Charge and maintain battery properly. Teufel Support September 19, 2023 10:01 Updated How to properly charge and care for the battery so that the described service life and capacity remain unrestrictedly high can be found here: Battery care Related articles ROCKSTER / ROCKSTER AIR: The battery does not charge and/or discharges very quickly. Is this a defect? ROCKSTER XS: The charge level LEDs do not light up (sometimes). ROCKSTER AIR: Device not usable although switched on. The LEDs light up BOOMSTER (2020): What is the purpose of the battery switch on the back? ROCKSTER: Can the device also be operated from a car socket (12 V)?