The device itself is an absolute dream compared to a TomTom is but absolutely devalued by the battery quality. I myself have 2x the unit exchanged because I thought the poor battery quality is a blip, but the service of Becker wrote me it was all right. I have charged the unit, it was back on the next day - went but not because of empty battery the device abschaltete automatically after 10 seconds. Ergo, it may be suitable for direct connection to the car battery, but as soon as I want it to act independently, it is no longer possible. Schade