Editing Tactical light (section)

===Battery===
Primary [[Lithium battery|lithium batteries]] are commonly used with tactical lights, due to the long shelf life, high [[specific energy]], and gradual voltage decay over the battery's lifetime. [[Alkaline batteries]] also provide moderately long [[shelf life]] and low initial cost. In powerful lights with high current draw, the high [[internal resistance]] of alkaline cells results in decreased effective capacity. As the rate of discharge increases, a greater proportion of the cells' power is wasted in its internal resistance. Because of their low internal resistance, lithium batteries are often the primary cell of choice when a high rate of discharge relative to [[nominal capacity]] is required. Lithium cells will also provide better performance in cold weather than alkaline cells. High-quality lithium cells are less prone to leakage of electrolyte than alkalines.

Rechargeable batteries, such as [[NiMH]] and [[Nicad]], are economical options for lights with heavy usage. Rapid capacity loss in comparison to alkaline and lithium batteries limits the use of rechargeable cells to lights in frequent use. With a [[lithium-ion battery]] or a [[low self-discharge NiMH battery]], rechargeable battery shelf life is extended. Several new models of tactical flashlights incorporate the ability to be recharged from a USB cable.