At a look
Knowledgeable’s Score
Professionals
- Slimmest-ever 10K energy financial institution
- Semi-solid-state know-how
- 25W wi-fi or 30W wired charging
- Kickstand
- Brilliant sensible show
Our Verdict
The Kuxiu S4 is the slimmest 10K magnetic wi-fi energy financial institution we’ve got examined but. If you need thinner, you’ll should sacrifice half the battery capability with a 5K battery pack.
Value When Reviewed
This worth will present the geolocated pricing textual content for product undefined
Greatest Pricing Right this moment
Value When Reviewed
$89.99
Greatest Costs Right this moment: Kuxiu S4 Semi-Strong Secure 25W Wi-fi 10K Energy Financial institution
Once we reviewed the Kuxiu S3 25W 10K Strong-State Energy Financial institution we referred to as it the “quick 25W wi-fi battery pack that has all of it”. We had been impressed by its built-in USB-C cable, built-in kickstand, and super-clear digital battery show.
Now, the identical firm has launched the S4 Energy Financial institution. It’s not the S3 plus some extra. The truth is it’s a bit lower than the S3, however in a single side that’s nice information—as a result of the Kuxiu S4 is the slimmest 10K magnetic wi-fi energy financial institution we’ve ever examined. And it’s fairly particular in different methods, too.

Simon Jary
Energy financial institution specs
- Capability: 38.5Wh (10000mAh)
- Enter charger: USB-C (30W)
- Output charger: Wi-fi (25W) & USB-C (30W)
- On take a look at charged iPhone to: 177%
- Weight: 7.55oz (214g)
- Dimensions: 4.1 x 2.7 x 0.53 inches (104 x 69 x 13.7mm)
- Colours: Cosmic Orange, Black
Battery capability: 10000mAh (10K) is the biggest battery measurement that you would be able to clamp to the again of your MagSafe iPhone with out it being too cumbersome to pocket—and small pockets will higher admire a 5000mAh (5K) energy financial institution. Learn evaluations of all of the greatest magnetic energy banks we’ve got examined, each 5K and 10K.
Not all 10K or 5K energy banks have precisely the identical capability. To get extra exact you should take a look at the capability in watt hours (Wh). The S4’s 38.5Wh is a smidge below the S3’s 39.5Wh. The common 10K battery capability in watt hours is 37.9Wh.
Velocity: For energy output the S4 is rated on the high 25W, utilizing the newest Qi2.2 wi-fi charging know-how. Solely the iPhone 16 sequence and later can take all 25W, with older iPhones pegged again at 15W (nonetheless a lot quicker than still-available 7.5W battery packs). Notice that the 17e can be restricted to 15W, and the iPhone Air to 20W.
The S4’s USB-C port is rated at 30W so will cost your iPhone quicker if you should energy up as rapidly as doable, however you’ll have to deliver a USB-C cable—not like with the S3 that comes with its personal built-in. The very quickest wired iPhone charging we’ve seen from a magnetic energy financial institution is 45W from The Baseus PicoGo AM52, however it’s unlikely the iPhone will settle for far more than 35W anyway.
When recharging the S4 energy financial institution, the ability enter is 30W—on the high finish of magnetic wi-fi energy financial institution vary.

Simon Jary
Just like the S3, the S4 is constructed utilizing semi-solid-state (SSS) battery know-how that’s engineered for superior security, longevity and thermal stability in comparison with customary lithium-ion battery packs. You’ll be able to skip the subsequent bit should you’re not serious about technical particulars…
What are Semi-Strong State batteries?
Semi-Strong is a transition know-how between conventional liquid lithium-ion batteries and all-solid-state batteries (ASSBs). When all solid-state batteries are mainstream, they’ll seemingly substitute semi, however semi is nearly as good as we’ve got at this time. As soon as confirmed in electrical autos, we anticipate to see ASSB energy banks in by 2028.
Why so lengthy? All-solid-state batteries would require new manufacturing amenities, whereas semi-solid-state batteries are suitable with current lithium-ion manufacturing strains, requiring solely minimal (10-20%) new tools. As such, ASSBs might be costly—perhaps 3-4x—than conventional batteries and so are unlikely to be seen in mainstream laptops till manufacturing ramps up and prices go down..
SSS batteries substitute a big portion of flammable liquid electrolyte with a gel or slurry, usually solely 5–10% liquid stays. The discount of flammable liquid considerably lowers the dangers of thermal runaway, leakage, and fireplace. They’re extra immune to excessive warmth and bodily harm. Because of this we anticipate airways to permit solely solid-state batteries on flights sooner or later. This improved thermal stability additionally means the batteries ought to carry out higher in colder temperatures.
Except for better security, solid-state tech permits the battery to have a better vitality density, to allow them to be made smaller. They need to additionally last more with a better variety of doable cost cycles earlier than capability degradation.

Simon Jary
Thinnest design but
Kuxiu calls the aluminum-alloy S4 “the world’s thinnest 10,000mAh semi-solid-state cell”, and it’s not mistaken.
13.7mm is the thinnest 10K energy financial institution we’ve examined. The earlier champ, the Anker MagGo 10K Slim, is a full millimeter thicker and affords solely 15W energy output. The common depth of a 10K energy financial institution is eighteen.2mm.
Another 10K energy banks are 16mm or 17mm deep, however the common is 20-22mm. The S4 is a 3rd thinner than these chunky beasts. Let’s be trustworthy, it’s not a sliver of an influence financial institution—it nonetheless seems to be massive in comparison with the thinnest 5K battery packs—however it’s the slimmest 10K.
Even the 5K energy banks we’ve examined common out at 10.7mm depth, though the slimmest of all (the BMX SolidSafe Air 5K) is a mere 6.8mm deep.
Kuxiu S4 vs Kuxiu S3: slim vs cable
The S4 is noticeably slimmer than the S3 however lacks its lengthy built-in USB-C cable. Which means Kuxiu has been in a position to make the S4 over 35% slimmer—14mm vs 22cm.
Whereas we love a built-in cable on a magnetic energy financial institution (wired charging is all the time quicker and a cable makes recharging the ability financial institution itself much less problem), we additionally want them to be as slim as may be.
That’s the foremost compromise between selecting between the S3 and S4, however there are extra variations. Learn our Kuxiu S3 assessment for extra particulars.
Each energy banks characteristic a stand, and the S3’s stand is bigger and extra strong than the S4’s bottom-mounted pull-out however the S4’s performs effectively sufficient.

Simon Jary
Each have a digital show so you’ll be able to see exactly how a lot energy stays within the energy financial institution—most make do with 4 tiny LEDs, every of which represents 25% battery cost, in comparison with the precise quantity a digital show readout offers you.
The S3’s is evident to learn however reveals simply the remaining battery cost. The TFT show on the S4—tucked behind the stand—is smarter and extra colourful, exhibiting battery well being, working temperature, battery stage (remaining cost), wi-fi charging energy and USB-C enter/output energy plus battery security alerts the place acceptable.
You may not have to know all that information however it’s there, introduced on three digital circles.
Lastly, the Kuxiu S4 is obtainable in a shocking Cosmic Orange to match the iPhone 17 Professional and Professional Max in addition to the identical Black because the S3.
Recharging efficiency
At Macworld we produce a battery efficiency report for all the ability banks that go by way of our labs.
There’s nothing fancy involving microscopes and spectrometers. We merely drain an iPhone’s battery to 0%, join the ability financial institution and see what number of occasions it could recharge the telephone. If it fills the telephone up with juice to spare, we wait until the telephone has run out once more and repeat till the ability financial institution is empty.
One of the best rating we’ve got acquired from a 10000mAh (10K) energy financial institution is 190% (the 15W EcoFlow RAPID 10K), with a mean rating of 166%. The Kuxiu S4 scored an above-average 172%—across the similar ballpark because the S3.

Kuxiu
Value
The Kuxiu S4 10K Magnetic Energy Financial institution is priced at $84.99 or £64. The S3 is cheaper at $68.99/£54, even with its built-in cable.
If you need the thinnest 10K magnetic energy financial institution, you’ll have to dig a bit deeper, however your trouser-pocket lining could thanks for it over the long run.
For extra choices we’ve got examined and reviewed the greatest magnetic wi-fi energy banks.
Must you purchase the Kuxiu S4 25W Wi-fi 10K Energy Financial institution?
First issues first: the Kuxiu S4 is the slimmest 10K magnetic wi-fi energy financial institution we’ve got examined but. If you need thinner, you’ll should sacrifice half the battery capability with a 5K battery pack. The S4 carried out above common in our recharging exams. In the event you can sacrifice the slimness, think about its S3 sibling that boasts an built-in USB-C cable, however we salute the S4 for being the slim semi-solid-state champion… and we love the Cosmic Orange possibility.
