Mobile Spec MS20W 20-Watt DC to AC Power Inverter with USB Input Power AC and USB devices in your vehicle, 20 watts of power Run and charge iPods, MP3 players, cell phones and more LED power indicator, dual spring contacts for maximum conductivity Input voltage range: 11-15 volt, maximum continuous wattage: 20 watt Low battery shutdown voltage: 10 volt  0.3 volt, high battery shutdown voltage: 15-16 volt