stock alternator burns brushes

Oh yeah , tested battery the old way(toaster) holds 800amp for over 20 secs. Electronic tester doesn t detect any flaws (dead cells , reverse polarity...). Also batt will run without alternator for about an hour and still start(weak but itll start), this batt came with the car has a 2015 date on it and I must say one of the best batteries I ve ever had(duralast gold gr24 750cca, don t work for them never even seen that brand in canada(car bought in U.S.)just like to say it when someone has a good product).