Buying a powerbank: everything you need to know

Milliampere-hours and volts: what is important?

The capacity of a powerbank is given in milliampere-hours (mAh) and describes the amount of charge it can store. The actual stored energy can be calculated using the formula Wh=mAh*Voltage in volts/1000. The voltage of the cells of a powerbank is usually 3.7 volts. Smaller powerbanks have around 5,000 mAh, larger ones can hold more than 20,000 mAh. To calculate how many times a powerbank can charge a device, the energy conversion must be taken into account: the powerbank converts the voltage to the charging voltage of the device (for example, about 5 volts for a smartphone). This leads to energy losses of up to 30 percent depending on the quality of the powerbank. To be able to recharge a smartphone with a 3,000 mAh battery twice, a powerbank with a capacity of around 10,000 mAh is recommended.

The power of the powerbank is given in watts (W). The higher this value, the faster it charges other devices. This is provided that the device allows faster charging – usually referred to as ‘Quick Charge’ or ‘Power Delivery’. This fast charging only works with USB-C ports. In summary, depending on how often you want to charge which device, you need a powerbank with a high mAh value and a high W value for faster charging speeds.

Important details: what to look out for

What should a good powerbank have? Here are some important characteristics that you should consider when buying a powerbank:

Maintaining and storing your powerbank correctly

The following tips will help to ensure that the powerbank lasts for as long as possible:

• The battery of the powerbank should not be completely discharged. It is best if the battery level is at least 20%.

• Avoid extreme temperatures. Extreme heat and cold can damage the battery of the powerbank. The cold also discharges your battery faster. That’s another thing to keep in mind during your adventure.

• Use high-quality cables to avoid charging problems.

• When you’re back from your adventure, store the powerbank approximately half charged somewhere dry.

• Clean the powerbank ports occasionally. The best way to do this is with compressed air. Blowing on the ports also helps, but the moisture in your breath can cause dust and lint to stick. It is important not to blow straight into the charging socket, but at a slight angle. Otherwise you’ll just blow the dust in.

Safety instructions during charging and discharging

Use the original charging cable or a high-quality replacement cable. This reduces the risk of overheating or short circuiting the battery. During charging, the powerbank should be placed on a stable, non-flammable surface. Unplug the powerbank from the mains electricity before using it to charge other devices. This prevents the battery from overloading. Powerbanks with a pass-through function are an exception. These models have pass-through technology, meaning they can be charged and discharged at the same time without any problems.

Also make sure that the powerbank is not physically damaged. Do not drop or stow it next to sharp or sharp-edged objects in your backpack. Cracks, dents or scratches in the powerbank can affect its safety.

Don't forget the travel adapters for charging your powerbanks!

Powerbank on a plane

The International Aviation Authority (IATA) allows powerbanks with a capacity of up to 27,000 mAh and a maximum of 100 watt hours in aircraft. No more than two such powerbanks may be taken per person. Most airlines have adopted this rule in this way. Just to be on the safe side, check which rules are currently valid with the airline you are flying with.

For safety reasons, powerbanks may not be carried in checked baggage, so be sure to pack them in your hand luggage. Take them out at the security check and place them in the box separately for inspection next to the other electronic devices.

Most airlines allow you to use the powerbank on the plane. During take-off and landing, you have to take unplug it, but you can plug it back in afterwards.

Solar powerbank

There are powerbanks that are charged via solar energy. They are particularly handy if you’re away from the public power supply for a long time. They are fitted with solar panels that generate electricity from sunlight.

One disadvantage of solar powerbanks is that it takes a relatively long time to charge – the dimmer the sun shines, the longer it takes. When trekking or on a cycling trip, they can also be attached to luggage and charged when on the go. However, because they are not always optimally oriented towards the sun, they do not charge very quickly or even completely.

In addition, solar powerbanks are usually larger than other powerbanks with the same capacity. There are small solar powerbanks, but small panels usually charge even more slowly. The solar cells are also prone to scratches and knocks. However, if they are damaged, the powerbank can usually still be used like a conventional one.

Separate solar cells are a more flexible option. These usually consist of at least two solar panels that can be folded up. You can then either charge your devices directly or charge your powerbank. Solar panels deliver different power levels because the sun’s radiation is not always the same. Powerbanks can handle this better than smartphones, for example. That’s why it’s better to use solar panels to charge your powerbank and your devices.

Answers to frequently asked questions