13,800-mAh AAA rechargeable battery costing $1.15 gets tested

An exciting product has been taken for a spin by a mysku.club forum member named INN36. A set of 2 AAA batteries rechargeable through USB-C for an equivalent of $1.15 each (₽182 per pair) seems like a good deal. It instantly becomes an unbelievable deal after a single look at the claimed capacity: 13,800 mAh per battery. Presumably, this is for its output voltage, which is ~1.5 volts; accounting for voltage reduction losses of around 10 percent, this should mean there is a 3.8-volt, 5.99-amper-hour lithium-based battery hidden inside that tiny casing.

After receiving the box, INN36 started by weighing the batteries. At around 0.26 oz per item, both proved to be suspiciously light considering the crazy specs listed by the seller.

A free dual USB-C cable came bundled with the batteries, as promised in the listing. An attempt to charge one of the batteries showed it was accepting around 0.19 A at 5.2 V, which sounds normal for a lower-capacity lithium-based battery. The charging process was completed after as little as 1.5 hours, putting a big heavy damper on any remaining hopes that the product's capacity could be reasonably close to what was stated in the listing.

A 100-mA controlled discharge test revealed that the battery's actual capacity at a voltage of 1.5 volts was laughable at around 380 mAh. Then, the forum member proceeded with their experiments by taking the product apart. Under the plastic wrap, they found a minuscule cell rated for 180 mAh and 3.7 V, alongside a small PCB. At this point, we should note that decent non-rechargeable 1.5-V batteries deliver over 1,000 mAh at 1.5 volts.

The takeaway is largely predictable. When a product seems too good to be true, it most likely is. There are rechargeable batteries that claim to deliver similarly unrealistic capacities on other platforms, like Aliexpress: 5,500 mAh AAA, and it is easy to find "increased capacity" battery listings for older iPhones as well as certain Android phones, too. It is anyone's guess what capacity these batteries actually have, and if they even are safe to use; user reviews for listings like this tend to be unhelpful to outright misleading. That said, with phones older than three or four years, there is often no option but to turn to Chinese sellers and makers as 1st-party components become unavailable.