Customers often call to report their alternator is "hot" or "too hot to touch" and are alarmed. In truth, work (amperage) = heat and this is normal. What is not normal, is a cold alternator! Under normal use an alternator can run between 180 and 250 degrees, keep in mind, the engine itself can be around 200 so it would be weird if the alternator was cold. This short video shows how quickly heat will rise with increased load

Watch IT HERE