Cuktech is a brand you won't be familiar with; it started out as a white-label manufacturer and merged with ZMI — a brand in Xiaomi's vast ecosystem — back in 2022. It is now aiming to gain a global presence on the back of interesting launches; the Cuktech 30 is a massive 40,000mAh power bank with a 300W power budget and Qi integration, and the model I'm looking at is the Cuktech 15 Ultra, a 20,000mAh unit with a 165W power budget.
The Cuktech 15 Ultra is available on Amazon for $87 as of writing, and that's on the higher end of the scale, particularly when you consider that UGREEN's Nexode 20,000mAh Power Bank is selling at $59. That said, the build quality of this power bank is among the best of any I used, and it holds up to the Anker Prime 27650mAh Power Bank — no small feat.
Before we get started, a note on the naming; Cuktech says it chose its name because of the Čuk DC-DC converter architecture, named after Slobodan Čuk. With that out of the way, let's talk about the design. Similar to Anker and UGREEN, Cuktech went with a vertical profile for the power bank, and it is absolutely the right move — it makes the 15 Ultra that much more portable.
There are other niceties; the grey color scheme with the black front looks clean, and the back has a textured finish that makes it easy to hold the power bank. I don't have any issues with the design of the 15 Ultra, and Cuktech did a good job in this regard.
There's a button up front that activates the panel, and you get to see battery life, time to charge devices, and real-time charging metrics on the same page. Ideally, Cuktech should have pushed the real-time charging details to a secondary page as it makes the panel look a little cluttered, but that's a minor quibble. You get all the information you need, and that's what ultimately matters.
As it contains a 72Wh battery, there are no issues taking the 15 Ultra onboard a flight. The 20,000mAh size is adequate to charge your phone a few times over, along with a few accessories, and charging efficiency is in line with other brands I tested recently.
Obviously, you can't charge a phone with a 5,000mAh battery four times with the 15 Ultra; the inherent energy loss while using the power bank means it has an efficiency of just under 60%, so you'll reasonably get 12,000mAh of charging potential. This is the case with all power banks, so you're not missing out with the 15 Ultra when it comes to charging your tech.
On that note, the power bank has three ports in total — two USB-C and a USB-A connector. The main USB-C port goes up to 140W over the USB PD 3.1 standard, and the secondary USB-C hits 65W. The USB-A port is limited to 18W, so it can only be used with accessories. With both USB-C ports in use, you get a 165W power budget. I'm sharing a rundown of the power profiles, and how the 15 Ultra handles simultaneous charging:
- USB-C1 in/out (140W max): 5V/3A (15W), 9V/3A (27W), 12V/3A (36W), 15V/3A (45W), 20V/5A (100W), 28V/5A (140W)
- USB-C2 out (65W max): 5V/3A (15W), 9V/3A (27W), 12V/3A (36W), 15V/3A (45W), 20V/3.25A (65W)
- USB-A out (18W max): 5V/3A (15W), 9V/2A (18W)
- USB-C1 + USB-C2 out (165W max): 100W + 65W
- USB-C1 + USB-A (118W max): 100W + 18W
- USB-C2 + USB-A (83W max): 65W + 18W
- USB-C1 + USB-C2 + USB-A (163W max): 100W + 45W + 18W
I used the 15 Ultra with my Vivo X200 Pro, Find X8 Ultra, iPhone 16 Pro Max, and Pixel 9 Pro XL, and it did a reliable job charging these devices. There's no overheating either, and Cuktech did a good job with thermal management in general.
Ultimately, the 15 Ultra stands out because of its polished design and reliable charging potential. Although Cuktech is a recent entrant to global markets, it clearly knows what it's doing in this area.
With a polished design and good charging potential, the 15 Ultra does what you need of a 20,000mAh power bank.
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