External batteries, also known as “powerbanks,” have become one of the most popular accessories for smartphones. Although these increasingly offer more autonomy, as we verified in the collection of mobiles with more battery, on some occasions that extra energy is necessary when spending a lot of time away from home or when using the terminal heavily.

The market is full of different models of external batteries, so it can be somewhat difficult to choose the most suitable for your mobile. In order to help you choose, in this guide we are going to talk to you about The 5 things you should look at and analyze when buying an external battery or “powerbank”: capacity, size, price … Let’s go there!

What to look for when buying an external battery for your mobile


One of the main aspects to consider when buying an external battery is obviously its capacity. This is represented in milliamps per hour (mAh), which refer to the electrical charge that the battery is capable of storing. The more mAh the “powerbank” has, it is understood that the greater the energy and duration will be. In the market you can find a very wide range of storage capacity, for example, Xiaomi has 5,000, 10,000 or 20,000 mAh batteries in its catalog.

Unfortunately, the real capacity of the “powerbanks” It is far from the capacity reflected in those mAh, and you should also take this into account. The elements chosen for their manufacture and the efficiency of the electronic circuit directly affect the real capacity of the external battery, which usually remains in the 60% or 70% of the “official” capacity on most models. Whatever the battery, it will never be able to transfer 100% of its energy to the phone, as part of it will always be lost in the process.

Xiaomi is one of the brands specialized in external batteries

For example, if your mobile is 4,000 mAh and you choose an external 12,000 mAh battery, don’t expect it to be able to give you three full charges, because it won’t be. Regarding capacity, always opt for a “powerbank” that is sufficient for your phone, no more, because obviously its capacity will directly influence the price.

In addition, you should also know that the storage and transfer capacity of the external battery is diminishing with its use. You always can extend its useful life if you are careful during its use, avoiding connecting it to the mobile if it is very hot or always using quality chargers.

Input and output charging speed

Capacity is not the only thing that matters when choosing this accessory for your mobile, you must also take into account the time that you will need to charge the battery in question. For this you must look at the input speed, which is represented in volts and amperage as “5.0 V / 2 A”. This would mean the battery charges at 5 volts and 2 amps, enough so you don’t have to keep it connected to the charger for hours on end. The more current it accepts, the sooner it will be charged.

If the input speed is important, the output speed is even more important, the one that reflects what is the battery intensity when charging your mobile and other devices. In the information of the “powerbank” you can know what is the maximum amperage (A) that each of its ports can provide, although the final amperage of energy transfer will depend on the maximum that the device to be connected supports.

For example, if the external battery can charge a maximum of 2.1A, but your mobile only supports 1A, that will be the amperage that the battery will use. If you are looking for an external battery that will quickly charge the devices you connect, 5V.2A is more than adequate capacity.

Both input and output charging speed are key when choosing an external battery

By choosing “powerbank”, you can choose a model with intelligent charging system, which is responsible for optimizing the process when there are several devices connected to distribute the current and give each one of them the energy it needs.

In addition, in the current market you can find external batteries with fast charge that adapt to mobiles with this system. If you have a mobile with fast charge, do not hesitate to get a “powerbank” with the same feature to be able to charge it at maximum speed.

Types and numbers of cargo ports

So that the external battery can charge your mobile phone, what you must do is connect it to it. Therefore, you must take into account the connectivity section of the “powerbank” to avoid problems once you have already purchased it. First of all, you need to look at the number of outputs of the external battery, that is, how many ports do you have and thus how many devices can it power simultaneously.

Powerbank baseus ports

Powerbank with five devices connected to its charging ports

While looking at how many charging ports the accessory has, you should also look at what type of ports exactly. Most are standard USB, but there are also outputs with the standard USB Power Delivery, which ensure faster, faster and simultaneous charging for various devices.

For larger devices like laptops, you can search for external batteries with 9V / 12V DC ports, trained to transfer energy with maximum power and speed.

Design and size

You should not overlook the importance of the design, size and resistance of the external battery you are going to buy. As we mentioned before, the materials of the device are very relevant to the actual capacity of the device. Also, normally a more storage is synonymous with a bigger and heavier battery.

In the market you can find small models, similar to a lipstick, ideal to always carry them on. Faced with its easy transport, we find drawbacks such as its few charging ports or a limited capacity that usually does not exceed 5,000 or 6,000 mAh.

If you are looking for more storage, you have the option of external slim batteries, with a design similar to that of a smartphone. They are very thin devices that can also be transported comfortably and can reach 10,000 mAh. As we have explained, a battery with a greater capacity has increased its size significantly. In exchange for an energy storage of 15,000 or 20,000 mAh you will have to agree to carry a Much bigger and heavier brick-type powerbank than the other models.

20000 mAh Aukey external battery

Aukey external battery feeding its 20,000 mAh to a mobile

Finally, and with regard to the design of materials, we recall that there are environmentally friendly external batteries. So is GOMI, a portable battery that protects the planet being made with recycled products. Sounds like a good option, right?


All aspects mentioned so far directly influence the price of the external battery what are you going to buy. More capacity, more charging ports and greater power are the characteristics that you should look for in this accessory for your mobile, but always taking into account what are the specifications that you need and what is the investment that you can allow.

Always look for the best price, but without falling into the trap of possible manufacturers without quality that try to sell you external batteries of little use. To avoid these situations, we recommend buying devices from companies specialized in “powerbanks” like AUKEY, Belkin, ANKER or Xiaomi itself. Perhaps you will have to pay more than for those bargains that attract your attention, but you will surely be buying a quality external battery.

Find what you are looking for cheaper in our Chollos channel, and if you are still thinking about it, take a look at our other buying guides. The prices shown in this article are current at the time of publication, so it is possible that they vary depending on the stock and demand in the different sales channels.

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