How to choose your portable battery

External batteries are booming. Smartphones continue with terrible autonomy of one or, at most, two days at best, and almost without touching it. As manufacturers research technologies to evolve the energy factor, what solutions do we have?

Accessories like external batteries can give us that extra fundamental energy in many situations. They are perfect so that our smartphone continues to turn on after long trips or excursions where we will not have at our disposal a wall socket. What features are important in an external battery? What factors should be taken into account when choosing a good external battery? Both these and other questions will be discussed below.

Why have an external battery?

If we go back ten years in time, the autonomy of mobile phones was not a problem:at the time they offered one or even two weeks of autonomy, a period that in most cases was more than enough to be able to recharge it in some wall socket.

Since then things have changed a lot. The advent of smartphones has radically changed the way we enjoyed 'mobile',and since the first models back in 2007 and 2008 we were already beginning to intuit where this new category of technology was going to be routed: they usually last a day of use, and they are even a few hours with intensive use. Many of the smartphones also have a hard-to-replace built-in battery, so it can't be replaced to revitalize the device either.

One of the solutions the industry has come to is external batteries. It is not a novel or innovative invention, if not practical and functional with which to apply a patch to the problem: I wish smartphones had the autonomy of old mobile phones, but this possibility is not contemplated for the next few years.

External batteries function as a continent that stores energy. They recharge like smartphone batteries, then transmitthat contained power to the new stand.

It is important to mention that even if we are used to using them with our smartphones, they can also charge other devices (typically any that is charged via USB, such as tablets, e-book readers or cameras) and there are even more powerful models that can add charge to laptops.

If we focus on the most common ones, external smartphone batteries are usually small and relatively inexpensive. Small enough to be easily transportable, and at a cost it can range from a few euros to several tens. Depending on several factors, which we'll describe later, they can perform a fraction of a device's charge, an entire charge, or even several.

Features to keep in mind

The most common is to measure the capacity of external batteries in mAh., milli-amp hours,the same unit used in the internal batteries of smartphones. For many it is not the best measure of the 'charge' of a battery, but it must be said that it is the most widespread in the industry.

A practical example: if our smartphone has a 2,000 mAh battery, an external 2,000 mAh battery. would be able to perform a full charging cycle, that is, load it completely on the other hand on the that it is completely exhausted. There are certain details, such as losses caused by energy transmission or decreased capacity over time, which can be taken into account as lower impact factors, for many secondary.

As with chargers, there is an important feature: the intensity of thecurrent, measured in amps (A.) in the International System and intimately linked to the 'charging speed': the higher the amperage, the faster the battery will charge. We mean the output amperage of the external battery, which is the element from which the power "comes out" in the direction of the battery of the final device.

Amperage is important not only because of the 'speed' of charging: it can also be a problem, as excessive current intensity can damage batteries, either in the short term or in the long term. For reference, a smartphone wall charger usually offers around 1 A., depending on make and model. We should also mention that the greater the intensity with which a battery is charged, the less the battery's durability over time; in other words: the more 'slow' (less amperage) the process of charging a battery, the longer its lifespan.

In the world of external batteries the most common is that we find a microUSB input (to be able to charge it with the same charger as that of the smartphone) and a USB port that acts as an output. This USB port is where we will connect the plugged-in cable to our phone. This solution is universal, since all smartphones are charged from a USB cable, and that is why it is the best we can find.

There are other external batteries that provide an integrated cable that limits the possibilities. Some, in addition to this cable, also a USB port, so that they expand our fan again. microUSB is the most widely used charging standard, but not the only one on the market, and this is something to keep in mind as not all smartphones or tablets use it.

In addition to the load capacity and connectors, there are endless small details that we can take into account. Physical dimensions (lengths and also weight) of course, but also lights that determine the percentage of remaining load or manufacturing materials for the housing.

What external battery to buy?

Of course it is not an easy-to-answer question, as the existing variety of models is certainly wide.

Personally I would avoid 'unknown' brand batteries, or that support low quality product. As with chargers, it is important that the materials used in your manufacturing can properly withstand the passage of current, or else we may have problems that can even spoil the phone completely.

And what are the marks? Some well known (Energizer, Duracell, Sony), others that will sound to you (Mophie, Zag, HyperJuice) and many that is probably the first time you will read (Anker, PowerRocks, Tilt, Innergie, RAVPower...). As always, the Internet will be of great help to know how each of them works, although here we will offer you a trio of interesting models to get an idea of the price at which these accessories move:

• Anker Astro E5: 15,000 mAh. and dual USB port (5V/2A and 5V/1A), 39.99 euros on Amazon.

• RAVPower Deluxe: 8,400 mAh. and dual USB port ((5V/2A and 5V/1A), 21.99 euros on Amazon.

• Anker Astro Mini: 3,000 mAh., a USB port and LED flashlight, 19.99 euros on Amazon.

We have already mentioned that the ideal is to look for an external 'universal' battery, to which to connect a USB cable to our device. About which capacity is the best,this is a personal issue: it is not necessary to go to 'the highest capacity', as these are usually the largest and heaviest on the market. Depending on the phone model we have, covering one or two charge cycles may be ideal. There are some that even support charging multiple smartphones simultaneously, so in case this option interests us we will have to go to an external battery of greater capacity.

Last but not least, design can be a differentiating aspect. They are usually rectangular prisms, but there are also external cylinder-shaped batteries, cube batteries and even other rarities. If you play with the sizes you will even find keychains or batteries the size of a credit card, although in these two cases they are more decorative elements given their low capacity.

A more necessary accessory than ever

The evolution of two-week phones to smartphones with only one or two days of 'duration' was too fast. Many of us thought that manufacturers would bet on looking for techniques and technologies with which to expand the battery of their smartphones, but that has not even happened... there is no hope that it will happen in the coming years.

External batteries are an economical option and can be an acceptable solution to the problem of autonomy. An interesting accessory for times when we won't have a wall socket available for many hours, or even days, and we need the mobile phone. Hopefully manufacturers will improve battery technology (thereare some advances in this regard),in the meantime we can use the patch that external batteries are.