Coxio is back with a new S3 portable battery that addresses most of the issues I had during my review of the S2, aka the “world’s first” semi-solid state power bank. It also introduces a few new ones, while adding useful features like a kickstand and an integrated USB-C cable.
As a reminder, these are not true “solid state power banks” despite the marketing hype. The 10,000mAh Coxio S3 uses the same solid-liquid mixed electrolyte found in the S2, making it less prone to thermal runaway than all-liquid lithium-ion batteries found in most power banks. Coxio says its unique semi-solid-state chemistry also lasts twice as long, making the battery good for about 1,000 charging cycles before dropping to 80 percent capacity.
The S3 is more expensive to buy than other 10,000 mAh power banks, typically rated at 300-500 cycles. It lists for $149.98 but sells for less than $70 at the time of this writing. At that price, it should be cheap to own over its long life.
While it’s easy to discount the safety claim – don’t. In September, Anker issued a recall of 481,000 power banks due to fire and explosion hazards. And just last week, the INIU recalled 210,000 power banks sold on Amazon that were involved in 11 fires that caused more than $380,000 in property damage. It’s been a busy year for Power Bank Memories.
Safety aside, Coxio has also fitted the S3 with a number of useful upgrades. In addition to double the battery capacity, you get a folding metal kickstand, a digital display, and a separate USB-C cable that tucks into the frame when not in use. You also get a fast 30W charging input and Qi2 output for devices that support the latest wireless charging standard.
On paper, this all sounds great — and it is — but that’s a big battery heavy When used as a Magsafe charger, it is very pocketable. Measuring 106.9 x 71 x 22.15 mm (4.20 × 2.79 × 0.87 inches) and weighing 245.3g (8.65oz), the S3 adds considerable bulk and heft to my 187g/6.6-ounce iPhone 15 Pro. Fortunately, the S3’s strong array of 18 N52 magnets does a good job of keeping everything together and properly attached for charging.
To test the unit’s rated capacity of 10,000 mAh (7.7V, or 38.5WH), I plugged the S3’s integrated USB-C cable into a ChargerLab Power-Z C240 power meter, which then slipped 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 again from 0 to 92 percent before the S3 power bank ran out. I measured 31.12WH of useful output power from the DC/DC circuit for 80.83% efficiency, which is typical.
The flat, integrated USB-C cable that slips into the S3’s enclosure is extremely useful. Power banks are getting all sorts of unnecessary features these days, but the value of always having a cable at the ready shouldn’t be discounted. While the S3 can’t fully charge my MacBook Pro’s large battery, it can provide a few extra hours of runtime. The S3’s maximum charging speed is only 35W, however, which is about the same for this class of batteries.
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Coxio still sells the more portable 5,000mAh 2, which currently. Available for 49.99. Big S3 currently. 68.99 list and offers increased battery capacity, a display that shows percent remaining, more powerful wired and wireless charging, and the convenience of a kickstand and USB-C cable are always available.
Compared to power banks sold by the likes of Anker, EcoFlo, and hundreds of other alphabet soup brands such as UM, UM CoxioS2 and the new S3 semi-solid state chemistry should be safe and cheap on their own, making them pretty hard to beat if you’re currently in the market.
Photography by Thomas Ricker/The Verge
