Daniel Haaf
Prisjakt
Updated: 20 May 2026
With a power bank you can charge both mobile phones and other battery-powered devices away from home. Choosing the right one can be a bit tricky because you need to consider a range of technical aspects. Here we have broken down the decision process into six clear steps to help you along the way.
The first step is to find out how much charge the battery in your mobile phone can hold. Battery capacity is measured in milliampere-hours, abbreviated mAh. So you need to find out how many milliampere-hours the battery in your mobile phone contains.
This information is usually printed on the battery, but if you cannot access the battery you can google the figure. You can also search for your mobile phone on Prisjakt, where the information is listed among the specifications.
If you choose a slightly more expensive powerbank that can also charge laptops you should opt for a model with as high a capacity as possible.
Image: Photo: Unsplash, Reka Sarudi
The second step is to decide how many times you want to charge your mobile phone. At least two charges are recommended for those who commute often or travel a lot.
When you use a powerbank some of the charge is lost as heat. Allow for around one third of the total capacity being lost on less efficient models. So if you want to charge a Huawei P20, which holds 3,400 milliampere-hours, fully twice, you need a powerbank of around 10,000 milliampere-hours.
Bear in mind that more milliampere-hours almost always means a physically larger powerbank. If you have limited space in, for example, your bag or jacket, a smaller model will of course work.
Now we have established how much charge you need. The next step is to find out how quickly you want it transferred from the powerbank to your mobile phone. This is called current and is measured in amperes, abbreviated A.
It doesn't really matter how many amperes the phone and the powerbank have – the phone's battery will charge regardless. What differs is how fast it happens.
If you want the charging to be as fast as possible the powerbank should be able to provide at least as many amperes as your mobile phone can accept. Newer phones almost always handle just over 2.0 amperes, but if you want to be sure you can usually find the information on the manufacturer's website.
The charger for the Samsung Galaxy S9 has a maximum current of 2.0 amperes. If you buy a powerbank that can only provide 1.0 ampere, charging will take twice as long compared with one that can provide 2.0 amperes.
You never need to worry about the powerbank providing more amperes than the phone can accept, because the phone will only draw as many amperes as it needs.
Image: Photo: Unsplash, Markus Winkler
Earlier we looked at how fast the powerbank can charge a mobile phone. In this section we look at how fast the powerbank can charge itself, the so-called input current.
This is especially important to consider if you are looking for larger powerbanks that hold up to around 10,000 milliampere-hours. With a low input current they can otherwise take up to half a day to charge. A powerbank with an input current of 1.0 ampere will take twice as long to charge as one with 2.0 amperes.
To find out how many input amperes a powerbank has you can check the manufacturer's or the retailer's website.
Keep in mind that sometimes a charger or charging cable is not included with the powerbank. In many cases the manufacturer assumes you already have a charger and USB cable at home. Many old chargers provide only 1.0 ampere. That means a powerbank with an input current of 2.0 amperes can only charge at half speed. Newer battery chargers often handle 2.0 amperes or more, which enables full charging speed for the powerbank.
If you connect the powerbank to your computer via USB, a USB 3.0 port can provide 0.9 ampere.
Image: Photo: Unsplash, Markus Winkler
Many powerbanks have several different ports. The most common are ordinary USB ports, which fit most devices. Recently USB-C ports have also started to appear, which suit, for example, Apple's newest computers. They can provide higher charging speeds.
Check that what you intend to charge can be physically connected to the powerbank. Also consider how many ports you need. And when you do that, take another look at the ampere issue.
Not all ports on a powerbank necessarily provide the same number of amperes. It is also not guaranteed that you can run the maximum number of amperes on all ports at the same time, because the battery may have a lower total current. A powerbank with three ports of 2.0 amperes each may, for example, have a total output of 4.0 amperes. Then you will get at most 4.0 amperes in total, regardless of how you use it.
There are powerbanks with special functions. One may be that they are equipped with a solar panel, which makes you independent of wall sockets as long as the weather is fine. Another may be that the powerbank actually consists of ordinary, rechargeable batteries that you can replace.
A feature worth giving extra thought to is the indicator that shows how much charge remains. It can consist of a small number of lights or a more precise display. In some cases there is no indicator at all, which makes it difficult to estimate when the battery is empty.
In some cases the powerbank is equipped with a torch or a weatherproof casing. Sometimes cables or a case are included.