Emergency power on the go: Which compact power bank is the best?
24/7/2026
Translation: machine translated
Pictures: Lorenz Keller
If you want to charge your phone on the go, you need a small and light power bank. I tested five popular models. Which one is convincing in everyday life?
With over 3000 power banks in the range, choosing the right one is difficult. I have selected the smallest and lightest power banks that can charge many smartphone models once with their 5000 mAh capacity. Many people carry such batteries around for emergencies. The big comparison shows which of the five models is convincing in various categories, with a maximum of five points to be scored in each.
Size and weight: 100 grams and less
Probably the most important category: These power banks are designed for use on the go – they go into a bag or backpack, in case the phone's battery indicator goes to zero. Every gram and every centimeter counts here.
To be able to compare the differently shaped power banks, I not only determined the weight but also calculated the volume to estimate how much space they take up in a bag. In addition, I consider protruding cables and other extras that could interfere with transport.
Anker Nano: The 101 grams of weight are close to the average of the other models. The volume of 63 cubic centimeters is slightly above average. The shape of a thick lighter is easy to store, and the retractable USB-C plug does not interfere. All in all, average, hence the three stars.
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Nitecore NB Air: At 88 grams, this model is the lightest in the test. The volume of 47.4 cubic centimeters is also smaller than many competitors. The thin, elongated shape can be easily stored in a trouser pocket. However: I need an additional USB-C cable to use it
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Sharge Flow Mini: In contrast to the competition, this battery is bulkier. A kind of round, elongated battery with an attachment. The big disadvantage: The integrated cable can serve as a carrying strap, but it protrudes from the surface, just like the plug adapter. The risk of it getting caught is high. At 104 grams, the Sharge Flow Mini is also the heaviest power bank in the test – albeit only by a few grams. The volume is also large at 63.3 cubic centimeters.
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Xiaomi UltraThin Magnetic: This battery looks like a 6 millimeter thin metal plate – no other model is so slim. The volume is also smaller than all others at 41.7 cubic centimeters. The 99 grams of weight are average. If the phone supports Magsafe or the Qi standard for wireless charging, I don't need an additional cable.
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Xtorm 20 Watt: At 67.4 cubic centimeters, I measure the highest volume for this battery. In terms of weight, the model is average at 100 grams. The shape resembles a thick lighter – the design and plug are very similar to the Anker Nano.
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Charging: Not all achieve the same
On paper, there are no major differences. All five test candidates charge devices with 18 to 22.5 watts. The top values can be confirmed with a multimeter, but in everyday life, I still notice differences. This is because smartphones are not supplied with power uniformly; an interaction between the power bank and the device regulates the charging process. I tried this with an iPhone 15 Pro – and made control measurements with an Android device to detect any deviations.
In terms of capacity, all models look the same at first glance: manufacturers state 5000 mAh. But this advertising figure is deceptive, as the watt-hour specification shows. There, the values vary from 18 to 19.4 Wh depending on the model. I also measured how much capacity the batteries actually deliver in everyday life.
Anker Nano: It takes a full two hours for the iPhone to charge from 2 to 100 percent using the integrated folding plug. The capacity is almost exhausted afterwards. In the second attempt, I charge the smartphone to five percent, then the power bank is empty. Both are not good values. The external battery only gets slightly warm at 35 to 38 degrees.
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Nitecore NB Air: After about 90 minutes, the phone connected by cable is charged – a good value. The remaining capacity is then still sufficient to charge the iPhone to 41 percent. No other test candidate achieves this much. The only noticeable thing: The Nitecore power bank gets significantly warmer than all other models at 40 to 45 degrees.
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Sharge Flow Mini: After only 80 minutes, the iPhone is fully charged. This is a record in this test. The remaining capacity is sufficient to charge the device to 19 percent again – the second best result in the test. The temperature development remains moderate at 35 degrees.
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Xiaomi UltraThin Magnetic: The Xiaomi model also charges quickly: In 90 minutes, the iPhone connected by cable is fully ready for use again. However, the power bank is almost completely discharged. Only four percent remain – the worst result in the test. The battery remains rather cool at 30 to 35 degrees.
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Xtorm 20 Watt: With two hours and ten minutes, the Xtorm takes the longest. However, 17 percent remain afterwards, with which I charge the device in the second round. The temperature of 35 to 40 degrees is average.
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It also becomes clear in this test: A power bank with 5000 mAh cannot automatically fill a smartphone with 5000 mAh, because a lot of capacity is lost during the charging process. The iPhone in my comparison has a capacity of 3300 mAh. As a guideline, many tested batteries manage to charge around 3500 mAh in a smartphone. The top model achieves the equivalent of around 4600 mAh.
Workmanship and accessories: Some have two connections
Anker Nano: Dark color, mediocre plastic – the Anker power bank looks quite boring. Two USB-C ports are available: One of them is a foldable plug with which you connect the power bank directly to the smartphone. The plug seems quite stable. The manufacturer also includes a USB-C cable for the second port. If you use both plugs simultaneously, the power per port is significantly reduced.
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Nitecore NB Air: The carbon surface feels really high quality. Too bad: The manufacturer does not include a USB-C cable – but you need one to charge at the only port. The Nitecore is waterproof, unlike all other candidates. According to the IPX7 standard, it can withstand up to 30 minutes and one meter underwater.
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Sharge Flow Mini: The design is unusual and a bit wild. Unfortunately, the manufacturer refrains from transparent insights into the technology, as he offers with other devices. The materials are nevertheless high quality. As the only manufacturer, he installs a fixed USB-C cable – plus a removable USB plug with a protective cap. I can replace this with the enclosed Lightning adapter or use my own cable of any length. However, the connection is recessed, cables with thick plugs do not fit.
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Xiaomi UltraThin Magnetic: With its silver metal back, it looks elegant – and is also available in other colors. In addition, it can be magnetically attached to MagSafe magnets and charges smartphones wirelessly via Qi. A USB-C port serves as an alternative.
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Xtorm 20 Watt: The black plastic is reminiscent of Anker's material. Thanks to the ribbed surface and the yellow button, the design looks more exciting. The USB-C plug folds out; I use the second USB port with the included cable.
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Price: 100 percent price differences
Anker Nano: At the time of testing, the Anker model costs 24.70 Swiss francs – the cheapest offer in the test. In the last three months, the power bank has repeatedly been available in the shop for less than 20 Swiss francs. However, there are already power banks with the same capacity in the shop for half the price – therefore only four out of five points.
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Nitecore NB Air: At 39.90 Swiss francs, the Nitecore costs almost twice as much as the cheap models in the test. In recent months, the price has hardly ever been lower.
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Sharge Flow Mini: At 27 Swiss francs, this model ranks 3rd. The Sharge is currently not available cheaper.
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Xiaomi UltraThin Magnetic: No model in the test is more expensive than the Xiaomi power bank at the time of testing: 57 Swiss francs – significantly more than all other candidates. If you strike at the right time, you save a few francs.
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Xtorm 20 Watt: At 25.70 Swiss francs, the Xtorm battery ranks 2nd – close to the Anker and Sharge models. In the last three months, the power bank was usually a few francs more expensive; but if you're lucky, you can also get it for under 20 Swiss francs.
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Conclusion: Two winners
If I add up all the points, two models are at the top with 14 points each: Nitecore NB Air and Xiaomi UltraThin Magnetic. Although neither can be plugged directly into the smartphone, they impress with their thin and light design – and appear to be of higher quality than the competition.
If you want a wireless model, the Sharge Flow Mini is the best choice. Thanks to its plug and permanently installed cable, it offers two charging options. However, I am bothered by the fact that both protrude and can get caught in a bag or backpack. Xtorm 20 Watt and Anker Nano offer foldable plugs – both are solid overall, but nothing more.
I have weighted the result. The topic of "charging" is most important to me, followed by size and weight, and then workmanship. I weigh the price the least – all five candidates are affordable in absolute terms.
However, the ranking does not change much: Nitecore and Xiaomi are tied at the top, followed by Sharge. Only Xtorm stands out a bit from Anker – but in everyday life, the differences are small.
I personally recommend the Xiaomi model. The magnetic charging function convinces me the most. In an emergency, I attach it directly and magnetically to my Google Pixel 10 Pro.
Lorenz Keller
Senior Editor
Lorenz.Keller@digitecgalaxus.chGadgets are my passion - whether you need them for the home office, for the household, for sport and pleasure or for the smart home. Or, of course, for the big hobby next to the family, namely fishing.
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