Here's an interesting bit from an article I found:

It's really rare to see a charge indicator light fail on the dashboard. But if it does happen and you don't have a resistor in parallel with the charge indicator light, you can end up with an alternator that won't charge. This can be really frustrating for the vehicle owner. In such a situation, the vehicle's owner will have their car towed to a repair shop, the repair shop will note that the alternator isn't charging after charging the battery with an external charger enough to start the car and then connecting a voltmeter to the battery terminals while the car is running. The repair shop will replace your alternator only to find the new alternator still doesn't charge. So the repair shop will likely figure that they just got a "bad" alternator and have the parts store send over another alternator to install. But after installing the second alternator, the repair shop will find the charging system still doesn't work right. Maybe the repair shop will request another alternator from the parts store at this point, or maybe they'll suspect that something is wrong with the vehicle's electrical harness and start troubleshooting your car's electrical harness. Either way, you can end up with your car off the road for a while and incur significant labor costs over a two dollar light bulb.

It's silly that a simple lightbulb failure could cascade into a paralyzing situation.

Also, It's a little frustrating seeing how the conspicuous three terminal connector does not have a standard relating the function of its pins. It changes from brand to brand and even between models.

 

At least one automaker from NON-USA has been noted to change the commonly replaced parts every year so as to be able to keep aftermarket suppliers out of the competition.

 

It's silly that a simple lightbulb failure could cascade into a paralyzing situation.

Also, It's a little frustrating seeing how the conspicuous three terminal connector does not have a standard relating the function of its pins. It changes from brand to brand and even between models.

A good mechanic should spot that light though and be able to sort it out quickly... it should turn on when you first turn on the key. I have also seem times when "experienced" mechanics failed to notice the check engine light didn't come on when it was supposed to when first turning the key on and spending 8 hours looking in the wrong place. What was even more annoying was the fact that I told them that very fact before leaving work that morning.

It's one of those problems that will separate a mechanic from a parts changer.

Anyways...

About the only alternators I have dealt with that are pretty much the same through the years are the Delco SI series normally found on GM vehicles, (but they're in a lot of other things too). Some only need a battery connection. Most of them have a light connection and battery sense, but normally they'll work with just a battery connection. You may have to rev the engine up a little more before they'll start making power. In the older days that wasn't as much of an issue as it would be today.

 

The MOPAR alternators used a separate regulator, with the first few years using a single coil mechanical relay. Quite reliable and even at idle they would charge the BATTERY. Then they went to an electronic regulator that was fine until one of the field leads came loose, which destroyed the regulator. Then the design changed and one brush was grounded. The brushes would last but the bearings did not last. A separate regulator is the way to go, when it fails the replacement costs a lot less than even a rebuilt alternator.

 

On the history of regulators, the first were relay based, they then developed a Solid state version of it, the problem was that they produced a lot of radio interference, so the final result was the PWM version.