Streamlight Jr Luxeon - how efficient is it?

I somehow suspect, not very. It doesn't run for that long on alkaline batteries, and only about 2 hours on NiMH because apparently it is drawing very high current loads. This is consistent with Duracell's graphs for putting an AA cell under a one amp load.

First, a few numbers. Their specsheet mentions a 1 watt Luxeon, and LumiLEDs says drive it at 350mA max. A Vf of around 3.2V (estimate) would give 3.2 x 0.35 = 1.12W. They are using a regulated circuit, which I assume is 70% efficient. In total, the LED, plus circuit should draw 1.6 watts from a 3 volt alkaline source. 1.6W / 3V = 0.533 amps from the AA cells. According to Duracell, the cells should last more than 3, almost close to four hours at 0.5 amps. Using nickel metal hydride and its more constant discharge curve simplifies it even more, assuming you have good 2100mAH cells fully charged, 2100/533 = 3.93 or close to 4 hours as well. 2 hours is more consistent with a 1A drain.

What's up? Is the Luxeon being driven at twice its rated current, which would explain why? That would warrant its battery drain and justify it because you get more light, so it is worthwhile. However, if they are truly driving at 350mA and somehow the battery power is being burned up elsewhere, I think I'll go grab a sandwich instead /ubbthreads/images/graemlins/smile.gif

I believe it is overdriven. From the comments I have read, I think it is competitive with some of the sandwich options in terms of brightness and runtime, so that would indicate similar overall efficiency. But that is not really a reason to buy the Jr. over a sandwich.

None of this type of light is really a runtime champion anyway. The UK eLED is, though.

Hmm.. true. The UK eLED is the other one I have an eye on, and the 11 hours runtime is amazing and has been independently verified by many here. What's not so amazing is they claim 30 lumens. I wonder how they get that AND 11 hours, and besides, one of their "38 lumen" lights came in about equal with my E1e+MN01 in terms of brightness. 38 lumens should be a heck of a LOT brighter.

Roy's runtime chart bears out the Streamlight runtime claims. The LED Museum tested the Streamlight at 628mA current drain (from the battery end).. that should give us four hours, oh well. I suspect I might have to buy one of these and do some testing myself. (excuse to buy another light, HA! /ubbthreads/images/graemlins/sssh.gif)

I think the Streamlight is more likely to achieve its 30 lumen rating, because it's overdriven. There has never been more truth in the saying "The candle that burns at both ends burns twice as bright, but half as long".

My approach would be to buy the Jr., put NiMH batteries in it and then runtime is no longer an issue. At least not a cost issue.

the uk 4aa eled is not 30 lumens

The UK 4aa eLed is no where near 30 lumens. Its about 1.5 times as bright as a stock Mini-mag bulb. So, on Maglites website the stock mini-mag bulb is rated at around 8 lumens IIRC....that places the UK 4aa eLED at around 12 lumens.

Its a very useful 12 lumens though. The sidespill is very bright on my UK 4aa eLEDs, and it gives a very nice flood pattern with good tint and good beam quality. The little tiny hotspot beam on the UK 4aa eLED is about the size of a pencil eraser--this flashlight is meant for flood, NOT throw IMO.

I saw a review of it here:
http://www.imagometrics.com/FLReviews/FLR_SL_Jr_LED.htm

^They do a really good job of reviewing lights, IMO.

Kevin,
I have taken apart a few SL Jr. Luxeons and they run a voltage of K or 3.51-3.75 volts. Just for ease of math, lets go with the strict average of 3.63 volts and drive it at 350mA or 1.27 watts. The voltage of NiMH batteries is 2.4V so it needs to boost the voltage by 50%.
Say the NiMH battery is 2100mAH but as we know, it will be less than the rating because of the amp draw. For ease of math, say the battery puts out 2000mAH. So, 3.63/2.4=1.5 1.5x.350 = .525 amps if the regulator is perfect. Say the regulator is 80% effecient, the amp draw rises to 656mA. This would give a three hour run time and under test, they get 2.5 hours.
If you run it at around 400 to 450mA, the battery runtime is about right. My original BB500 would gulp alkalines in around an hour and a half, I figure it was running a K bin for voltage. Draw past half an amp on an alkaline AA, the life of them dies quickly. All hail the NiMH!

CPF OWNS /ubbthreads/images/graemlins/bowdown.gif trust it to get me the truth when I need it.

I figured the UK eLED is not 30 lumens, I was just quoting their specsheet. It's a good light though if you need extreme runtime. That Streamlight review is very well done. The pics say a lot about the light that I otherwise wouldn't have picked up from just the datasheets.

BentheadTX: thanks for reminding me that NiMHs don't do 3V. I should stay away from hardcore maths when extremely sleepy /ubbthreads/images/graemlins/smile.gif that probably explains most of what we are seeing. I've been reading about your very positive experiences with the BB500, and I'm tempted to just buy the sandwich in the end anyway since I have some TV1Ks here that I could use. Wherever possible I use NiMH cells in order to cut costs and to get better runtime especially on high drain devices.

I recall from one of your posts that you mentioned the BB500 still makes the Streamlight look "Jr".. it's that much brighter? Since this light is going to be NiMH anyway I'm looking for all the brightness I can get.

Is the Kroll mandatory for the sandwich or can I still use the twist on-off action if I don't epoxy the head down? Did you have to do a lot of cutting to get the SO17XA to fit properly? I'm planning to use the reflector if I can because of what I've been hearing about the performance gains. No sense in letting the NX05 optic (intended for LDs) eat up the photons.

Kevin,
Trying to keep all the variables straight with flashlights can cause brain damage initially. /ubbthreads/images/graemlins/crazy.gif I have been messing around with Wayne's sandwiches for two years so I have adjusted to the damage.
For non-flashaholic use, I recommend the SL Jr. over sammies for several reasons. My BB500 R2H requires a little maintenance every now and then to keep it running perfectly. The sammie must be taken out quarterly and corrosion on the part that grounds to the light (the top) must be cleaned with an eraser. Do the same with the positive contact and slide it back in. The o-ring to hold the sandwich in makes this much easier.

I have never used a minimag with twist motion to turn it on and off, I prefer not to make and break the ground connection since I am paranoid about corrosion and wear. Having the reflector twist on top of the emitter should eventually stress the leads and that can't be a good thing. The other point is once you have the SX17XA centered with an o-ring, I prefer not to throw it out of alignment. This goes for my Fraen LP equipped BB500 R2H bicycle helmet light.

The reason the BB500 R2H spanks the SL Jr. has to do with the bin code and it might be driven a little harder. The R bin puts out 40-52 lumens at 350mA with the H bin meaning a low 3.03-3.27 forward voltage. The PXOK bins in the Jr. equates to around 23.5 to 30.6 lumens at 350mA with a forward voltage of 3.51 to 3.75. The R2H puts out more light with less electricity for a longer runtime.

The SL Jr. Lux uses a low dome which does not throw as well as the R2H high dome. If throw is your thing, a high dome with Fraen LP for a big hotspot/no spill or high dome with SO17XA for smaller hotspot/good spill would be better. As you can see, an R2H high dome driven at 500mA through reflectors make for a very bright and efficient light.

As far as cost goes, my BB500 R2H sandwich ran me $60, the SO17 was $6, Kroll switch was $4.50, mineral glass was $1.50 and minimag ran $8. Throw a couple of bucks for shipping/tax and we have arrived at over $80 /ubbthreads/images/graemlins/eek.gif It is well worth it to me as max light with max runtime is important for a bicycle helmet light.

A problem both the sammies and SL Jr. Luxeons have is heat, they both get very warm if running without airflow or sinking heat to your hand. There is a solution though if you can handle a slightly longer light with a thicker (and heavier) barrel. Elektrolumens is coming out with the XM-3 2AA which is a LuxeonIII running at 600mA through a reflector. It comes with a clickie switch and with the increased mass, should be cold running. It will be waterproof, probably beat the hell out of anything and has a clip on the side. His pre-sale price is $39.95 which puts him in the best light for the bucks category.

The XM-3 is easily modified with your TV1Ks, everything is easily replacable with the light so mod away! I will be going to the desert in a week so I will order mine when I get back in January. No more being careful with my EDC, the XM-3 has 1/4" thick barrel walls! If the larger size and heavier weight does not bother you, pass on the BB500s/SL Jr and go with the XM-3.

Very impressive analysis of the available options /ubbthreads/images/graemlins/happy14.gif

I can understand your satisfaction at having found what could be your perfect light for your specific needs. I feel that way about the KL1 myself - it fills every imaginable role, except that it does not run on AAs. I figured instead of getting a power pack for it, I'd check out other options which enabled me to run AAs and incorporate a Luxeon emitter. It's not going to be a primary light, more of a backup. I also considered giving one to a friend who could use one, your info about the maintenance required for sandwiches is a crucial deciding factor. I agree that the non-flashaholic would balk at having to conduct periodic maintenance. When I owned nothing more than Maglites, the lights NEVER got maintained.

My current AA light is a Terralux Ministar2, and I'm quite disappointed. Of course, they quoted the maximum LED specs on their specsheet, 22 lumens for a side emitter. After the 15-lumen-rated KL1 stomped all over it, I kinda disagree. The side emitter is quite green as well, and the beam's got lots of artifacts. Ready to step up to something more powerful. I may give the Sandwich a shot for myself, I'm buying the bare components since I have TV1Ks and perhaps more confidence in my soldering skills and Blue Tack than I should otherwise have /ubbthreads/images/graemlins/tongue.gif

Very good point about the Kroll clickie, I've just added that to my parts list, and the SO17XA reflector. I've been itching to try that for a while since I already have an NX05 in my EDC. For pure throw, that's best left to the large Mags when I really need to reach out and poke something. Thanks for all the suggestions, now I know what to decide on.

You're headed back to that big sandbox again? Take care and stay safe /ubbthreads/images/graemlins/smile.gif

Kevin,
Found the perfect chart to explain the differences between alkaline, NiMH 2300 mAH and lithium AA cells. Stole this link from kj's site were he did in depth analysis on run times for different sandwiches.

The most interesting is the BB400 R2H (really 416mA if your anal) He gets ruler flat current regulation for 55 minutes at 520 lux until it dies to 85 lux at 75 minutes. That chart is for alkaline batteries. Sanyo 2300mAH NiMH AA cells give 180 minutes at 550 lux and then die quickly to 120 lux at 190 minutes. The lithiums made it to 185 minutes at 520 lux.

I have Sanyo 2300mAH batteries and they give over three times the run time, and a little brighter also! OK, the lithiums beat it by 5 minutes but I bet the new Sanyo 2500mAH NiMH cells will be the runtime champs on any AA chemistry. This is one of those rare times that the least expensive solution is the best one.

Here is the link to the chart:

http://www.obaq.tv/cpf/images/MiniMag_Mod_Badboy400-R4H-2AA_Runtime.png

I came across that site too while searching for instructions on how to build sandwiches. The BB's regulation curve, or rather lack of curve, is amazing. Where I am, the Energizer L91s are available at regular supermarkets and thus at regular supermarket battery rates (not the best in the world, really). I could get three NiMH for the price of two L91s - even if I was to throw them away after I was done, I'd still save money. Looks like I'm on the right track with the sandwich /ubbthreads/images/graemlins/smile.gif

Hm.. the XM3 looks really sweet, but I was trying to get an idea of its size, and it really is huge IMHO. Based on the measurements on the Elektrolumens webpage, I get the idea that it is a Surefire 6P with two extra inches. The 1.25" bezel and 1" diameter sure sounds exactly like the good ole 6P. 7 inches is also a bit long. I may go for the sandwich since I already have the miniMag and it is not intended to be my main light - the KL1 does that job.

Still, I can see why you guys like it, it's built to last forever, it even has a Surefire-ish look, and the quarter-inch of metal that the 6P has. It's great value, and for those who need Luxeon power for hours a day, NiMH makes a great value even better. It costs less than the KL1 conversion head ALONE. I want one, but.. $$ and size /ubbthreads/images/graemlins/smile.gif

I just bought a Streamlight Luxeon Jr. from B/S/T. This is the first one I've had so I can't say for sure, but I think it's a dud. The output is no more than 15 lumens. It's less bright than my Surefire KL1, Arc LSHF-P, and Streamlight Luxeon Tasklight. With a fresh set of alkalines it draws 600mA.

Nikon, I think you did get a dud. My Jr. is brighter than mt SL TL-2 LED, and my SL Task-Light.

It rivals my new Gerber three watt in brightness.

I'd send it back.

"Trying to keep all the variables straight with flashlights can cause brain damage initially."

Well, that certainly explains a lot! Is it reversable? Better to back off, or plunge right in? Should I take notes maybe? Keeping up with the entire forum is not only time consuming, but definitely mind-boggling as well. Being so addictive, I do hope it's not that damaging. After the '60's and early '70's, there doesn't seem too much left to play with, know what I mean?

Oh yeah, I forgot -- my Streamlight Luxeon Jr. runs for hours on NiMH, but is more suitable for close-up with a nice even white beam. The Tasklight Luxeon with three AA's is a little brighter, but the throw is much better. It can be focused somewhat and is direct driven, whereas the Jr. is neither. BTW, that clickie tailcap is usable on both lights.

Nikon, I sent you a PM regarding the Luxeon Jr. I'm sorry about this, It was also my first one so I guess I didn't know what it should be like. I wonder if I can send it back to brightguy where I got it, or send it back to Streamlight??? Problem is there really is no problem, just not as bright as it should be, whatcha think??? Doug /ubbthreads/images/graemlins/smile.gif