When you need to know that you’ll always have the charge you need, learn how to pick the best power bank.

For those of us who adore our mobile devices and who can’t live without our smartphones, there is nothing better than a fully charged battery, but if you’re always on the go, then there is no way to be certain that you’ll always have enough charge for everything that you need throughout the day unless you have an external battery pack on hand.

Of course, the popularity of these power banks have meant that there is no shortage of options from which to choose.

As with everything in life, all external battery pack devices are not created equal. For that reason, it is a good idea to learn a little bit about what these mobile phone chargers before you take out your wallet and make an actual purchase. That way, you’ll be able to know for certain that you have the right device to rebuild your charge even when you are unable to spend the next while attached to an AC outlet and would rather not bleed your laptop battery dry.

External battery pack smartphone chargers come in many shapes, sizes, and – of course – price tags.

Making the right choice of external battery charger will be worth every dollar you spend, but selecting the wrong option – even if it is exceptionally cheap – will only prove to be a waste of your money.

The main lesson that you need to understand has to do with the capacity of the mobile battery charger. It is usually represented in milliamperes (mAh). First, look at the capacity of your smartphone battery, then compare it to that of the power bank that you are considering for purchase. An iPhone 5 battery, for example, has a 1,440 mAh cell, whereas the Samsung Galaxy S3 has 2,100 mAh. With that information, you can then make sure that you are looking into a portable charger that will provide at least as much capacity as your cell phone when it is fully charge.

On the other hand, if you are always on the go or if you will be travelling and you will be bringing your smartphone, as well as your tablet and possibly your Bluetooth earpiece, then you’ll need to consider the capacity of all of those devices and make sure that your external battery pack can hold enough juice for all of them. The lesson: always know what devices you will be charging and choose a backup battery that has enough capacity for your needs.