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View Full Version : I am confused

jimbo
08-20-2008, 10:49 AM
or my math is not working.

Looking at an Eveready Hardcase LED flashlight. It uses 2 AA batteries ( series ). Has 3 led bulbs, which is says are one watt each. They claim a run time of 17 hours. I understand that a AA battery has a capcity in the range of 2700 to 4000 maH depending on type and grade. This does not seem to add up to running 3 watts for 17 hours! Are the LED bulbs really one watt each, or does that mean the "equivalent light" of a regular one watt bulb??

TigerDriver
08-20-2008, 12:53 PM
or my math is not working.

Looking at an Eveready Hardcase LED flashlight. It uses 2 AA batteries ( series ). Has 3 led bulbs, which is says are one watt each. They claim a run time of 17 hours. I understand that a AA battery has a capcity in the range of 2700 to 4000 maH depending on type and grade. This does not seem to add up to running 3 watts for 17 hours! Are the LED bulbs really one watt each, or does that mean the "equivalent light" of a regular one watt bulb??

Who knows? Incandescent sources are "volumetric" radiators while LED's are "point" radiatiors. Here's a good article (http://www.lite-knight.com/lumencalculator.htm)on the subject.

jimbo
08-22-2008, 09:22 PM
I put in fresh batteries, and connected a meter in series. The flashlight draws approx. 50 ma. That explains the 20 hours ( draw-down test confirms 20 hour run, but with some rests periods. Will not run 20 hours at one sitting. )

Interestingly, this AA light has 3 LED in it, and draws 50 ma. I actually have a second "penlight" version, uses AAA batts and has just one LED. It draws about 260 ma! And the run time is much less than the other, but well in excess of the one hour which Eveready told me on that one.