Indicator: Green-Operation, Red-Shutdown . Over Voltage Shutdown: DC15V-16V, Low Voltage Shutdown: DC10V-11V. Optimal Use and Precautions This product is for DC12V and Car ONLY, not applied for DC 24V and airplane use. For charging your iPad, please use the 2.1A USB port and keep the other USB port free. It’s normal for the inverter to become warm to the touch while you are using it, avoid placing the inverter in direct sunlight or next to heat-sensitive materials.