Single Battery Capacity: 1950mAh Charging time: about2 hours Operation time: about 6-7 hours Output Voltage : 5V-12V LCD display content: output voltage range + battery usage Instructions for use: - Power ON/OFF: Long press "O" key for 3 seconds - Output pause / resume: Short press "O" key to pause the output, and short press it again to resume the output(the resume voltage is the working voltage before the pause). - Adjust output voltage: Press the "+" or"-" key to adjust output voltage. The voltage can be adjusted through button (+) and (-) respectively with the voltage of 0.1V on each press. When you long press the voltage adjustment buttons, the voltage will change by 0.5V each time. Tattoo Power Supply: The LED display will show the remaining power, and the full power will display 4 divisions. Fast charging through the matching fast-charging USB data cable can usually be fully charged about 2 hours.