prices on 2 models
Battery
— the presence of a battery allows the device to work independently of any external energy sources, however, the period of such work is limited, and sooner or later you still have to take a break to charge the battery. Therefore, this type of power supply is extremely rare in its pure form — much more often the battery is provided as a “fallback option” that complements power from the mains or USB (see the relevant paragraphs).