25000 mAh 25000 mAh Portable Power Bank 25 watt Grey/White

OverviewA power or battery bank is a portable device that can supply energy and power from its built-in battery, typically through a USB port.Power banks have various sizes and typically contain 18650 battery cells. The smallest power banks have a single cell. Moderately sized ones for mobile phones usually have few cells in a parallel circuit, and large ones additionally in two series.Power banks are popular for charging smaller battery-powered devices with USB ports such as mobile phones and tablet computers and can be used as a power supply for various USB-powered accessories such as lights, small fans and external digital camera battery chargers. They usually recharge with a USB power supply. More recent power banks use USB-C and may feature an additional USB-B micro port for backwards compatibility.The power bank includes a control circuit that both regulates charging of the battery and converts the battery voltage to 5.0 volts for the USB port.[citation needed] Power banks may be able to detect a connection and power on automatically. If the current load is under a model-specific threshold for a specific duration, a power bank may power down automatically.Charging state is typically indicated through four LED lamps for each quartal, whereas some higher-end models feature an exact percentage display.Some power banks are able to deliver power wirelessly, some are equipped with an LED flashlight for casual near-distance illumination when necessary, and some have a pass-through charging feature which allows providing power through their USB ports while being charged themselves simultaneously.Some larger power banks have DC connector (or barrel connector) for higher power demands such as laptop computers.