Smartphones have become so essential to us on a daily basis that we are ready to make some concessions to avoid running out of fuel while on the move. Like, for example, buying and keeping in your pocket an external battery that will bring our precious phone back to life when there is no power outlet nearby.
The autonomy of smartphones melting like snow in the sun – no longer a question of holding a week without recharging, as with a good old Nokia 3310… – these accessories have experienced significant growth, like that of mobile devices. However, not all models are equal, the price ranges are wide – from 10 to sometimes more than 100 euros – and the technical characteristics vary according to the devices to be recharged and the technologies used. Here are some tips for making the right choice.
The first is to opt for a brand that already has a few years of experience in the field. Players like Anker or RAVPower, for example, are specialists, as are smartphone manufacturers such as Xiaomi. Under the pretext of saving a few euros, it would be regrettable to buy a battery that does not respect safety standards which could damage your smartphone, or even cause an accident or a fire. The best brands systematically provide you with accurate information on the subject. Some even offer a low-power charging mode for small connected objects, such as watches or connected bracelets.
External batteries are chosen mainly on the basis of their capacity (expressed in mAh), their connectors (number and type of integrated ports for connecting a smartphone, tablet and other devices) and their power (from 15 W, a battery is powerful enough to offer fast charging to your mobile).
Before you start looking for a model, check the battery capacity of the devices you plan to charge. If your mobile is equipped with a 3,500 mAh battery, your external battery will need to be at least 5,000 mAh to fully charge it, due to energy losses associated with the very operation of this type of product. If you want to be perfectly autonomous for a few days or if you plan to charge different devices (mobile, tablet, mobile speaker, etc.), opt for a 10,000 mAh or even 20,000 mAh battery instead to have several charge cycles. Very high capacity models (above 25,000 mAh) can even charge laptops equipped with a USB-C port.
Also pay attention to the maximum current intensity available at the output, which is expressed in amperes (A) or milli-amperes (mA), because it must correspond to that recommended to correctly recharge a device. If some small objects – a connected watch, for example – can be satisfied with 500 mA (i.e. 0.5 A), others require 1 or 2 A. A battery offering only 3 A maximum output will not be able to suitably and simultaneously recharge two telephones each requiring 2 A.
In terms of connectivity, we often find batteries equipped with a micro-USB port intended to recharge them (more rarely with a Mini USB port, a sign that it is an old model) or a port Lightning for iPhone users. The micro-USB to USB cable is also often provided. Then comes a USB-A port, or even two or three to ensure the charging of several devices simultaneously. The most recent batteries (necessarily more expensive, but also more efficient) also benefit from a USB Type-C port which can be used both as an input and as an output (to charge the battery itself and all your mobile devices compatible: a USB-C laptop or a Google Pixel smartphone). Some rare battery models even offer one or two integrated cables (which saves you from lugging the cables of your devices, necessary for charging, in addition to the external battery).
As far as power and therefore speed are concerned, the bulk of the fleet of external batteries delivers a power of 10 W: a result obtained by multiplying the voltage (or voltage, by Anglicism) expressed in volts by the intensity expressed in amperes , usually 5 V x 2 A. This is what many phone chargers offer today. From 12 W, but especially from 15 or 18 W, we can speak of fast charging, or the possibility of fully recharging a device much more quickly. Via a USB type-C port, you can sometimes even get up to 45 W or more. However, the devices you want to charge must be compatible with fast charging. A vast subject to study before any purchase because there are many technologies, most of the time proprietary (Quick Charge, Power Delivery, etc.). If this is not the case, settle for a classic battery. Also be aware that if you connect several devices to your battery, its maximum power will be distributed between the different loads. It will therefore be… slower!
Finally, be aware that it sometimes takes between 5 and 10 hours to fully charge an external battery, provided it has a capacity of 10,000 or 20,000 mAh. If it offers a fast input charging function, you will save a lot of time, but you will need to purchase a suitable mains adapter, for example in 5 V 3 A or 9 V 2 A for a power of 15 to 18 W. For optimal operation, also be sure to use the cable supplied with your devices (smartphones, tablets) or to buy a certified cable (MFi for Apple Lightning cables, for example).
The dimensions and weight of an external battery are largely related to its capacity. A 5,000 mAh battery will easily fit in a pocket and will weigh no more than 150 g while a 20,000 to 30,000 mAh battery will need to be carried in a bag and will approach 500 g.
Their shape is most often that of a more or less thick block, but on models with a capacity of less than 10,000 mAh, we sometimes find a more original design of the tubular type. For the iPhone, there are also shell batteries, the Smart Battery Case, or dedicated batteries made by partners like Mophie – sold at exorbitant prices – and which can only be found in Apple Stores. It’s up to everyone to choose according to their budget and tastes.
A fairly basic device, the external battery evolves little – or at least very slowly – and is difficult to surprise. However, some manufacturers offer Qi-standard wireless external batteries to charge compatible smartphone models (iPhone, Samsung Galaxy, etc.). Going without a cord is convenient, but charging is slower and these models are more expensive. There are also solar batteries, but they struggle to seduce insofar as their recharge requires several days in direct sunlight. This can possibly constitute a complement in reinforcement of a more traditional mode of loading. Finally, some manufacturers have thought of associating pleasant, if not essential, functions with their products: a display to know the precise percentage of charge, an integrated base to take advantage of your smartphone in hands-free mode or even a flashlight to illuminate a lock at night. There are even hand warmers that also act as an external battery!