Anker Nano Power Bank 22.5W Review

Design

• 77 x 36.8 x 25 mm
• 100g
• Sturdy flip-out USB-C

Anker knows how to put a neat spin on a generic battery bank design. The Anker Nano Power Bank is a palm-size battery you could fit comfortably into a jacket pocket. But it also has a flip-out USB-C connector. 

The idea is you can stick it to the bottom of your phone and leave it hanging there, charging your phone as you use it. 

While the concept makes me a little nervous, Anker appears to have executed it well. There’s zero lateral wobble to the USB-C connector, and basically no kind of normal phone motion will make it begin to flip back into the body while you handle your mobile. It feels secure enough. 

I’m not sure I prefer the feel of an extra 100g hanging onto my phone versus a cable sticking out of it. But it’s much less likely to cause issues if, say, you’re on a train with luggage and then suddenly have to deal with unplugging and stowing away that cable when your stop arrives. 

The Anker Nano 22.5W can also be used as a more conventional mini battery pack, using the USB-C on its side. Either one can supply the same amount of power, using the USB-C on its side.

There is also a little button. This lights-up the 4-LED battery level on the front. While these have a certain elegance, the Ugreen alternative has a full numerical display for a more fine-grain charge level indicator.

Unsurprisingly, the Anker Nano doesn’t have any of the company’s flashier extras like app support. It would be overkill, a waste of production budget, to fit such stuff in. You can get it in blue, green, pink and white colours, though, and Anker makes an Apple-friendly Lightning version too.

Performance

• Charges a 5000mAh phone to around 66%
• Fair power efficiency
• Outputs 3678mAh

One eye-catching element of the Anker Nano is that it has exactly the same capacity as an awful lot of the best Android phones, 5000mAh. And on the pace side, the 22.5W claimed output is not far off the maximum charge speed of an iPhone 16. 

Testing these external batteries teaches you pretty fast that battery power is lost at every part of the chain, though, so I tested a couple of 5000mAh phones to see how far the Anker would get. It only took the Xiaomi 14T from flat to 58%, and the Sony Xperia 1 VI from flat to a much more reassuring 66%.

Disappointed? It’s the reality of all of these power banks, particularly the lower-end ones, in my experience. And don’t forget phones’ reporting of battery level isn’t entirely linear either. 

Taking a tester tool to the job to get a better idea of what we’re getting here, it took 18.48Wh to charge the Anker Nano. That’s equivalent to 4994mAh, which is strangely low for a 5000mAh battery (power used is usually higher than the claimed capacity). Charging took 1 hour 48 minutes, which suggests the average charge power across that time was 10W. It spends a good chunk of that time at 14W, but slows down towards the end. 

I put it through a second round of testing. That time it took 18.43Wh — almost identical to the first run. This suggests either that my sample actually has capacity of less than 5000mAh or that it holds onto a chunk before refusing to charge. They have the same effect on the end user: lower useful capacity. 

When charging a device, it put out 13.61Wh (3678mAh). That means we got out 73% of what we put in. And then we’re getting closer to the kind of charge level we saw in the Sony Xperia 1 VI test. 

73% efficiency is not ideal. It’s one of the lower scores I’ve seen from an Anker battery, which can tip over 80%. But then I’ve mostly benchmarked far higher-end power banks than this one, like Anker’s popular Prime 20,000mah. It’s an acceptable performance level for a budget power bank, but a sign you had better like the flip-out USB-C design before buying. 

Should you buy it?