Become the essential companion of very many smartphones, the external battery allows to extend the autonomy of Android devices at low cost. But how to find your way among the countless references available on the net. Here is our selection to guide you in the purchase of an external battery..
The battery of your smartphone runs out too quickly
We can do whatever it takes to reduce the energy consumption of our mobile phone, sometimes it is not enough to last an entire day on a single charge. If you are a big consumer of social networks or apps using GPS, you have already noticed that the autonomy of Android smartphones leaves something to be desired.
Reducing the screen brightness, cutting wireless connections, canceling automatic synchronization of accounts or activating the energy saver allow you to save a few tens of minutes or even a few hours of additional autonomy. Only here, we should not expect miracles either..
It is obvious, the more you use your smartphone and the more the battery drains. If you are among those who spend hours on the mobile web watching videos or checking their messages, you might want to consider investing in an external battery .
What is an external battery
The external battery is in the form of a small, relatively compact plastic housing equipped with one or two USB outputs. Compatible with the vast majority of Android smartphones and tablets, these portable chargers appeal to professionals as well as individuals. The only problem is that not all models are created equal..
No question therefore of committing in a hurry, you may regret it. The purchase of a nomadic accumulator must respond to a rigorous selection. Charging time , actual capacity, output current are all points to check.
How to choose an external battery?
First criterion to take into account, the actual capacity expressed in milliampere hours. The latter must be absolutely higher than that of the battery fitted to your smartphone.
Concretely, if the battery of your mobile has a capacity of 2500 mAh, you will have to opt for a portable charger of at least 3400 mAh (energy loss). If you choose an external battery with a lower capacity, you will not be able to fully charge your smartphone.
It may seem obvious but it must still be specified. The larger the capacity, the more cumbersome the external battery will be. It is therefore an important criterion especially if you intended to always travel with your mobile charger.
Finally, last important point, some manufacturers have taken the bad habit of artificially inflating the capacities of their pocket batteries. Read the labels carefully and pay attention to the prices. Ultra-flat 20,000 mAh batteries, sold for barely ten euros, necessarily hide something.
Nomadic battery recharging speed
Particular attention should also be paid to the charging time of the external battery. We sometimes forget it but it must be regularly plugged into an electrical outlet. Some models also have indicators allowing to know precisely its charge level. Prefer nomad chargers supporting 1A input. It will charge it faster.
Having a large capacity battery is good, but it still needs to be able to charge your device at high speed. Smartphones generally demand a power of around 1A. For tablets or mobiles equipped with a very large screen, opt for an output intensity of 2A.
What you must remember
In terms of external battery, there is everything. As always, favor brands with a storefront and avoid overly attractive offers. There are a lot of counterfeit batteries on the net. Similarly, some nomadic chargers offer results far removed from the figures provided by their manufacturer.
Our selection of external battery
We begin this selection with a model from the American manufacturer PNY.
PNY PowerPack T10400
The PowerPack battery has a capacity of 10400 mAh and a series of 6 LEDs to know precisely the remaining charge. It will allow you to carry out four full recharges of a smartphone. 
Sony CP-V5
The Japanese giant's battery uses lithium-polymer technology. More expensive than lithium-ion , it offers a higher energy density and better resistance to aging. With its 5000 mAh, its high-end finish and its great robustness, the Sony CP-V5 displays good value for money. 
Tecknet PowerZen 16750 mAh
The Tecknet PowerZen battery offers the largest capacity of this selection. With 16750 mAh it offers almost 7 days of charge to your mobile. Side size unnecessary to expect a miracle. The case turns out to be rather bulky. Impossible for example to store it in a pants pocket. But if we compare it to its real capacity, the size is still very acceptable.
The PowerZen has two USB ports for recharging two devices at the same time. These are capable of detecting the type of phone connected in order to optimize the speed of supply and obtain the shortest charging time. 