Mobile 12V source

For years, I used sealed lead acid batteries when I needed a current bush for my field research projects.  They were easy to carry in my pack and never leaked acid.   The shift to 20V power tools means I now have ready access to compact lithium batteries.    

A 12 volt transformer (DC 24V to 12V 10A 120W Step Down Converter Voltage Regulator Buck Power Converter Waterproof Transformer Module) with a Power Wheel Adapter Battery Adapter for Black and Decker 20V MAX Lithium Battery was attached to a small scrap of wood.  It allows the 20 volt batteries used for my Black and Decker tools to power 12V equipment.