Here is a link from Flashlight- Forums.com A good place to go to pick their brains on flashlights.
Re: LED real life vs theory
Its simple really. LED lifespan is DIRECTLY proportional to HEAT and "how hard" you push them.
The phillips bulbs are so bright because they hammer them with POWER which greatly shortens their lifespan. (if you get 15k out of one I will be impressed)
but my 12watt LED tubes that I "detune" to 89volts so they consume 3.5 to 4.0 watts and are never more than 5' above ambient room temperature have been going for 7 years and are still chugging away like they are new.
the largest problem is LED run at "max" rated power but with totally inadequate cooling. typically (could be different today my knowledge is a few years old) LED's do NOT like anything over 100'F (white led's)
they also need 9cm/2 of passive cooling surface area PER WATT of consumed power.
so that 5watt LED needs 45cm/2 of cooling surface area.
if you do not have 45cm/2 of cooling area you need to REDUCE the power until its within the limits of your cooling area.
or you need to switch to active cooling (fans etc..)
many of the cheapo chinese LED bulbs are rather nice but they run them "too hot"
basically GRAB the bulb after its been running 15 mintues.
Does it feel warm? EVEN A TINY bit warm? if so its TOO WARM (unless its the heatsink thats warm that is ok)
anything "warm" to your touch is by definition "warmer" than you. your skin temp is around 90-95'f
so anything that feels "warm" to you is likely already over 100'F ie BAD.
part of the problem is people want "point source" lighting. IE 60watt bulb lighting up a room.
with LED this is hard to do because the light is very directional. the PROPER way is to use the lowest power LED bulbs you can and "spread them around"
to get brightness you keep adding more LED's until you have sufficient brightness. also if possible REMOVE covers and shades so you don't waste lumens.
I light my front porch with 3 .9watt LED's its VERY bright. brighter than the 2 13watt CFL's because those CFL's were inside a translucent glass enclosure. 90% or more of the light was "wasted" before it hit anything for you to see.
I got a 3 bulb vanity fixture and put my "bare" led bulbs into that. this way I USE almost 100% of the light I emit.
sadly its a gamble. you have to just "buy" some plug them in and run them 24/7 for a month or two and see what happens. if they hold up you might have a good one. (2 months if nearly 1500 hours)
any change in color or brightness and its likely a dud avoid those.
for starters what you want is the large "half ball" LED's in the 3-5 watt range where the bottom half of the bulb is a ribbed finned HEAT SINK (careful some look like metal but are plastic AVOID)
you especially want to avoid the "par" style bulbs. that look like those "glass cones" you use outside? I have never had ONE SINGLE ONE of those work right and not burn out very rapidly.
contrary to popular belief LED's produce a LOT of heat. 80% of the power you put in comes out as heat (compared to over 98% for incandescents) so it is a big improvement.
BUT unlike incandescents the LED's CAN NOT TOLERATE that heat. you must dissipate that heat away from the LED emitters or they will DIE.
the little .9 to 1.1 watt balls at walmart $7 are also proving very good so far. I had one going 4 months over 3000 hours no issues so I am hopeful :-) not much of a heat sink but it has to dissipate less than .7 to .8 watts of heat so it seems to be enough. and the light is nice bright and warm especially when you cluster them.
stay away from bulbs of america units. I LOVE their 1.5 watt glass ball units (use them in the bathroom) but they just do not last.
which brings up the last problem.
when you make a 7000 hour CFL the other components don't matter much.
but when you have a bulb that can go 50,000 or 80,000 or 150,000 hours suddenly the LIFESPAN of the OTHER components in your bulb become important.
when that cheap 2 cent resistor or capacitor blows so does your bulbs. sadly they are used to using "CHEAP PARTS" in their stuff figuring the something else will fail first.
well now with LED's suddenly the lifespan of those cheap components becomes important.
worse the primary manfacuters who CAN make good bulbs (Ge Phillips etc..) WILL NOT because it is not financially equitable to make a cheap long lasting 80,000 hour bulb.
they would rather make stupid $60 12-13watt hyper powered LED's that won't last as long OR save any power over the $1 13watt CFL you can get from dollar tree.
you would have to be dumb to buy that bulb when the $1 CFL uses the SAME power makes the SAME light and has nearly the SAME lifespan as the $60 LED bulb.
nuts. :-) thats greed for you.
