All smartphones, tablets, cameras and other gadgets have one thing in common: the battery runs out when you do not have a charger nearby. A powerbank can be a solution in those cases. A portable battery makes sure you can continue. We tested 22 different ones.
With regular usage a modern smartphone can keep up for about a day, but when you are spending a lot of time sending messages, browsing Facebook, surfing the internet or gaming it might just be a problem to make it through the day. Not a disaster if you are at home and have a charger nearby, but if you happen to be commuting or travelling running out of battery is pretty tiresome. A powerbank will then come in handy. Such a mobile battery has one or more USB-connections and usually offers enough capacity to recharge a tablet or smartphone multiple times. The capacity of powerbanks is usually measured in mAh, where the rule of thumb is that more is better. This does not prove true in all situations, because extra capacity means the powerbank is more expensive, bigger and heavier. We tested 22 powerbanks with a minimum capacity of 4000 mAh, and concluded which ones performed the best.
Battery for on the road
Because of the quick development of lithium-ion batteries it is possible to store a lot of power in a relatively small case. Powerbanks are not at all complicated devices. They consist of one or more battery cells, some electronics that manage the (dis)charging and one or more USB ports. Nearly all powerbanks feature a micro-USB port that is used to charge the built-in battery or batteries. An AC adapter never comes with a powerbank and has to be purchased separately. It is also possible to your smartphone or tablet charger. Aside from the micro-USB port almost every powerbank has one or two regular USB-outputs. These are not used to transfer data but instead deliver 5 volts each. Usually when powerbanks have two USB-outputs one of them is limited to 1 ampere, whereas the other one will deliver 2 to 3 ampere. A higher discharge means your smartphone or tablet will be charged faster but has a lower efficiency and – as we discovered during our tests – has a lower output voltage.