(s)MJLED efficency; still a good choice?

[Buck91]

I was thinking, since i just cleaned and lubed my MJLED (possibly SMJLED, not sure anymore!) 2xAA minimag, how does the SMJLED drop-in compare for runtime with other, newer leds out there? I know these cree's and other such high power leds are supposed to have great efficiency, but most people utilize this by shooting for high output. Would they be a good choice for a low-output light as well? If so, how would that compare to the ubiquitous SMJLED?

 

[jasonsmaglites]

great question.
do the little leds found in most cheap lights match the efficency of the luxeons?

that's what i've always thought.
so, the runtime is good if it's dim basicly.

 

[Marduke]

great question.
do the little leds found in most cheap lights match the efficency of the luxeons?

that's what i've always thought.
so, the runtime is good if it's dim basicly.

5mm LED's can range from 25-100 lm/W, with most of them being around 50-75 lm/W when driven properly at ~20mA. When driven even lower, some approach 100lm/W, and when driven higher (around 100mA) the efficiency drops drastically, by 1/2 or 1/3 as much as at 20mA.

The better bins of Cree and Rebel can do ~100lm/W these days, driven at 350mA

 

[LEDninja]

From jtr1962's White LED lumen testing thread:
http://candlepowerforums.com/vb/showthread.php?t=89607&highlight=jeled
SMJLED
Efficiency at 20 mA is 87.8 lm/W
Once past 20 mA it surpasses every 5mm white LED tested to date in efficiency.
At 100 mA efficiency is 57.2 lm/W.
jtr1962 also has reviews of the Cree XRE etc. in posts towards the end of the thread.

The main advantage of the MJLED/SMJLED is the ability to push the LED legs closer and insert into the bulb socket of a minimag, something that you can not do with a Luxeon, Cree XRE etc. The Vf is low enough that 2 alkalines or primary lithiums can direct drive it.
Detailled instructions here:
http://home.mchsi.com/~lambda_lights/smjled.htm

For more info:
SMJLED confusion explained
http://www.candlepowerforums.com/vb/showthread.php?t=128865

MJLED cut uncut
SMJLED cut uncut
SMJLED module with boost circuit allows use of NiMH batteries. Also more consistant output.
SMJLED Solitaire
SMJLED PR2 base

If you need runtime and not uber brightness the various MJ leds are a good choice. Properly driven it gives 15 lumens which compares favourably with an Arc AAA of that era of 3 lumens. Today with lights starting at 60 lumens it is no longer considered bright, but hardly any of today's bright torches will gie 20 hours at the max srtting.

 

[LedLad]

They MAY be very 'efficient' but they are, IMHO, basically worthless other than as a VERY weak candle during an at-night power outage. They simply don't have the overall output to be very useful as a flashlight and the "beam" is so diffuse that you get no distance light at all.

My $.02

 

[Buck91]

Thanks ninja, good info.

Ledlad, I have one in my minimag and find is perfect for its function. If I need a brighter light I have various cree and rebel lights as well as my magled. I'm not a lumen junky, just need the right amount for the task at hand; and the task-at-hand for this minimag is decent output with extended runtimes.

 

[LedLad]

for this minimag is decent output


Of the entire above, this is the only part I will take exception with...if you are happy with your mj mini then kudos but I personally find that it's output is nearly useless for anything except what I stated...a small amount of general illumination in total dark conditions, thus limiting it overall. But then my hatred of the money wasted on the POS magled mj drop-in is well known. :devil: