Ford Bronco Alternator 2

Someone knows what are the tests that are done to the alternator of a Ford Bronco 2, it gives me 13.4 volts out of exit but noi is enough to keep the battery loaded after one use of more than half an hour if I turn off the truck after a couple of minutes I want to turn on it is made the battery and it has no strength for the start.

That alternator load is enough to load the battery, the problem can settle in the battery itself, put a tester in the battery and ask someone to contact you and star if the battery lowers to less than 11 or 10 volts is badly agreed, if it does not do the problem it can be the start.