Originally Posted by
turbo1889
I also have an older LED flashlight of the high quality Pelican brand name that is worn on my belt at my side in a leather pouch every day that uses 2@AAs and puts out about 90Lm or so that is a couple years out of date but is reliable and uses NiMH rechargeable batteries that I have lots of around my place......It is, however, outdated at this time and the equivalent current flashlight from Pelican is much better. It is certainly outdated.
Outdated how? It suddenly doesn't do what you bought it for? In spite of being reliable and still having a 90 lumen output? I've put about nine 'new and improved' LED flashlights in the garbage myself since buying that Pelican because .... they simply fell apart.
Originally Posted by
turbo1889
....... As to 1,500Lm being the upper limit there are single emitter LED units currently that far exceed that for other applications. One that I know of is basically and LED version of those big lights they use for football fields that uses three emitters inside the reflector housing and the whole light unit is rated to put out 15,000Lm and it doesn't take a rocket scientist to divide that number by three and realize that each one of those emitters is rated to put out 5,000Lm per emitter which kicks the pants off of any single emitter I've seen in any flashlight. Granted they are physically larger in size and I'm certain are pulling more wattage but that means that right now the technology already exists to get 5,000Lm or more out of a single emitter so there is certainly room to grow for the LED flashlight market. All that of course assumes that something even better then LED's doesn't get invented that is even better at converting electrical energy to light energy with even less wasted energy. Electronics technology is a rapidly developing field and stuff does get outdated in only a few short years.
Think you both misread my statement AND ... I was dumb enough to type too fast and as a result was off by a decimal point. I stated the upper theiretical limit for LED technology was estimated at 1,500 lunens / watt when in fact its only 150 lumens / watt. Currently as far as I know the leading lumens / watt LED street-lighting spot is held by these people:
http://www.emersonindustrial.com/en-...Luminaire.aspx
Its a multiple emitter array that puts out 13,000 lumens using 127Watts or 102 lumens / watt.
Last time I checked, any single emitter put out by Cree or Seoul Semiconductors was well below 115 lumens / watt and if you have a link to anything different I'd definately be interested.
The big problem the presents itself with increased wattage is heat dissipation. That happens now with multiple emitter lights and won't change even if the light was a single emitter as long as the lumens / watt doesn't change radically. Currently flashlight and bike light manufacturers are both building insufficient heat sinking into their products to permit extended use. Some of the products literally get too hot to hold after several minutes on high. Specialty units for commercial lighting have fans built in. They probably wouldn't make great flashlights or bike lights. The Foursevens Maelstrom XM18 might put out 15,000 lumens, but only for an hour and a half, weighs about 13 pounds and takes two hands to operate. Not to mention the $2,500 price tag.
Originally Posted by
turbo1889
I've got another thread that I started on that (the LiFePO4 thread further down the page) and I'll get back to this project lumenson that thread once the flashlights arrive and I figure out if I can successfully power them off of just a single 3.2V cell or if I've got to double up and run 6.4V to get them to work. I'm really hoping that a single cell arrangement will work since that is the simplest set-up possible with zero balance issues ~ KISS engineering reliability.
I've noted that and already commented on that thread. Your best bet would be to use a source that pre matches batteries for capacity before building their battery packs. Since even when 'empty' a lithium cell is 60% charged (non-usable), the effects of any cell imbalances won't affect the life expectancy of the battery pack. Things would be different if you were using a 6 or 10 cell battery pack. I am interested in how you make out and will keep in touch.