Have to you had to go through 1 or 2 alternators before you've gotten to a good one?

That happens a lot.

Some are legitimately defective. Shopping the lowest price will find the lowest quality... you know, you get what you pay for.

However, some are actually due to the battery. One common scenario goes like this.... alternator quit and the driver drives the vehicle until they get home or it leaves them on the side of the road, whichever comes first. The battery is either stone dead at this point, or very weak.

They buy an alternator, fire it up and the alternator is now having to charge the battery... at full output. Alternators are rated at various peak amp output... it may be 100 amps, 130amps, ect. This is a peak output, not a continuous duty output. Charging at peak output creates a huge amount of heat in the alternator. Its one thing to peak every now and then for a few seconds at a time, but to run steady at peak output for several minutes, even hours (added up over the different drive cycles the car goes through over several days time), the otherwise good alternator is burned out.

After the second or 3 rd alternator, the battery may have been charged up enough (assuming they didn't drive until dead this time), that the 2nd or 3rd alternator lasts.

So charge the battery, or even replace it, when you need a new alternator. That may save you some headache.