alternator questions

[bbob203]

so I killed my battery yesterday by leaving my climate control on when my car was off letting my fan run for awhile. got a jump off and away fast forward later in the day everywhere I go my car wont start have to get jumped etc. finally ended up being so dead my car wouldn't stay running got a tow home tow guy helped me figure it was the alt took it out had it tested. went home swapped out the brushes from another alt jumped it battery is charging alt is working great. Does more load on the alt cause the brushes to wear faster I'm guessing so? also one of my alts has a little black square with a single wire running to a terminal the other alt(the one I put brushes into that went on me) has never had one of these since I bought the car it came on. could the lack of this piece cause

[bajacalal]

More load on the brushes, I would think would cause them to heat up, reducing their life.

I think that thing is a capacitor to reduce electromagnetic interference from the alternator, that you would otherwise hear over the car's radio.