The Perun PB-23 640Wh battery back-up for the PB-20 600w portable power station doubles the runtime for extended power supply. This innovative battery back-up charges directly through the PB-20 so there is no complicated extra cables needed. Simply connect with the cable provided and charge with the same input power you are charging your PB-22: AC outlet, 12v or solar panels. This extended runtime combination is the optimum solution for continuous running power for your home, office and on-the-go. Keep them charged and ready for emergency power or take it with you to the park, camping or just in the backyard. If your job requires power in the field for computer, tablet, lighting, and other electronics the PB-20+PB-23 is the perfect solution! You can charge and operate as many as 9 different devices at the same time with the wide range of power output options. Charging is a breeze with 3 different options: wall outlet, 12v car plug or solar panel.