<P> Due to its general purpose, powerbanks are also gaining popularity as a branding and promotional tool . Different brands and promotional companies use it as a promotional tool and provide a customized product . </P> <P> Some small lithium ion battery chargers for cells like 18650s and 26650s have the ability to be used as a powerbank when supplied with a charged cell and disconnected from a power source . However, not all of these chargers allow the battery to be charged from a USB source like a conventional powerbank . Although it is generally more cumbersome to carry such a charger with cells rather than a conventional powerbank, this type of setup has the advantage of being able to charge cells for other uses . It also has the advantage that, when the cell (s) is dead, it can be swapped for a fresh cell (s) for immediate use rather than having to be recharged before use . </P> <Ul> <Li> Capacity in Wh: Total power capacity measured by multiplying mAh by voltage . </Li> <Li> Capacity in mAh: mAh stands for milli Ampere - hour and measures the amount of power flow that can be supplied by a certain powerbank at a specific voltage . Many manufacturers rate their products at 3.7 V, the voltage of cell (s) inside . Since USB outputs at 5 V, calculations at this voltage will yield a lower mAh number . For example, a battery pack advertised with a 3000 mAh capacity (at 3.7 V) will produce 2220 mAh at 5 V. Power losses due to efficiency of the charging circuitry also occur . </Li> <Li> Simultaneous charging and discharging: need to specify if the powerbank can be used while it is charging . </Li> <Li> Number of output USB ports: This specifies the number of devices that can be charged simultaneously . </Li> <Li> Output current rating: This specifies the current rating that it can charge maximum . The higher the number, the better the powerbank . This can vary from output port to output port . Also, some powerbanks don't have dedicated high current ports, but will drop the output at all ports if the maximum total current output of the powerbank is exceeded . </Li> <Li> Input Current Rating: Input current rating is the amount of current the powerbank is able to draw at its maximum level while getting charged . </Li> <Li> Safety Protections: Over Voltage Protection, Over Charge Protections, Over Current Protections, Over Heat Protections, Short - Circuit Protections and Over Discharge Protections are the common safety measures observed with standard powerbanks . </Li> <Li> LED Indications: The Led glows as per indicating the amount of charging ability left with the powerbank . Some powerbanks have a line of LEDs, with the number of LEDs lit indicating state of charge . Other powerbanks may simply have one LED which changes color or flashes when the charge of the internal battery is low . </Li> </Ul> <Li> Capacity in Wh: Total power capacity measured by multiplying mAh by voltage . </Li>

What is the output of a mobile charger