problem is due to worn brushes making intermittent contact. That isn't a serious repair but most people just replace the entire unit. Mechanics always replace rather than repair because it gets done faster and with a better likelihood of a proper fix. For warranty repairs the manufacturer usually wants the complete assembly replaced with a new one, again, to insure it's fixed properly.

Years isn't the issue. My '80 Volare and '93 Dynasty both have their original alternators but that's 45,000 and 4,200 miles. Regardless of your car's age, the 80,000 miles determines how much wear has taken place.

I CAN share that GM has had a really huge problem with their generators since they redesigned them in '87. It is very common to go through four to six of them in the life of the vehicle. Chrysler's are known for worn brushes on their Nippendenso made-in-Japan alternators. Repairs can often be done without removing them from the engine and the parts costs less than ten bucks. I have never heard of any such common history with Hyundai's generators, but if it quits completely at times, brushes are the most likely suspect. There are other ways generators can fail that aren't so obvious. When one of the six diodes shorts, two thirds of the output capability is lost. That means a common 90 amp generator will only be able to produce about 30 amps. That's barely enough to run the fuel pump, ignition system, head lights, and radio with nothing left over to recharge the battery. That IS enough to keep the warning light off so often you don't even know there's a problem.

To answer your question a different way, a generator on one car might last the entire life of the car while the same model on someone else's car might give up at less than 50,000 miles. Other than the 100 percent failure rate of the GM generators, there's no way to know how long one will last. Needing a replacement is not uncommon on any car.