Power ON/OFF No need to worry about the draining car battery anymore. Just long-press CH button for 2 sec to turn it on and long press for 3 sec to turn it off.\r\n \r\nStrong Compatibility Compatible with phones, tablets, and any Bluetooth-enabled devices, as well as cars, trucks, and other 12-24V vehicles.\r\n \r\nVoltage Detection With inserted voltage detecting chip, you can capture the voltage status of your car in real-time. 12 V indicates battery replacement needed. 12.0-12.8 V indicates the normal voltage if the car isn’t started. 13.0-14.8 V indicates the normal voltage if the car is started. (Note: If the voltage is under 12 V when the car is not started, please replace the battery as soon as possible.)