I'm a dewalt man myself and I can share batteries between drills but they are all basically the same model so that's no surprise. I recently bought a top of the line dewalt self-levelling rotating laser lever which was described as accepting any 9.6v-18v dewalt battery and sure enough, it does......... almost......
Santa brought me an impressive new toy in the shape of a commercial grade (all metal transmission) 18v Li-ion dewalt drill and it has a totally different style and fitting for its battery which won't go in the previous drills or the laser level either.
