Amazon.com: Fancy Buying Replacement Battery Adapter DCA1820 for Dewalt 18V Tools, Convert 18V / 20V Lithium Battery to NiCad/NiMH Battery, Makes The Battery can be Used for Nickel Drill and Charger :
DEWALT 20V MAX Lithium-Ion Battery Adapter for 18V Tools DCA1820 - The Home Depot