If you’ve bought a powerful LED flashlight, a rechargeable battery pack ... (18 mm in diameter and 65 mm long). The batteries usually use lithium-ion technology. However, lithium isn’t ...

to be the king of flashlights ... pesky D-cell batteries is kind of ridiculous in this day and age. So [Travis] decided to upgrade it to make use of the ever-so-common, 18650 lithium-ion battery.

Acebeam also claims that the X75 is the "brightest powerank flashlight." With a built-in 14.4V, 4,250mAh rechargeable Li-ion battery, I have no doubt that's true. But in all reality, a flashlight ...