Two B&D 18v NiCad batteries. They both fit my old 18v B&D EPC18 drill, but only the 2-pin/prong A18E battery works. The 3-pin ML:HPB18 is completely dead in the drill, but, after testing, seems to be fully charged. So, could anyone clarify the difference between these two batteries - at least in terms of what tool the useless-to-me 3-prong one is intended for, to that i can offer it to someone who could maybe use it...?