Nitecore NL1840 – Rechargeable 18650 Li-ion Battery (4000mAh, 3.6V)

No, this cell has no built-in USB port. It charges inside a light that supports it, such as the HC60 UHE, or in a Nitecore charger such as the UM2.

It ships with the HC60 UHE headlamp and fits lights that take a protected 18650. Check it seats properly before relying on it.

Because a flashlight this bright draws serious current, and an unbranded or unprotected cell under that load is how people end up with a hot pocket. Nitecore cells carry protection circuitry and are matched to their lights.

Several hundred full charge cycles with normal use. What shortens a lithium cell's life here is heat: a torch left in a parked car in Dar ages faster than one used every night.

Around half charged, in a cool place, terminals covered. Never store one flat, and never loose in a pocket or a drawer with keys and coins.

Spare lithium cells travel in cabin baggage only, never in checked luggage, with the terminals taped or in a case. Check the count your airline allows before you travel.

Stop using it. A swollen or dented lithium cell should be taken out of service. Do not charge it, do not puncture it, and dispose of it through a proper recycling point rather than in household waste.

When runtime has dropped noticeably against when it was new, or when it will not hold a charge for a week unused. A light that used to last a night and now lasts an hour is telling you the cell is done.