"LED" stands for "light-emitting diode". LED technology is now available in flashlights. Popular brands include Maglite, Streamlight, Surefire, Inova, Coast, Pelican, Dorcy, Energizer and Garrity.
The LED Advantage
Red LEDs have been available for decades. Cheap and powerful white LEDs now make LED flashlights clearly superior to traditional incandescent flashlights.
LED bulbs hardly ever need to be replaced. LED design and integration company LEDdynamics says that LEDs can sustain up to 100,000 hours (eleven years) of use.
LED flashlights (known as torches in some countries) last longer between battery changes. SureFire offers their 6P flashlight in both LED and incandescent versions. The LED version is over twenty percent brighter, yet lasts eleven hours on a pair of 123A lithium batteries versus one hour for the incandescent.
LED Brightness: Lumens versus Watts
More LEDs doesn't mean brighter. A one-LED flashlight can be brighter than a flashlight with 3, 4 or even 9 LEDs.
Total brightness is measured in lumens. 10 to a 100 lumens is common.
•10 lumens is about the minimum practical brightness.
•30 lumens will be bright enough for most purposes: lighting up trails when walking, fixing car engines, searching for lost items under the sofa.
•"Tactical" super bright police/military flashlights start at 90 lumens and can reach a few hundred lumens. They are good for lighting up more distant objects.
LEDs are also measured in watts. This is the power input, not the brightness output. Most general-use flashlights top out at 1 watt. 90 lumen police flashlights are typically 3 watts.
It is difficult to compare lumens with watts. Manufacturers claim anything from 10 to 80 lumens per watt (manufacturers probably report the rated wattage of the LEDs, not the actual wattage driven by the electronics). Average claim is about 30 lumens per watt.
So, brightness is best compared using lumens, not watts. However 30 lumens per watt can be assumed if lumens are not stated.
Dimmer can be Better
The lowest brightness of a flashlight is important. Dim light is
•Good for conserving battery life (super bright also means super battery-eater), especially useful in emergencies.
•More comfortable for reading at night.
•Less likely to wake up companions when rummaging around in a tent.
Premium flashlights have a low and high power setting. Some have more than two levels of brightness. Others have a separate red LED that not only conserves the battery but also protects night vision.
An alternative is to carry two flashlights, one dim and another bright (much like carrying a pocket knife and a machete). This is practical with today's lightweight flashlights. A backup flashlight can be a lifesaver.
LED Flashlight Batteries
AA batteries are best.
Small, bright LED flashlights can be powered by one or two AA batteries. These are the best all round performers (cost, capacity, availability) for general portable use. A single AA alkaline can power a flashlight for hours.
AA batteries have wide market support. There are
•lithiums (lightweight, last longer than alkalines, work well in the cold, expensive)
AAA batteries are the next best. Flashlights with three AAAs are a popular configuration.
Specialized batteries such as button cells or CR123A lithiums should be avoided. CR123A batteries may give good performance, but replacements can be difficult to obtain in remote areas.
Batteries are part of an overall portable or emergency power supply plan. Equipment that use the same battery type (GPS, camera, flashlight, MP3 player, radio, walkie-talkie) can share batteries in a pinch. Solar chargers for AA and AAA batteries are available, making these batteries even more attractive.
LED Flashlight Features
Brightness and batteries are the most important issues when choosing a flashlight. Additional features include
•Regulated power or voltage, to maximize and even-out battery power. Instead of being too bright when the battery is new and too dim later, a more constant level of brightness is maintained.
•Flashing feature, to attract attention in an emergency.
•Focusing head to adjust the width of the beam. These are normally available only on single-LED flashlights.
•Safety switch to prevent accidental switching-on of the flashlight, draining the battery. End-twist switches and recessed push-button switches are also good.
•Momentary-on switch, for signaling in Morse code.
•Additional red LED for protecting night sight.
•Floating (buoyant) body. This prevents the flashlight from getting lost if dropped into water, but increases the size of the flashlight.
•Hole to attach a lanyard.
•Flat sides to stop the flashlight from rolling when placed on an even surface.
Upgrading to LED Flashlights
LED flashlights are overwhelmingly superior to traditional incandescents. With LEDs, a backpacker or homeowner setting up an emergency preparedness bag
•Need not worry about bulbs burning out.
•Can carry up to ten times fewer batteries.
This translates into better safety and a lighter backpack. Aside from the higher initial cost, there is no downside.
Read more at Suite101: White LED Flashlight Brightness, Lumens, Watts: Super Bright LED Torches for Hiking, Tactical and Emergency Use http://backpacking-gear.suite101.com/article.cfm/led_flashlight_basics#i...