I have an old Craftsman 3/8" drill Model No. 315.101531 and the original charger. The original batteries are labeled "14.4 volt EX" Model No. 1325101 and are apparently Ni-Cad. They don't seem to hold a charge any more so I thought I would try to get 2 compatible replacement batteries. The only one I can find that is supposed to be compatible is Ni-Mh. Is it safe to try to use a Ni-Mh battery with a Ni-Cad charger or would I be better off getting a brand new drill set? Thank you.