18650 Battery Chargers

A bay charger takes the cells out of the mod and charges them on their own. It is cooler, it balances each cell separately, and it is the single easiest thing you can do to make 18650s last longer.

How many bays, and how fast. A two-bay charger like the Nitecore Intellicharger i2 or the Golisi O2 covers a dual-battery mod. Four bays, like the Imren Intellicharger X4, means a spare pair is always ready. A single like the Golisi Needle 1 is the travel option.

A screen is worth having. The ones with an LCD show you the voltage of each cell as it fills, which is how you spot a battery that is on its way out before it lets you down.

Charge at the slower rate if the charger offers a choice. 2A fills a cell quickly and warms it doing so; 1A takes longer and is gentler. The cells themselves are on 18650 batteries, and the mods that take them are on box mods and tanks.