CUKTECH 20 Power Bank Review: 25000mAh and 140W in a Can-Sized Package

Most power banks are boring. You charge them, they charge your phone, and that is about it. The CUKTECH 20 is a bit different. It is a 25,000mAh unit that can push 140W out of a single USB-C port, which is enough to charge a full-size laptop at proper speed, and it recharges itself at up to 100W so you are not waiting all evening for it to fill back up. I have been using one for two weeks, so here is how it has held up.

Disclosure: CUKTECH sent this unit for review. They had no say in what I wrote and did not see the review before it went live.

What is in the box

• CUKTECH 20 power bank
• USB-C to USB-C cable rated for 240W (6A)
• Fabric storage bag
• User manual

The cable is worth a mention because a lot of manufacturers bundle a cheap 60W lead with a high-output bank, which quietly caps what you can get out of it. This one is rated well above what the bank can deliver, so you will get full speed out of the box. The storage bag is basic but it stops the display getting scratched in a rucksack, which is more than most include.

Design and build

The CUKTECH 20 is a tall rectangular block with rounded edges, a bit like an oversized torch. The top and bottom are capped in a gunmetal grey metal and the body is dark plastic with a matte finish. The front has a semi-transparent window running most of its length, so you can see the outline of the cells inside, with a blue light strip down the middle that glows while it is charging or being charged. It is a lot more interesting to look at than the usual black slab, without being tacky about it.

All three ports sit together on the top end, which is the sensible place for them. Cables all head off in the same direction and it stands upright on a desk next to a laptop without taking up much room. The flat sides mean it also stays put when it is lying down.

It weighs 630g, which you will notice in a jacket pocket. That is par for the course for a 90Wh bank with this much output, but it is worth knowing before you buy. It is not a phone-only unit you forget is there.

The display

The colour screen on the front is the best feature of the whole thing. Instead of four blinking dots it shows the battery percentage in large digits, an estimate of the time remaining at the current load, the total wattage going in or out, and then a separate readout for each of the three ports with its own watts, volts and amps. If you have ever wondered whether your laptop is actually pulling fast charge or just trickling along, this answers it without needing a USB power meter.

It is readable in daylight and switches itself off after a short while to save power. A press of the button just below the screen wakes it up. Holding the button switches it into a low-current mode for earphones, smartwatches and anything else that draws so little that a normal power bank shuts itself off. That mode worked fine with my iWatch and Bose headphones.

Ports and output

There are three ports: two USB-C and one USB-A. They are not equal, and CUKTECH label them so you know which is which.

The 140W port is the reason to buy this. It uses the PD 3.1 standard, which is the same thing a 16-inch MacBook Pro charger uses, so a laptop that can take 140W will get all of it. Most Windows laptops top out at 65W or 100W over USB-C and those charge at full speed too. I tested it with my Lenovo IdeaPad and the display showed 65W going out, which is the same as the mains charger manages.

Phones get the standard PD rates. An iPhone will pull about 27W, and Samsung’s 45W Super Fast Charging 2.0 is supported on the S23 and S24 Ultra. If you have a Xiaomi or Poco phone, CUKTECH is the same team that ran ZMI (Xiaomi’s power bank partner) for years, so their proprietary fast charging is supported as well.

CUKTECH publish their own figures for how far a full bank goes and how much charge you get in the first 30 minutes. These are their numbers, not mine, but they line up with what I saw.

Capacity in the real world

The 25,000mAh figure is the raw cell capacity. Once you account for converting 3.6V cells up to 20V for a laptop, and the losses that come with that, the usable figure is lower. CUKTECH quote a rated capacity of 13,500mAh at 5V, which is honest and about what you would expect for a 90Wh bank.

What that means in practice: a MacBook Air will get one full charge and a bit left over. A 16-inch MacBook Pro with its 100Wh battery will get roughly 60 to 70 percent. A modern iPhone will get three to four charges.

At 90Wh it is under the 100Wh airline limit, so it goes in hand luggage without needing to ask anyone. The capacity is printed on the body, which is what airport staff look for. Perfect for long haul flights in particular.

Recharging the bank

This is where the CUKTECH 20 pulls away from cheaper banks. Plug it into a 100W USB-C charger and it takes the full 100W. CUKTECH claim 40 percent in 19 minutes and a full charge in about two hours.

You will need a charger that can actually deliver that. A 20W phone plug will fill it eventually, but you are looking at most of a day. A 65W laptop charger is a sensible minimum. Pass-through charging is supported, so you can top the bank up and run a phone off it at the same time.

Heat and noise

Pushing 140W generates heat and the bank does get warm under sustained laptop charging. It never got uncomfortable to hold and there is no fan, so it is silent. The internals are rated for over 1,000 charge cycles, which is around three times what a typical budget bank claims. I obviously cannot verify that after a few weeks, but it is a reasonable sign of the cell quality.

Specifications

What I liked

• 140W from one port charges a laptop as fast as its own charger
• 100W self-charging, so it is back to full in about two hours
• The display tells you exactly what is happening, no guessing
• Bundled 240W cable rather than a cheap lead that limits the output
• Under 100Wh, so it flies without any fuss
• All three ports on one end, and it stands upright on a desk
• Low-current mode for earbuds and watches

What I did not like

• 630g is heavy for a pocket
• The second USB-C port is capped at 45W for anything that is not a Xiaomi device
• Only one port does 140W, so two laptops at once means one of them charges slowly

Verdict

If you just want to keep a phone alive on a long day, this is overkill and there are lighter, cheaper options. If you carry a laptop and want a bank that will charge it at full speed and then recharge itself before you have finished your coffee, the CUKTECH 20 does exactly that and the display makes it easy to see it happening. The weight is the only real complaint, and that is what it is for this capacity.

At the time of writing it is £79.99 on Amazon UK, which puts it in line with the Anker and UGREEN 140W banks and slightly under most of them once you factor in the included cable.