Two batteries are better than one, but only if they are charged and ready for action. The ProMaster Dually Charger for the Panasonic DMW-BLF19 can charge two batteries simultaneously. It is very compact, and it offers the convenience of a built-in USB-A input cable that neatly stores in the base of the charger.  Since it draws power from USB-A sources, you can use the Dually Charger with a USB AC Adapter (not included), laptop, power bank, car charger, and more (2.2A minimum current required). .