Heraclitus, a Greek philosopher (about 500 BC), wrote "Nothing endures but change."
A new class of lower cost technical dive light has supplanted the corded light head and battery canister form factor of the past. LED technology has advanced to the point where inexpensive backup lights are as bright or brighter than previous generation primary lights. With reliability and energy capacity advancements in rechargeable battery technology even the form factor of the large canister is being questioned.
Today this means the main operational difference between a backup and primary light is the burn time, with many divers including penetration divers forgoing the traditional canister primary and two handheld backups in favor of three modern handhelds that can each serve as primary. The multiple handheld primary approach is much lower cost with better reliability and redundancy. However, for extreme environments that demand the maximum burn time with maximum lumen output the newest generation canister lights seem to still be the preferred choice of exploration divers.
Previous generation halogen and HID bulb primary lights were powered by unreliable NiCad, NiMH or lithium chemistry rechargeable batteries and best practice was to dive carrying two backup lights, both powered with non-rechargeable alkaline chemistry batteries. Today, both high-power LED and next generation lithium-ion rechargeable battery technologies are now well established for mission critical applications. Thus, NSS Cave Diving Section standards were updated in 2020 and no longer require alkaline batteries for backup lights in their training program equipment requirements. TDI and IANTD training standards have been similarly updated to delete reference to battery requirements. Only GUE still says backup lights should be powered by alkaline batteries. Dive Gear Express continues to offer an alkaline disposable battery powered backup light, although all our other backup lights are now powered with lithium-ion rechargeable batteries.
