Nothing wrong with aluminium as a conductor. Its cheaper and lighter than copper and is what overhead power lines are made from. As has been stated, the oxidising or anodising (2 different things) layer makes getting a good contact difficult. The way to get through the layer is to scrape it off with a file, sandpaper, steel wool etc and all will be well. watch for corrosion in that area though.
A point on batteries. A cooked regulator will deliver whatever voltage it likes to a battery regardless of what state the battery is in.The battery will not regulate the voltage, only smooth out the ripples. A good battery will soon be turned into a bad battery by a regulator pumping 18 volts into it and boiling it dry with obvious results. Suzuki motorcycles were GREAT at doing this...ask me how I know.....:yuk:.
Phil