Choosing the right power bank for your device

Mobile devices have come a long way in the last several years. With all the goodies, such as extra processing power, better graphics, bigger screen and higher resolution, faster 3G/4G technology, better camera resolution and quality, and prettier appearance, the devices’ batteries get overwhelmed.

To meet the need for recharging these devices when a wall outlet is not convenient, a growing choice of the power bank (also called external battery pack, portable battery charger, external back-up battery, external battery charger, portable battery charger, power bank charger, portable power bank) has been manufactured.

Power banks are loaded with electrical energy which can power your digital device — such as smart phone, iPhone, MP3, MP4, camera, GPS and so on — anywhere and any time, which makes your outdoor activities and travel more flexible and more convenient.

It gives you the extended battery life whenever and wherever you need it while travelling on the road for many hours, relaxing on the beach or in preparation for those long hours of power rationing.

Many phone and tablet users find out that it’s not so easy to choose the right external battery for their gadget.

There are many dissatisfied customers who have bought these power banks, which either fail to work or stopped functioning just a few weeks later.

There are two types of battery cores in the power bank market: lithium polymer battery and 18650 lithium battery.

SAFETY AND CAPACITY

The lithium polymer battery is packed with aluminum-plastic; it’s light in weight and is always used in high-end electronics, such as the ultrathin power bank, cell phone battery and camera battery. The safety performance is better, and the storage capacity is larger than the lithium battery, but the price is higher too.

The 18650 battery core is cylindroid; 18650 means that the diameter is 18mm, and the length is 65mm.

Because of the fixed shape, the power bank with 18650 lithium battery is thicker. Nowadays, the technology of lithium battery has become mature, so the safety performance is good too.

DRAIN BATTERY

One key consideration is that the power output of the charger must be greater than or equal to the battery rating of your electronic device. If it’s not, the charger may drain your device’s battery. That’s right, the wrong charger can actually drain your device’s battery instead of charging it!

Most electronic devices that can be charged via a computer USB cable need a charging source with a 5V output rating.

How do you find the DC input rating for your electronic device? Two ways: You can look in your owner’s manual under technical specifications, or look for the voltage rating printed or stamped as “DC output” on the wall outlet charger that you likely got with your device.

Then make sure your portable power supply — which is expressed in milliAmps (mA) and volts (V) — can deliver at least the same amount.

Also note that battery chargers are not 100 per cent electricity efficient. The actual power discharged from a power bank is affected by temperature, voltage fluctuations and discharge rate. Thus, a power pack rated at 2000 mAh is unlikely to fully recharge a 1000 mAh electronic battery twice.

However, knowing the storage capacity of your device’s batteries does give you a good approximation of how many recharges to expect from your power pack.

Battery chargers offer a supplement, not a guarantee. Do not assume that these products will bring your device’s battery up to a full charge.

Customers report better success by doing a top-off recharge long before their device’s battery is fully discharged.

Generally, you cannot recharge your electronic device while the power pack is being charged. In some cases however, a solar charger does not contain an internal power pack and charges your device directly as it receives solar energy.

Sam Wambugu is a monitoring and evaluation specialist. Email: [email protected]