With proliferation of smartphones and tablets, we are connected online 24×7 as long as the devices have power. Due to bluetooth, wifi connections and various smartphone apps, smartphone batteries may drain mid-day and require a charge. We are not always near the wall outlet, and power banks come to rescue when we are on the road. There are so many different brands, types and sizes of power banks with various features. How do we find the one that is suitable for your need, and what do you look for when finding a good power bank?

1. Capacity in mAh – Bigger the better!

Power Banks use a battery to hold charges, and transfer that energy down to smartphone or tablet battery when connected. The battery capacity measured in mAh stands for milli-ampere-hour, which is a measurement of the amount of energy a battery can store. The one with 3200 mAh can store double the amount of energy than the one with 1600 mAh battery.
You’ll need a power bank with at least same size battery cell as your smartphone to complete a one full charge. Doubled cell size on power bank doesn’t necessarily translate to two full charge as there are other variables associated with the energy stored in battery cells. Both Power Bank and Smartphone batteries lose storage capacity over time after multiple charges.

Aside from capacity, a power bank’s output voltage must be greater than the charging device. Otherwise, the device won’t be charged.

2. Ampere Output – Bigger the faster!

Tablets require more energy to charge, so the power banks with higher Ampere output is needed to charge tablets.

3. Number of output USB Ports – More the better!

Most low capacity power banks come with only 1 USB output port. The larger capacity power banks may come with 2 or more USB ports at higher Ampere output for multiple devices.

4. Type and Quality of battery used in Power Bank – Lithium-Polymer is better!

There are two types of batteries used in power banks: Lithium-Polymer (Li-Po) and Lithium-Ion (Li-Ion). Li-Ion is more common as it has a higher energy density, but has in aging issue which causes to lose capacity over time. Li-Po on the other hand has a lower energy density and higher cost to manufacture, but do not suffer aging as much as Li-Ion and safer from explosion.
Most users will recharge their power bank unattended and extended period of time causing the power bank to be overcharged. Low grade battery cells used in power banks can be explosive, so high-grade Lithium-Polymer batteries are preferred.

 

FAQ:

1. Why is it take longer to charge a smartphone from a computer USB port than the USB wall charger?

Even though computer USB port and USB Wall charger both output 5V, USB port (USB 2.0) connection from a computer supplies only 0.5 amps as compared to 1-2 Amps from USB Wall charger. The performance of a power bank is somewhere in between, generally 5V/1A.

2. Can I use same charge port on power bank to charge different brands of batteries such as Apple, LG, Samsung and HTC?

Generally, you should be able to but not always. Depending on the built quality of the PCB used in the power banks, it may take longer to charge one brand battery over another.