Battery Light

My 02 Safari just lost power on the interstate without any prior warning. I saw the battery light appear as I pulled over to the shoulder. I shut off my a/c and daylights and the battery light disappeared, the engine was still running when I came to a stop and I proceeded without incedent. I have kept am eye on the voltometer which stays between 11-14 but will stay around the 11 mark when I engage the ac. My question is this: Is my alternator asking to be changed? In the past my experience has been either the alternators are among the living or among the dead???

i'd have alt and battery checked you can get it done free at auto zone or advanced if you have one around? also make sure your cables are clean. but sounds like alt.