Portable device chargers are used to put energy into a battery, for use on the move. Portable device chargers are often designed to be used with multiple different devices, which is achieved by using a common connection such as a USB or micro USB port.
Portable device chargers are used to keep devices at full battery charge. They are particularly useful when you need to replenish the charge on a device when you are away from a mains plug.
Portable device chargers differ principally in the method of charging. The category includes car chargers and certain types of battery pack chargers that don't require a wall connection. They may vary in their type of output connector, whether USB, micro USB or different types of DC connector, and whether they are designed to be used as a stand-alone device or in car. Some portable device chargers offer more than one slot, to allow for the charging of multiple devices at once.