Carrying a flashlight or headlamp on a hike seems like a classic no-brainer. Everyone acknowledges lighting around camp is needed after dark. It’s reassuring that a light’s close by when one’s awakened by strange noises, and it’s much safer to walk around the campsite with a light in hand than move in the dark.
Lighting equipment must be carried by every individual. Lighting is absolutely essential in the event of an emergency, and may be needed when rendering first aid, or when signalling for help.
Flashlights and headlamps in the hiker/backpacker class generally are medium-to-small in size, and consequently use AA, AAA, or smaller lithium coin-style batteries. The choice is yours. I prefer using AA batteries.
Why? AA is standard among all my gear items, such as GPS, camera (if taken along), and so forth. They all use the same size batteries as spares. This is a holdover from my SAR days, when everyone in the group carried the same batteries, among other items, for cross-compatibility.
Okay, you’ve been using your light during the hike off and on. Now you have an emergency, and you have no idea how much juice is left with the original batteries.
BUT, you have a spare set of batteries (you do, don’t you?), so you should know how much guaranteed time you have after the fresh reload.
In the comfort of your own home, load your light with fresh batteries, turn it on, and time it until it winks out. The time you get is how long you can use your light after a battery reload. For example, a conventional Mini-Maglite will run for four hours continuously before going dim.
Handy to know when you’re going to use the light for signalling, moving around camp, etc.
Sound cheesy? Think about it. Unless you do this, you’ll never know for sure how much light you can rely on in a true emergency.
Most of us opt to use LED lights for their enhanced durability and long battery life.
LED lights are rated to shine many, many hours longer than conventional-bulb lights, and for this reason may be impractical to test as outlined above. In the case of LED lights, one can rely on manufacturer-estimated hours of battery life.