This walk-through metal detector comes with power protection and a built-in battery that can last up to 8 hours when used continuously. Charging takes approximately 4 hours. It displays battery capacity in real-time, and low power is indicated by a power indicator light on the LED light. When the power indicator light flashes continually, it may work for around 10 minutes. When the power is turned on, it runs a self-diagnostic program that checks the left and right door panels, the LED light, and selects the best working frequency.