I modified a DeWalt battery charger to have the battery act as a power supply for a 12V car charger so I can charge my phone and radio on my work cart.
Amazon.com: LALAFO DCB119 Car Charger Replacement for Dewalt 12V/20V Max Lithium-ion Battery Charger DCB107 DCB112 DCB115 DCB118, Compatible with Dewalt 12V 20V Max Li-ion Batteries DCB124 DCB205 DCB240 DCB606 : Tools &