When our smart phone almost runs out of power, it is often USB portable power bank which we would rely on. Therefore, how to buy a good power bank battery backup becomes very important.
If the smart phone battery almost runs out, while we can not find the socket in sight, the battery pack can come out as a savior. The USB portable power bank, which can store energy, can not only charge the smart phone, but also supply power to Bluetooth devices, MP3 players and digital camera. Of course, the price of battery bank is not low. In the European market, the price of a charging bank can be around 5 Euros to 40 Euros. Of course we can not always measure the product by price. Expensive is not always equal to good quality.
First, about its capacity: it can be calculate by mA / hour (mAh), the same as the smart phone battery, it can also be measured by watts (Wh). The USB portable power bank whose maximum battery capacity is 3000mAh can easily and perfectly charge a smart phone. The charging bank whose maximum power is 6000mAh can charge two smart phones. Battery banks also have different sizes, and it’s suitable to be put in pants or jacket pockets. Generally they are really light. And cell phone power bank whose capacity is 10000mAh is very heavy. If you want to put them in the pants or jacket, it would bring much trouble, but they can charge for a number of mobile phones. Of course, they have to accumulate power for a whole week.
However, some of the manufacturer's instructions are wrong, because not all the power inside the battery can be charged into the smart phone. Rated capacity is not equal to the actual available capacity. In the process of power storage, there will be part of the electricity getting lost. For example, if the capacity of the USB portable power bank is 5000mAh. Now there is a smart phone, of which the capacity is 2500mAh, that needs to be charged. Then the battery bank can not fully charge two smart phones. As a reference, generally we can calculate the actual power consumption of this charging bank by subtracting 30% capacity declared in the manufacturer's instructions.
In addition, the capacity does not mean everything. The current is equally important to the capacity. Its unit is Ampere (A). The higher the input and output are, the faster the current flows. The current of the less expensive powers is generally 1A. That of the chip or fast charger could be as high as 2.1A. Therefore the USB portable power bank should ensure that the charging current is stable. IMPORTANT: To charge the tablet, the current must be sufficient, 1A is far from enough. So we prefer to buy charging bank of which the current is 1.5A or above 1.5A. The faster the current is, the easier it would be to protect the smart phone.
In addition, about the device. Different power banks have significantly different external facilities as well. If you want to charge more than one device at the same time, you would need a lot of USB ports. So a good power bank should have two or more interfaces. Some devices use a Micro-USB interface and together with a charging cable; some devices also have a lightning-fitted adapter for Apple devices. What’s more, LED display screen is also very important, as it can show the state of charging. Because if we charge a smart phone in a powerless USB portable power bank, and we do not detect, this situation would be quite embarrassing.