Fenix ARB-L16-800UP

Fenix also brings its flashlight-making expertise to the 16340 format, the rechargeable cell that shares its size with the CR123A battery. The ARB-L16-800UP is the newest version in the range, with a USB-C charging port built directly into the cell, a welcome upgrade over the older micro-USB versions in the ARB-L16 lineup.

With an 800mAh capacity at 3.6V, it provides comfortable runtime for compact flashlights, tactical lights, weapon sights and any other EDC (every day carry) gear using the 16340 or RCR123A format. Charging happens directly through a standard USB-C cable, with no separate charger required: around 2 hours takes it from empty to a full charge, at a maximum current of 0.5A. A small built-in LED shifts from red to blue once charging is complete, a simple, reassuring indicator for everyday use. That built-in port also means one less cable to carry, since the same USB-C lead used for a phone or a power bank works just as well here.

Safety isn't an afterthought either: this battery includes protection against overcharging, deep discharge, short circuits and overheating, with several distinct layers of thermal protection (pressure relief valve, microporous insulation, PTC cathode block). Fenix rates it for around 500 charge cycles, retaining about 70% of its capacity at that point, in line with the rest of the brand's protected cells.

Don't confuse this format with the standard disposable CR123A: although the same size, the voltage differs (3.6V for this lithium-ion cell versus 3V for a primary CR123A), which may not suit every device. Check your light's compatibility before switching to rechargeable. For devices that accept it, this is a genuine gain in convenience and running cost over constantly buying disposables, while keeping the compact size the 16340 format is known for, without the environmental cost of constantly discarding single-use cells.