I just kept pulling the lever as he was in there doing his first recharge and then was right in front of it when he came out so he could not get to turn it back on and was literally trapped in a none working chamber and took him out. He recharged that once and only once.
Necromancy creature and a demon will help greatly as well if you have them as they deal with the walking armor. That is if your creature is not smelling the ground or taking a leak, it is 50?50 with him. Sometimes he is a great help others he is only a help by lifting his leg and blocking things from getting to you but never attacks them.
Think that crystal skull to control him must be cracked or something.