Living in Ukraine in 2024 involves many extra chores, one of which is always making sure you have enough power banks and charging stations to keep your internet, fridge, lights, and devices charged during frequent blackouts and non-stop rounds of "liberation." Therefore, when Cuktech asked me if I was interested in trying their recently announced S15 power bank, I gladly agreed. It is a 73Wh compact power bank with a lot of power inside for just $49.99.
Note: Cuktech provided the review unit without any editorial input or review pre-approval.
What is in the box:
- The Cuktech S15 power bank
- A 6A USB-C to USB-C cable
- User manual
As you can see, the box is pretty spartan in terms of bundled accessories, but I did not expect to see anything beyond that. I am just glad that the bundled cable supports Fast Charging, and it is not a crappy one. Also, colored connectors are a neat touch—good attention to detail.
First touches
The Cuktech S15 is made of gray plastic with one black textured side. It has a small inscription that states the battery capacity, which is 73.44Wh rated and 72Wh typical, and that the power bank is "AirLine Safe." This refers to the 99Wh limit on batteries you can take on a plane.
Ports are located on the left side, and they include two USB-C and one USB-A. The input port also has a color-accented connector, making it easier to know where to connect the power bank to charge. Also, the entire port side of the S15 has a light-blue contour, which, at first glance, seems like an LED. Sadly, it is not.
The S15 SE has one power button and an LED display to display the current charge level. The power button boasts 85W max power out (all ports combined, but we will get to that later), and you can press and hold it to enter low-voltage mode.
Overall, the power bank is impressively compact for its capacity and power output. I like its unconventional squarish design, but I also think some will find it a bit odd to carry in a laptop bag. In this regard, a more squished design is better for portability.
As for dimensions and weight, the S15 SE is 5.98 x 2.05 x 1.73 inches or 152 x 52 x 44 mm and weighs roughly 1.1 lbs or 500 g. In the image below, you can see how the S15 SE compares to a 60,000 mAh (220Wh, 20W max) power bank and another one 20,000mAh (74Wh, 50W max).
And another comparison:
Charging the S15 SE
The Cuktech S15 SE can charge up to 65W (20V 3.2A), assuming you have a brick that can deliver such power. I charged it with a 100W adapter, resulting in 0-100% time of just 90 minutes. The ability to charge the S15 SE in such a short time is one of my favorite things about this power bank since my monster of a power bank with 220Wh capacity takes 10 hours to top up at just 20W max.
What also impressed me was that despite the compact footprint and quite fast charging, the S15 SE was barely warm to the touch, with the hottest spot staying just shy above 93F (34C).
As for chemistry, the Cuktech S15 uses Li-ion batteries, which means their lifespan is about 300 cycles before any noticeable battery degradation. Considering that and fast charge support, I would recommend not draining the power bank below 10-15% nor charging it higher than 90% for longevity"s sake.
Charging with the S15 SE
Now, let"s charge a bunch of devices. Right off the bat, do not look at the mAh value. It depends on voltage and amps, which means 20,000 mAh are often not the same in two different power banks. What you need to measure the battery capacity is Wh, which is voltage times amps. Cuktech makes it clear that the S15 SE has a rated capacity of 73.4 Wh. Here is what that gives you.
I charged my iPhone 15 Pro from 15% to 90% (again, to preserve the battery):
| iPhone 15 Pro - 10% to 90% | |
|---|---|
| Charge cycle 1 | 100% to 84% (16% consumed) |
| Charge cycle 2 | 84% to 68% (16% consumed) |
| Charge cycle 3 | 68% to 46% (22% consumed) |
| Charge cycle 4 | 46% to 31% (15% consumed) |
| Charge cycle 5 | 31% to 10% (21% consumed) |
Quick math time: the iPhone 15 Pro has a 12.7 Wh battery. 12.7 x 5 = 63.5 Wh. With 10% left in the power bank, I could probably squeeze over half the extra charge.
The S15 SE charged my M1 13-inch iPad Pro from 1% to 100% and retained 34% of its charge. The iPad has a 40.8 Wh battery, so the capacity checks out to over 60 Wh of usable charge. Remember that no charger or power bank has 100% efficiency, and there is always some power loss due to heat and other factors. Also, the power bank drains faster as you get closer to zero, but voltage and amps remain on point from dead to 100%, which is important for battery health.
Cucktech says the conversion efficiency is at 75%.
As for heat, the S15 SE stays cool to the touch even when fast charging. However, things get a bit hotter when using all three ports at once. Not to the point of getting a first-degree burn or having safety concerns, but still significantly warm, with the hottest spot in the display area being 125F or 52C.
Also, the USB-A port has one odd quirk: plugging a Type-A cable while charging another device with a Type-C cable results in the latter dropping a charge for a second. It is like the power bank"s brain resets for a brief moment as you try to use the old-school USB interface. It is by no means a deal breaker but a quirk nonetheless.
85W Max
Now to the "85W Max" statement. Sadly, it is the maximum combined power. You cannot have 85W on a single port. The first USB-C (the one with the colored connector) peaks at 20V 3.25A (67W). Therefore, you can have one USB-C saturated to the max and another one charging at 20W. My testing confirmed the spec, with my laptop taking 60W from the first port and my iPhone sipping 20W from the second port.
While I wish the power bank could give me a full 85W on a single port, it is still nice to see it being capable of charging a laptop (with a CPU stress test, mind you) and my iPhone simultaneously. Of course, it drains fast in such a scenario, but the point is that you can have both of your devices charging without major compromises. Thumbs up for that from me.
For reference, here is the list of all modes the Cuktech S15 can operate at:
| All ports | 5V 3A (5V 1A on each port) |
|---|---|
| USB-C 1 | 5V 3A, 9V 3A, 12V 3A, 15V 3A, 20V 3.25A 67W Max |
| USB-C 2 | 5V 3A, 9V 3A, 5-11V 3A 33W Max |
| USB-A | 5V 3A, 9V 3A, 5-11V 3A 33W Max |
Conclusion
The Cuktech S15 SE is a great power bank. Compact, powerful, and cool under load, it ensures that even powerful gadgets have enough extra power when needed. And with a proper USB-C cable in the box, there is no need to worry whether your existing cables can deliver the maximum charge rate. Finally, thanks to 65W charging support, it will get back to 100% in the same time the modern iPhone takes to charge fully.
For $49.99 on Amazon, it is very easy to recommend.
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