I recently purchased the 12v drill and the 3 piece 18v combo kit. Question. Can the 12v batteries be charged with the charger contained in the 18 v kit, and vice versa. The 12v charger is a 20 minuute charger vs the 30 minute dual charger in the kit. I asked the guy at HD and he said there was no problem, but not sure if he understood my question. Need some help and glad to have this forum available. Thanks for your help.