2. Required brightness. EDC flashlight need to be quite bright, but since it need to be portable, the body should be small enough. What I mean is that, the EDC flashlight need to be bright than that used for walking, and other purposes. So, the LED’s power need to be large. If it uses li-ion battery, the power should be 3W; if uses dry battery, the power is about 2W.

 3. LED light color: white is recommended, because it is dazzling and better than warm.

 4. Burning time with different batteries. If pursue high light, the LED flashlight’s burning time powered by different batteries varies. When LED power consumption 3W, current 750MA, various lithium batteries following the flight time: 18650 life time in three hours; 16340 or 14500 life time of 1 hour; 15266 or 10440 life time of 20 minutes; and the pursuit of medium power common good, to use all the small shop to buy ordinary batteries. With rechargeable AA batteries, the discharge current is about 2A, the life time of about 1 hour; with a capacity of 2200MAH high quality alkaline AA batteries, the discharge current at around 1A, about life in the last two hours (if current 2A discharge on the very economy, often only highlight for half an hour); garbage AA batteries, 1A discharge uneconomical, preferably 500MA current discharge, the life time can be up to about 2 hours.

 5. What circuit: few people may consider this factor. In the flashlights, some use constant current circuit, some do not. Here, we recommend the first one for it can ensure constant brightness until the battery is going to run out.