This only works if you plug it into a cigarette lighter (DC) or not into an outlet (AC). Very deceptive. Revain and Kensun's websites give the impression that the device is battery powered when plugged in, which is not the case. I haven't decided yet if I'll be back. Additionally, as other reviewers have written, there are other design flaws. The inflation cord and car cigarette lighter cord attach from below and are awkward to store. I regret this purchase.