Kuxiu is back with a new S3 portable battery that solves most of the problems I encountered while reviewing the S2, aka the “world’s first” semi-solid state power bank. It also introduces some new ones, adding useful features like a kickstand and integrated USB-C cable.
As a reminder, these are not true “solid state power banks” despite the marketing hype. The 10,000mAh Kuxiu S3 uses the same solid-liquid mixed electrolyte found in the S2, making it less prone to thermal runaway compared to the all-liquid lithium-ion batteries found in most power banks. Kuxiu says its unique semi-solid state chemistry also lasts twice as long, making it good for about 1,000 charging cycles before the battery capacity drops to 80 percent.
The S3 is more expensive to buy than other 10,000mAh power banks, typically rated for 300-500 cycles. It lists for $149.98 but is often discounted, selling for less than $70 at the time of this writing. At that price, it should be cheap to adopt over a long lifetime.
While it’s easy to discount a security claim – don’t do it. In September, Anker recalled 481,000 power banks due to the risk of fire and explosion. And just last week, INIU recalled 210,000 power banks sold on Amazon that were caught in 11 fires that caused more than $380,000 in property damage. It’s been a busy year for power bank recalls.
In addition to security, Kuxiu has also made several useful upgrades to the S3. In addition to double the battery capacity, you get a folding metal kickstand, digital display, and detachable USB-C cable that tucks away into the perimeter when not in use. You also get a fast 30W charging input and up to 25W Qi2 output for devices that support the latest wireless charging standard.
On paper, this all sounds great – and it is – but that’s the big battery. Heavy When it’s used as a MagSafe charger, and it’s much less pocketable. At 106.9 x 71 x 22.15 mm (4.20 × 2.79 × 0.87 in) and weighing 245.3 grams (8.65 ounces), the S3 adds considerable bulk and weight to my 187-gram/6.6-ounce iPhone 15 Pro. Luckily, the S3’s strong array of 18 N52 magnets does a good job of keeping everything together and properly aligned for charging.
To test the unit’s 10,000mAh (5,000mAh at 7.7V, or 38.5Wh) rated capacity, I plugged the S3’s integrated USB-C cable into a ChargerLab Power-Z C240 power meter, which then fit into the USB-C jack on my iPhone 15 Pro. I was able to charge the iPhone from 0 to 100 percent once, and then from 0 to 92 percent before the S3 power bank emptied. I measured 31.12Wh of useful output capacity from the DC/DC circuit, for 80.83 percent efficiency, which is typical.
The flat, integrated USB-C cable that tucks into the perimeter of the S3 is extremely useful. Power banks these days come with all kinds of unnecessary features, but the value of always having a cable at the ready should not be underestimated. While the S3 can’t fully charge my MacBook Pro’s larger battery, it can provide a few extra hours of runtime. However, the maximum charging speed of the S3 is only 35W, which is on par with batteries in this category.
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Kuxiu sells the still more portable 5,000mAh S2, which is currently available for $49.99. The larger S3 currently lists for $68.99 and features twice the battery capacity, a display that shows remaining percentage, more powerful wired and wireless charging, and an always-available kickstand and USB-C cable.
Compared to, um, power banks sold by Anker, EcoFlow and hundreds of alphabet-soup brands. kuxiuThe S2 and new S3 semi-solid-state chemistries should be safe and affordable, making them very hard to beat if you’re currently in the market.
Photography by Thomas Ricker/The Verge
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