Power banks are popular for chargingsmartphonesandmobile tablet devices. A power bank is a portable device that can supply power from its built-in batteries through a USB port. They usually recharge withUSB power supply. Technically, a power bank consists of rechargeableLithium-ionorLithium-Polymerbatteries installed in a protective casing, guided by aprinted circuit board (PCB)which provides various protective and safety measures. Due to its general purpose, power banks 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.
Many power banks use the common 18650 sizelithium-ion batterywhich may or may not be user-replaceable.
Capacity in Wh: Total power capacity measured by multiplying mAh by voltage.
Capacity in mAh: mAhstands for Milli Ampere-hour and measures the amount of power flow that can be supplied by a certain power bank 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 the efficiency of the charging circuitry also occur.
Simultaneous charging and discharging: need to specify if the power bank can be used while it is charging.
The number of outputUSBports: This specifies the number of devices that can be charged simultaneously.
Output current rating: This specifies the current rating that it can charge maximum. The higher the number, the better the power bank. This can vary from output port to output port.
Input Current Rating: Input current rating is the amount of current the power bank is able to draw at its maximum level while getting charged.
Safety Protections: Over Voltage Protection, Over Charge Protection, Over Current Protection, Over Heat Protection, Short-Circuit Protections and Over Discharge Protections are the common safety measures observed with standard power banks.
LEDIndications: The Led glows as per indicating the amount of charging ability left with the power bank.