# Gemini Duo vs MagicShine MJ-906 vs CygoLite 1300 Extra



## rsilvers (Aug 23, 2015)

I am not sure which I should want the most. I may do helmet or bar mount.

2016 Duo has wireless remote, which I really like. Until it is proven at 1500 lumens, I am going to assume it is 1300 lumens for 3 hour run-time.

CygoLite 1300 xTra is 1300 lumens for 3.5 hours of claimed runtime. No remote and costs about $35 more.

MagicShine MJ-906 seems to have comments that it wastes light by sending it to the sky. Has wireless remote. Has wireless tail-light. About $20 less than the Gemini. No one has said how many lumens it is (except for the factory lie).

I am not sure what to do.


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## indebt (Nov 8, 2009)

I have a soft spot for the Cygolite Triden X as I have some really good night riding memories years ago when I first started night riding. I was using the Triden X Extra 600 lumen version and it held up to countless hours of abuse.

That been said,,,,Out of the three your considering my choice would be the Duo. I think it is the most versatile of the three and good value. A bit bias here as I'm not a big MS fan and that light I think may feel a bit big on the lid as it would sit rather high as you were considering using both bar/lid applications. My 2cents.


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## rsilvers (Aug 23, 2015)

Thank you. A real nice thing is that the Duo is programmable so you can pick what modes are in the cycle.

Please vote on the poll.

New video out:

Beam seems very tall - like a portrait format - more tall than wide. And the flash is not an attractive flash pattern and always in the modes as far as I know.


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## indebt (Nov 8, 2009)

I actually like the beam pattern in that video for single track and yes although not 5000 lumens clearly bright and best output of the three. If you were looking for bar mount only this may not be a bad choice if pure output was at the top of your list. Sorry not trying to make things more difficult for you but IMO if your planning on both bar/helmet uses the Duo!!


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## rsilvers (Aug 23, 2015)

One thing is likely clear - the 906 has more going for it than the CygoLite. Probably 2x the output, wireless control, much lower price, and a wireless controlled tail-light.

I think the answer is - head mount - the Duo. Head or bar mount, the Duo. Bar-mount only, the 906.

My reason for thinking the 906 is better for bar-only mount is that (as I saw someone here estimate) if the 906 makes 60% of its rated output. That would be 3000 lumens. A figure normally reserved for $400 lights (NightRider Enduro Pro Remote 2800 is $400).

The Duo is probably 1350 or so. The Duo costs significantly more, and has a 4-cell pack rather than a 6-cell of the 906. So if one is going to only bar-mount, it seems like you get a lot more with the 906.

If I get that, I can head-mount my CygoLite 550, or get two of those $10 Amazon USB lights (I have one already and it is fine but could be brighter), 3D print a dual-head mount for them, and plug them into a JuicePack and have ~1000 lumens for $20 to light up what I am looking at while the 906 floods the space in front of the bike.


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## tigris99 (Aug 26, 2012)

Rsilvers:



Quick clarification. The reason a beam looks long and narrow (what you take as tall) is that's its pointed at a downward angle. The beam is actually round (like all lights) but when you point any light at an angle from the surface your illuminating (except parallel or 90deg) the beam pattern becomes elliptical in appearance. This is normal properties of any focused light source no matter what it is.



Some that dont appear as long out front use a cut off of some sort, the beam still elongates just not as noticeably. Like either the face plate being designed to block part of the light that goes "up" or optics like wide angle/elliptical. Though those optics still have spill that goes out at all angles, the hot spot is more wide than long even when pointed at an angle to the surface.



Im with others on the Duo (on my phone can't do a poll). You really dont need a ton of lumens, that thinking is why Chinese lights lie, "lumens sell". 



Also look at trade offs. The 906 doesn't get any better run time, you have a pack that weighs 3/4 of a pound easily, a large and heavy light head.



I ride with 1200-1500 lumens on the bars at speed. 1200 on the lid. Too much more and shadows get washed out, get too much glare in moist conditions. But I ride tight and twisted midwest single track.



Dont worry so much about lumens, worry about how their used and how much weight you want to add to your bike and head. This is also where the duo come is good, dont like the beam pattern, optics to make it what you want are widely available and cheap. Takes all of 2 minutes to change them.


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## rsilvers (Aug 23, 2015)

Duo is clear winner for head-mount. I am not so sure for bar mount. It would seem like I would want two Duos or one Titan on the bar (or one 906 for way less money).

As for the 906 has no advantage in run time, I think it does - because for any current draw, the 6-cell battery will likely give more run time. That could matter for 2 hour ride in the winter.


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## Cat-man-do (May 16, 2004)

I would go with the Gemini Duo as well. Very nice looking set-up. Programmable modes and switchable optics. If they offered neutral LED's I'd think about buying one myself. Glad this thread was started. I didn't know the new Duo had a wireless remote.

A quick note about wireless remotes: For years I've been wanting a lamp with wireless remote for the helmet. Now that a handful of manufacturers are starting to make them a thought occurred to me the other day; How well will the Wireless remote work in cold weather? Don't be surprised if the WR doesn't work as well in cold weather...Why?....Because likely they are using coin or button cells. Likely they also have a small ( parasitic ) drain which will also limit the life of the batteries. Couple that with cold weather and I have a feeling the wireless remote is not going to function real well when it gets cold. Then there is the possibility of RF interference if you already use a lamp on the bars that has a PWM circuit. Yes, all this speculation on my part but for sure I already know that coin cells don't like cold weather.


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## rsilvers (Aug 23, 2015)

I have a question about people asking for natural white. I am confused as to why. I think when people say they want natural white, they really say that they want a higher CRI.

No one complains about Audi headlights, and they are 5500 color temp.

CRI is what matters. Color temp should not matter as your eyes will adjust. Overcast daylight is 7000.

If I am correct on this, then we should talk more in terms of CRI and not color temp.


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## rsilvers (Aug 23, 2015)

From Cree:

Typical CRI for Cool White (5000 K – 8300 K CCT) is 65.
Typical CRI for Neutral White (3700 K – 5000 K CCT) is 75.
Typical CRI for Warm White (2600 K – 3700 K CCT) is 80.

Pretty sure you guys like NW because the CRI is 10 more. Cree has an 85 and a 90 CRI option also.

Agreed a CRI of 65 is garbage. I bought all 90 CRI tubes for my garage and basement lights. They cost at least 2x as much, the are still cheap enough that I am surprised more people don't do it (I don't think many people know what CRI is or shop for it).

80 CRI is the minimum acceptable for home illumination. In fact, you can't get an energy-star rating on a light bulb unless it is 80 CRI or more.

A mercury vapor street light is about 49. Those yellow low pressure sodium parking lot lights are -44!


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## Cat-man-do (May 16, 2004)

rsilvers said:


> I have a question about people asking for natural white. I am confused as to why. I think when people say they want natural white, they really say that they want a higher CRI.
> 
> No one complains about Audi headlights, and they are 5500 color temp.
> 
> ...


It only helps to talk about CRI if the number has a reference you can personally relate to. Otherwise it just makes things more confusing. If you go to this website you will see there are a handful of color rendering scales. Doesn't really matter because the CCT scale ( correlated color temperature ) is still used to help determine CRI ( depending on whether it is above or below 5000K ). In short, you can't have one without the other.

You are right though, CRI would be a more accurate scale but few manufacturers of lamps or LED's seem to use this scale. Long before LED's came along halogen bulbs were rated by CCT ( the Kelvin temperature scale ). The LED manufacturer Cree still uses the CCT scale to ( broadly ) rate their LED's. Cree also uses some ANSI standards as well but truthfully just looking at all the ANSI rating numbers is mind boggling / very confusing ( and that's just under one CCT rating! ).

Anyway, numbers are just numbers unless you KNOW what that number means to YOUR EYES. Not all people see color the same so a set value point on a scale is only important to the person doing the seeing. What number works for one might not work for another. This is true regardless of what color scale you use.

All of this said; Once you add high lumen outputs to the mix, confine them to a small area ( like with bike lights )....THIS WILL CHANGE EVERYTHING!. The iris of the eye will either constrict or dilate to adjust to the intensity of the local lighting. Too little light and and colors seem to fade. Too much light and colors just seem to blend more together. Finding the perfect mix of CRI ( or CCT ) led tint, lumen output and beam pattern is what it's all about when it comes to bike riding at night. If you're looking to dial in the perfect set-up, finding the right LED bin tint is only a third of the equation.


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## tigris99 (Aug 26, 2012)

Actually there is SO MUCH MORE than just CRI that is involved here. Apologies but im not going to type that whole thing out. But actually pay attention to what your trail looks like for color detail and shadows on an overcast day vs clear sunny day. An actual true examination with your own eyes will explain everything. Colors are dull, shadows are minimal, just sit there and stare at everything, take some pictures and compare. Youll see what you loose and why we want neutral light that is more natural so clear daylight.

BTW all of us recommend these things for a reason, we live and breathe LED lights and night riding. SOme of us have more bike lights and flashlights than we will ever care to admit. Its alot of time and research to learn all this stuff. Were happy to help you learn if you want to know. BUt first thing before numbers like your quoting is to learn the principles and variables behind it all. Then you can use numbers to get down to the finer details.

And I hate audi headlights and anything like them. In the city their tolerable, where I live which is rural, I want to bust ever set of them I see cause their blinding as hell. Oh and I have high cri daylight bulbs in my basement and garage lights as well, but low nuetral/natural white. Not high color temp crap.


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## Cat-man-do (May 16, 2004)

tigris99 said:


> ...And I hate audi headlights and anything like them. In the city their tolerable, where I live which is rural, I want to bust ever set of them I see cause their blinding as hell. Oh and I have high cri daylight bulbs in my basement and garage lights as well, but low nuetral/natural white. Not high color temp crap.


He, he,... I forgot I wanted to comment about the car LED lights too but forgot cause it took me so long to write the last post. Not going to pick on Audi per say as when I'm driving at night I can't always pick out the make or model of a vehicle. Overall though, when it comes to LED car headlights... I absolutely hate them. Most of them _are_ blinding as hell and I'm seeing more and more of them everyday ( unfortunately ). I hate the super bright halogen bulbs as well but only because they are so bright-white. ( lets not even talk about the idiots using the stupid bluish bulbs) 
( Please note here that I drive at night as part of my job so I see this stuff every day ).


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## tigris99 (Aug 26, 2012)

I work nights......and ya dont get me started on the "cool blue" headlights either, OMFG. I stopped and cussed out a stupid teenager that thought it was cool to drive around town with them on high beams all the time. The worst of the ones with these new headlights that I want to bust out are the fraking pickup trucks, their damn headlights are right at my eye level or right in my mirrors.

HIgh powered headlights are good on open road without on coming traffic, especially here where there is deer like crazy. But ffs they need to come up with a way to mellow them out when on low beam.


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## Cat-man-do (May 16, 2004)

tigris99 said:


> I work nights......and ya dont get me started on the "cool blue" headlights either, OMFG. I stopped and cussed out a stupid teenager that thought it was cool to drive around town with them on high beams all the time. The worst of the ones with these new headlights that I want to bust out are the fraking pickup trucks, their damn headlights are right at my eye level or right in my mirrors.
> 
> HIgh powered headlights are good on open road without on coming traffic, especially here where there is deer like crazy. But ffs they need to come up with a way to mellow them out when on low beam.


Well...I try not to let it get to me too much. Good chance the next vehicle I buy "might" have LED lamps...what'a'ya gonna do, not buy a newer car? When in Rome....

For the time being if a vehicle approaches me from behind with Super bright lights I just readjust my mirrors. On-coming traffic though, not much you can do but try to look away and try not to let it get to you. Anyway, this is one of the reasons why I don't understand the fools who complain about bright bike lights. Who cares about a stinking bright bike light on the side of the road when a quarter of the newer cars are using Super bright twin LED headlights, shining them right in your face and following you for miles!


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## rsilvers (Aug 23, 2015)

Cadillac seems to have the best headlights now.

The new Audi ones will mask off light going to where other cars are:

Audi Pixelated Laser Headlights Light the Road and Paint It Too - IEEE Spectrum

They are not legal in the US though due to outdated regulations.


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## rsilvers (Aug 23, 2015)

For anyone wondering, the actual light output of the MJ-906 is 3200 lumens according to test data referenced here:

Magicshine MJ-906 Headlight/Tail Light set with Wireless Remote Switch ? Action-LED-Lights

So it has 2.5x the output of the Gemini DUO and 1.5x as much battery capacity.


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## Cat-man-do (May 16, 2004)

rsilvers said:


> ....Cadillac seems to have the best headlights now.


Yeah, I remember having a Cadillac pass me late one night...Their headlights did light up the road like no other vehicle I have yet seen. I was annoyed and impressed at the same time.

Thanks for the info on the MJ-906. Looks like Magicshine is _WAY_ overstating their actual output! It should still make a good bar lamp although at 3200 lumen I really don't think anyone needs that much light coming off the bars. I doubt the beam pattern is designed or would work well for helmet usage. If you're into high output, cool white bar lighting this lamp should give you more than you need off the bars.


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## rsilvers (Aug 23, 2015)

I think 3200 is a pleasant surprise. It could have been worse. It could have been 1800. Gemini Titan is claimed to be 4000, but may very well be 3200 since their 1500 lumen light was tested at 1200 - and that is over $100 more.

Kinda nuts for them to over-rate it though. If I succeeded in making a 3200 lumen light that was selling for $160 with a wireless remote and a quality 6x18650 hard-shell pack, I would think inflating the lumens would just scare away people who are willing to spend $160 on a light. I bet they would get more sales if they called it a 3200 "measured" lumen light.


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## rsilvers (Aug 23, 2015)

908 beam:


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## indebt (Nov 8, 2009)

rsilvers said:


> I think 3200 is a pleasant surprise. It could have been worse. It could have been 1800. Gemini Titan is claimed to be 4000, but may very well be 3200 since their 1500 lumen light was tested at 1200 - and that is over $100 more.
> 
> Kinda nuts for them to over-rate it though. If I succeeded in making a 3200 lumen light that was selling for $160 with a wireless remote and a quality 6x18650 hard-shell pack, I would think inflating the lumens would just scare away people who are willing to spend $160 on a light. I bet they would get more sales if they called it a 3200 "measured" lumen light.


 Yes for most of us here with some knowledge,,, overstated lumen claims or run times etc will erk many. I agree MS would attract more knowledgeable riders and IMO get more respect with honest claims.
Please keep in mind that the 1200 lumen Duo your referring to is last years model. I received an email from Chris Lie a while back. He was aware of our criticisms of their overstated lumen claims last year and responded with much confidence that claims would be actual in this years line up. The Xera has proved that,,, but seems MTBR has no other lights from Gemini in this years light shootout to confirm their outputs. My guess is the Titan will be much higher than 3200 lumens which is still plenty and I like the low profile of the lamp head better.


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## rsilvers (Aug 23, 2015)

Yes. The Titan looks good. I would be tempted to get one, but my iPhone mounts in the same spot.


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## MRMOLE (May 31, 2011)

rsilvers said:


> For anyone wondering, the actual light output of the MJ-906 is 3200 lumens according to test data referenced here:
> 
> Magicshine MJ-906 Headlight/Tail Light set with Wireless Remote Switch ? Action-LED-Lights
> 
> So it has 2.5x the output of the Gemini DUO and 1.5x as much battery capacity.


Nice surprise the 906 makes 3200 lumens but if you check out the beam pattern chart Jim also has on his site it will give you a lot more information about how the light will actually work. Center beam angle lux #'s are very low for a 3200 lumen light so you should expect a very bright/floody light with the 906. The Duo's center beam lux's are higher (more possible with optic change) so it will have better throw and make a better helmet light. My concern with the 906 is with that many lumens and the relatively short throw the close-up light intensity might be over powering and not really useful.









Second highest curve on the below chart is the 906.









Mole


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## rsilvers (Aug 23, 2015)

MRMOLE said:


> My concern with the 906 is with that many lumens and the relatively short throw the close-up light intensity might be over powering and not really useful.
> Mole


I of course have not tried one, but short throw should mean that the lumens are spread over a wider angle, which means it is less likely to be over-powering when used up close. If it had a lot of lux, then it would be over-powering up close. Low lux means less intense and less of a crazy bright hot spot. So it seems like it is a great bar light and just not a helmet light. And one can always turn it down and have longer runtime.


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## DustyTrail (Aug 21, 2015)

tigris99 said:


> I work nights......and ya dont get me started on the "cool blue" headlights either, OMFG. I stopped and cussed out a stupid teenager that thought it was cool to drive around town with them on high beams all the time. The worst of the ones with these new headlights that I want to bust out are the fraking pickup trucks, their damn headlights are right at my eye level or right in my mirrors.
> 
> HIgh powered headlights are good on open road without on coming traffic, especially here where there is deer like crazy. But ffs they need to come up with a way to mellow them out when on low beam.


Most high end newer model cars these days come standard (OEM) with 5k led's.

These typically have a lower cut off point for both the benefit of the driver and oncoming traffic.

My 2015 Mazda6 GT has a really low cutoff point and doesn't blind others at all.

Now on the other hand........there are those in lower end models who modify their own headlights and never bother to level them.


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## MRMOLE (May 31, 2011)

rsilvers said:


> So it seems like it is a great bar light and just not a helmet light. And one can always turn it down and have longer runtime.


I definitely agree the 906 will make a great bar light but from looking at the data from Action-Led-Lights site I'm guessing running it in one of the lower modes will give you better visual trail performance.
Mole


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## Cat-man-do (May 16, 2004)

MRMOLE said:


> I definitely agree the 906 will make a great bar light but from looking at the data from Action-Led-Lights site I'm guessing running it in one of the lower modes will give you better visual trail performance.
> Mole


Something about that graph doesn't make sense to me. If the 906 is an actual 3200 lumen the close in beam pattern would have to show more width than the Duo simply because of the sheer output but it doesn't. :skep: Anyone care to try to explain that?


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## MRMOLE (May 31, 2011)

Cat-man-do said:


> Something about that graph doesn't make sense to me. If the 906 is an actual 3200 lumen the close in beam pattern would have to show more width than the Duo simply because of the sheer output but it doesn't. :skep: Anyone care to try to explain that?


Your right, not what I expected to see for a 3200 lumen light. I'll have to contact Jim to see if he has an explanation but I'm guessing it may require rerunning the test which may not happen for a while considering it's Action's busiest time of the year. Thanks for pointing that out! I was totally focusing on the low throw #'s. Old eyes, small #'s, good excuse to buy a larger computer monitor.
Mole


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## Action LED Lights (Nov 11, 2011)

Cat-man-do said:


> Something about that graph doesn't make sense to me. If the 906 is an actual 3200 lumen the close in beam pattern would have to show more width than the Duo simply because of the sheer output but it doesn't. :skep: Anyone care to try to explain that?


I'll try and answer a lot of questions that have been put forth in this thread.
First, the 906 is indeed a wide flood. The tiny optics that are squeezed into it can only control a small amount of the light emitted by the led.

When looking at the graphs the 906 has a wider peak than the Duo. It takes a lot of lumens to make that wide peak. Think of the area of a circle as you increase the radius. twice the radius = 4 times the area so 4 times the lumens to light it.

I've been giving Magicshine a hard time for following their cheap competitors down the lumen's sell path. They have an integrating sphere so they know the real numbers. I talked them into revealing them to me and have them on the site.

One good thing Magicshine has added for the 900 series lights are higher capacity LG batteries. Their standard 4 cell is now 5200mAh. I also like the new slimline cases.

About the Duo output. We'll see what MTBR comes up with but I'm pretty sure it will be close to 1500 lumens. I know they have bumped it up from the previous version.


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## rsilvers (Aug 23, 2015)

Video of 906:


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## rsilvers (Aug 23, 2015)

Night ride:


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## tigris99 (Aug 26, 2012)

nice work on the video, sadly not impressed with the light though, only due to the rating its supposed to have vs what i see. IM curious to see the sphere results as im leaning more towards 2500-2800 lumens actual (based on video obviously) But looks like a very solid bar light.

Im am wondering why it looked like your light was pointed off to the side and not centered with your direction of travel? At first I thought it was like what i did and had the camera wrong but more I watched, the more I realized the light was pointed at a funny angle.


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## rsilvers (Aug 23, 2015)

Jim lists what he has reason to believe is the actual light output on his website. I am willing to test the current draw if that helps anything. I have a male cable stub but not a female one.

When it gets dark tonight I will do a beam shot on my bedroom ceiling compared to some other lights I have.

I had it on a curved part of the bar due to my iPhone being on the straight part of the bar.


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## rsilvers (Aug 23, 2015)

I forgot to mention in the video, that when the light is off, it is off. The instructions make no mention of unplugging it when not in use. I love that.


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## tigris99 (Aug 26, 2012)

Most instructions dont, not a good idea to store it plugged in, chances r you come to a dead battery. And Im not talking over night, couple of days wont hurt anything (just loose a few minutes run time). 

Also if it gets below the 50 deg mark, unless you store you bike inside your house (inside an attached garage doesn't count) where its kept warm, dont leave the battery attached either. Leaving lithium batteries store in the cold ruins them.


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## rsilvers (Aug 23, 2015)

My garage is heated to 50 degrees.

I don't plan to even keep the light on the bike so it won't stay plugged in .

Still any light that has illuminated LEDs when in the off position but plugged in is nonsense.


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## tigris99 (Aug 26, 2012)

Sounds odd but I actually prefer it. Reminds me I left the battery plugged in.


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## rsilvers (Aug 23, 2015)

I have the MS now for the bars, and ordered a DUO for the helmet.

I took the MS for a night-ride last night and think it is good. I even think it would be a good helmet light. 

I had the MS on the bars and a CygoLite 550 on the helmet. The 550 was tolerable but more lumens would have been better.


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## rsilvers (Aug 23, 2015)

I just fully charged the MS and put it on a fan, and have my iPhone pointed at an analog clock with time-lapse going. In about two hours I will know what the battery life is on max power at room temp.

Looks like I will have the DUO on Friday.


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## MRMOLE (May 31, 2011)

rsilvers said:


> I just fully charged the MS and put it on a fan, and have my iPhone pointed at an analog clock with time-lapse going. In about two hours I will know what the battery life is on max power at room temp.
> 
> Looks like I will have the DUO on Friday.


It looks like your going to answer the question I wanted to ask (actual runtime). "In about two hours", I thought MS claimed 3.6 hrs. on high for this light?
Mole


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## rsilvers (Aug 23, 2015)

My iPhone battery died. But the light was still going at 2 hours when I checked it. When I came back 10 minutes later, it was dead. 

So at least two hours and at most 2:10.


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## rsilvers (Aug 23, 2015)

They do claim 3.6 hours on 100% brightness.

I must say, I was prepared for the lumens to be much less than the claim, but for some reason I assumed the runtime was not over-stated.

Now I have to decide if I am going to give them a pass on both the overstated lumens (which I knew about) or the overstated runtime (which I did not). The amazing runtime was one of the main reasons that lead me to buy it.

I wish I had a tester to know if the battery is making its rated capacity.


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## rsilvers (Aug 23, 2015)

On the lowest brightness with a flashing tail-light at room temp and when cooled with a fan, the MS went 10.48 hours (10:29:00). 

They don't seem to make any claim except 11.3 for the longest, but that may be flashing mode.


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## rsilvers (Aug 23, 2015)

MJ-906 times so far:

4 power with tail-light on flash: ~2:00 
3 power with tail-light on flash: 2:39
2 power with tail-light on flash: 4:01
1 power with tail-light on flash: 10:29

#3 and #4 are barely any different visually. I would not be able to tell them apart if I didn't see it change from one to the other.


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## tigris99 (Aug 26, 2012)

Wait your running with a tail light, have you timed without the tail light running? Could be the run time they are coming up with.


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## rsilvers (Aug 23, 2015)

I am testing it with the tail-light on blink. The tail-light is maybe about 1/1000 the power consumption of the front light. Turning off the tail-light would probably add less than a minute to the run time.

It is only claimed to be 20 lumens, and it is a strobe so mostly not on. Probably the tail-light would run for a month non-stop by itself.

I ordered one of these to test the battery capacity:

1 5V 12V Battery Capacity Meter Discharge Tester 18650 Li ion Lithium Lead Acid | eBay

If the battery makes its rated capacity, I will probably give them a pass on the false runtime-claim because it is what it is, and I can turn the power down to 50% to extend run-time and still have 1600 or so lumens.

CygoLite 1300 Xtra claims 10 hours at 650 lumens and my MJ-906 made 10:29 with what seemed to be 600-800 lumens. So that seems ok.


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## nathan89 (Feb 7, 2015)

Why not just buy an IMAX B6 or something similar? Quite cheap on hobbyking


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## rsilvers (Aug 23, 2015)

That is a good idea. I have two hobby chargers already. The typical problem with them is that they require a power supply. Car batteries work, just annoying. But now that I think about it, I do have a Ham radio power supply that I got since I last tried to use the chargers.


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## tigris99 (Aug 26, 2012)

Dont need a power supply with any decent one, mine has a standard power supply cord that plugs in or can use a 12v power source.


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## Vancbiker (May 25, 2005)

rsilvers said:


> That is a good idea. I have two hobby chargers already. The typical problem with them is that they require a power supply.


Old laptop power supply from Goodwill or such makes a good unit to use with a hobby charger. Particularly the ones at 90 or more watt outputs.


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## rsilvers (Aug 23, 2015)

I finally found my hobby chargers - two DuraTrax ICE IntelliPeaks. And I have my new Ham radio power supply driving it. Wow - I paid $119 each for these a long time ago. Prices sure have come down. 

I am doing a 2-amp discharge to 2.8 volts per cell and will report the MJ-906 pack capacity soon.


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## rsilvers (Aug 23, 2015)

Battery is claimed to be 7800 mAh. It tested at 8045 mAh at 2 amp discharge. That is excellent and 3% better than claimed.

So the product is good. Marketing wise, they just need to change their claimed battery life from 3.6-13 hours to 2-10.5 hours and their lumens from 5000 to 3200.


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## tigris99 (Aug 26, 2012)

I feel you on chargers, my estation bc6 was $160 I think when I bought mine, what I find now is under $100 lol.


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## rsilvers (Aug 23, 2015)

Let's try to reverse-engineer their lumens...

At full power, I got two hours of runtime. That is 4 amps at 7.2 volts. 28.8 watts.

5×CREE XM-L2 and 5.76 watts into each one.

412 lumens each at 6 watts = 395 lumens each at 5.76 watts.

1977 lumens total. Assume 15% optics loss = 1680 lumens.

Hmm. Did I do that wrong? Seems low.


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## rsilvers (Aug 23, 2015)

DUO comes tomorrow. I will test that pack also. Shipped same day as ordered, but 2-day USPS priority is really 9 days. Government at work.


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## rsilvers (Aug 23, 2015)

I helmet mounted the DUO and walked around. It is nice.

Here is my comparison:

MJ-906 is $20 cheaper, has more than 2x the lumens, 1.47x the battery capacity, and has a nice tail-light that also works from the remote. Subjective quality of light-heads battery packs, and cables is equal to DUO. So the MJ-906 clearly gives you more for your money.

Cons: Needlessly misleads on runtime and lumens in marketing specs, but the actual specs are impressive. 

Doesn't include a helmet mount. 

Strobe is part of the normal mode cycle. Should be activated by turning light off, then holding down power button for 1 second.

Has four brightness levels but they are not spread out enough (they picked 25%, 50%, 75%, and 100% but should have picked 12.5%, 25%, 50%, and 100%.

Suggestion to the company: Change runtime claim to 2 hours on 100%, lumens claim to 3200, spread out the brightness more among the four modes, and make strobe activate as a hidden mode.

DUO has a smaller head and has a bit more throw (a bit more lux at the center of the beam), which is optimal for a helmet-light. It is nice in that you can pick the output for the three settings. It is also nice that it has three settings rather than four, and does not have strobe as part of the mode cycle. 

Also nice in that it looks a little more serious and comes with a helmet mount.
Cons: None.
Suggestion to the company: Include a GoPro mount.

Winner for bar light and general use: MJ-906.

Winner for value: MJ-906.

Winner for helmet light: Having both, the DUO is what I want on my helmet, but with the MJ-906, you get more light, more battery, and equal quality for less money. DUO has the modes and UI perfected with nothing annoying about it at all. So Toss up.

The MJ-906 makes a better helmet light than the DUO makes a bar light. It would take two DUOs on the bar to match one MJ-906.


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## rsilvers (Aug 23, 2015)

4-cell DUO pack made 5456 mAh. They claim 5200, so that is great that it is 4.9% better than claimed.

I will test the run times tomorrow.


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## rsilvers (Aug 23, 2015)

It is hard to pin down the run time of the DUO because it was toggling between two different brightness steps on its own thermal cycle, even though I had a high-powered micro fan right on it. It can never attain sustainable max brightness in the real world as it will always be too hot, even if it is cold out. The head is obviously too small for the heat it throws out to to sustain max brightness, and one should find a setting where it reaches equilibrium that will keep it from steeping down over time, so even if this light makes 1500 lumens for some brief period of time, it is not really a 1500 lumen light and it is pointless to keep it on 100% power unless maybe if it is below freezing out. Made for Canada I guess.

In my test, it went about 2:35 on the max "setting" (switching between two levels on its own) before it dropped to dim, and then went to over 5 hours total. This is a nice feature in that it won't just shut off on you, so you don't have to be as careful about being on too bright a setting as you would with the MJ-906.


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## rsilvers (Aug 23, 2015)

It is hard to know exactly since it ramps down over time, but it looks like just under 2 amps draw on max, or just under 15 watts. About 1/2 the MJ-906 in terms of draw and lumens. It is making me have doubts that the MJ-906 is really even 3200 lumens. It may be more like 2800 sustained. Lumen tests are done 30 seconds after turning on, and that is going to be more than over a two-hour period average.


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## indebt (Nov 8, 2009)

Vancbiker makes a heatsink gopro adapter for the Duo,,, that should solve the issues with the thermal.


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## MRMOLE (May 31, 2011)

rsilvers said:


> It is hard to pin down the run time of the DUO because it was toggling between two different brightness steps on its own thermal cycle, even though I had a high-powered micro fan right on it. It can never attain sustainable max brightness in the real world as it will always be too hot, even if it is cold out. The head is obviously too small for the heat it throws out to to sustain max brightness, and one should find a setting where it reaches equilibrium that will keep it from steeping down over time, so even if this light makes 1500 lumens for some brief period of time, it is not really a 1500 lumen light and it is pointless to keep it on 100% power unless maybe if it is below freezing out. Made for Canada I guess.
> 
> In my test, it went about 2:35 on the max "setting" (switching between two levels on its own) before it dropped to dim, and then went to over 5 hours total. This is a nice feature in that it won't just shut off on you, so you don't have to be as careful about being on too bright a setting as you would with the MJ-906.


Not sure what your "micro fan" is but googling that I saw nothing that IMO would provide adequate air volume to cool your Duo properly. I have an older Duo and agree that they tend to run on the hot side but running battery tests using a generic 10" house fan my light would stabilize at about 120° case temp in 80° ambient temp. (30° below the point of thermal step down). The current draw you stated in you next post is only about 10% higher than my older lamp which wouldn't raise the operating temp that much so your fan may be a problem. Does the light do this when your riding with it? My understanding is that all the Duo models have the same thermal protection characteristics which would mean it would step down to 20% power. When you say toggle between steps is this what it's doing (100% to 20%)? A Vancbiker finned GoPro mount would lower operating temps. 10-15° but if the problem is not just inadequate air flow (fan issue) my guess is there may be something wrong with the light.
Mole


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## rsilvers (Aug 23, 2015)

indebt said:


> Vancbiker makes a heatsink gopro adapter for the Duo,,, that should solve the issues with the thermal.


If it does solve the problem, that is great. Every bit helps, but I don't think it will be enough to really solve it.


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## rsilvers (Aug 23, 2015)

I don't know how much the light is stepping up and down. I have it on video but the camera adjusts to the light, so it is hard to know. My impression was that it was not stepping down very much.

Nothing is wrong with the light, other than the case cannot dissipate the heat properly, so it needs more surface area or it should be driven less - maybe back to the 1200 lumens it used to be. Realistically (using proper engineering standards) this probably is a sustainable 1200 lumen light at best. The MJ-906 head has deep heat sink fins.

Probably one should determine (using an IR thermometer) what power level will keep the head under 150 degrees at equilibrium, and then consider that 100% power. Anything above that should have been called a "turbo" mode or 110% or 120% power, etc.

I will use my Kestrel wind-speed meter to get a 5 MPH breeze going over the light head, and then figure out what the true sustainable max power setting is.

This is my fan:

AFB0424SHB Datasheet | DatasheetLib.com

AFB0424SHB

The 11,000 rpm one last on the list. I had it one inch away. CFM is only part of it as most of the air from a 10 inch fan will miss the light. My fan has 15.26 mm H20 pressure as the air is focused into a small area.

I will grab a heat sink off an old computer next time I come across one.


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## indebt (Nov 8, 2009)

rsilvers said:


> If it does solve the problem, that is great. Every bit helps, but I don't think it will be enough to really solve it.


 I use the typical 10" plastic fan outside so yes in cooler air approx. 40F when doing runtime tests on my 40 watt Betty's and never have any step down. My guess is either your fan isn't pushing enough air over the lamp head or maybe an issue with the lamp head. I read a post a while back probably on vancbiker heatsink thread where someone was using the Duo in Arizona 100F riding temp and wasn't having any step down issues with the light while using one of his heatsink mounts.

whether it's the Piko/Duo or any sub 60gram lamp head pumping out 1500 lumens,, anything shy of 10MPH IMO will cause the thermal to step in. That is where the X-2 got it right. A slightly beefier mass to handle the heat.


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## MRMOLE (May 31, 2011)

rsilvers said:


> I don't know how much the light is stepping up and down. I have it on video but the camera adjusts to the light, so it is hard to know. My impression was that it was not stepping down very much.
> 
> Nothing is wrong with the light, other than the case cannot dissipate the heat properly, so it needs more surface area or it should be driven less - maybe back to the 1200 lumens it used to be. Realistically (using proper engineering standards) this probably is a sustainable 1200 lumen light at best. The MJ-906 head has deep heat sink fins.
> 
> ...


This was just a suggestion but looking at the size of the fan (.5" wide) I would say the fan is inadequate. Best case with the fan that close you would have air flow on less than 50% of the light body. Use a bigger fan or at least move the micro fan a little further away and I'm pretty sure you'll get better results. I agree with your conclusion that the light-head body size is marginal to disapate the heat the light produces so getting airflow over as much of it at possible is absolutely necessary for this light. Still interested in whether it does this in actual use and if it toggles is between 100% and 20% power.
Mole


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## rsilvers (Aug 23, 2015)

MRMOLE said:


> This was just a suggestion but looking at the size of the fan (.5" wide) I would say the fan is inadequate.


The fan is 40mm wide (1.57 inches). It is exceptionally powerful - 24v and 11,000 rpm, and just look at the air pressure spec to see that putting it next to you is almost like using an air-compressor.


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## tigris99 (Aug 26, 2012)

That little fan will not come anywhere close to the air the case will get real world Cfm on a 40mm fan means little, does little to keep it cool because of its size.



I use 2 80mm and a 120mm high cfm fans with custom set up ducting to create proper full coverage air flow over a light head. Mimics real world conditions quite well where as your set up doesn't show any viable data because it only blows air on a very small portion of the total surface area.



The yinding is the same as a duo but probably lighter, less surface area. I can have it running at 1500 lumens out the front without step down in 70deg temps no problem as long as there is adequate air flow.



And I just read the data sheet. That fan is actually nothing special. 14.8m3 per minute at 11000 RPM.... Nothing more than a 24v video card chip cooling fan. Not enough to cool off a light head.


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## MRMOLE (May 31, 2011)

indebt said:


> . I read a post a while back probably on vancbiker heatsink thread where someone was using the Duo in Arizona 100F riding temp and wasn't having any step down issues with the light while using one of his heatsink mounts.
> QUOTE]
> 
> That would be me. As you said all these small approx. 1500 lumen lights tend to run hot. The X2 you used as an example is less effected by heat than the Duo but still dims in 100° ride temps but not very noticeable because the thermal protection lowers power gradually to maintainable level. Best of these lights I've tries is the BT21 w/Vancbiker mount. Produces best lux readings just below thermal step-down but has handled 107° ride temps with no thermal issues. Makes the most lux too (too bad receint quality issues and inconsistent delivery have become a problem with this light)!
> Mole


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## rsilvers (Aug 23, 2015)

tigris99 said:


> And I just read the data sheet. That fan is actually nothing special. 14.8m3 per minute at 11000 RPM.... Nothing more than a 24v video card chip cooling fan. Not enough to cool off a light head.


It's kinda special. I could not find such powerful fans anywhere, and only found one source to special order them. They keep my 3D print-head cool. It is more powerful than most 40mm fans (except for thicker ones).

A fan that is large (like the 10 inch example) just wastes CFM that misses the light. CFM is like lumens that is spread all over, and pressure is like Lux hitting the area that you want to illuminate.

They are generating an 11 mph wind on the light head, which is fair enough. On the twisty/rocky/rooty trails that we have here, we typically average 7 mph. Today's ride was wet, and I only averaged 5.2 mph (slipping on roots).

If the goal is to cool the head as much as possible, then I could use my 4,200 CFM carpet blower. But I would really like to stick to about 10 mph of airspeed. Besides, I have seen people post that these lights step down and overheat - so I don't know why anyone is surprised when it stepped down due to overheating.


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## MRMOLE (May 31, 2011)

rsilvers said:


> The fan is 40mm wide (1.57 inches). It is exceptionally powerful - 24v and 11,000 rpm, and just look at the air pressure spec to see that putting it next to you is almost like using an air-compressor.


Sorry for the typo. I'm not familiar with these fans but still think moving it further away from the light will help the air flow around the light better. Like I said, just a suggestion. Here's a pick. of the mount.









Mole


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## rsilvers (Aug 23, 2015)

Yes, it is a nice mount.

Here is mine:

GoPro mount for Gemini DUO bike light. by rsilvers - Thingiverse


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## rsilvers (Aug 23, 2015)

I will try it again now with a large house fan and set the distance to get 10 mph. I will take head-temp readings.


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## tigris99 (Aug 26, 2012)

Vance has lo-pro mounts as their called, it puts the tabs out back making the set up low profile, lower than the 3d printed one by a few mm. His aim there was just for what you wanted, keep them low. Heres mine with my yinding (duo clone) on my helmet.



For your fans: ya their powerful for their size, but they dont provide "real world" air flow over the light head. Their the same as high performance video card cpu fans. A regular household fan though the wind speed would be lower, will do a FAR better job of mimicing real use air flow. Its what Mole does IIRC. Its due to the SIZE of your fans. the blades are exceptionally small, designed to push air through a heat sink or controlled air flow enviroment. Thats why i had to create a ducting set up with my computer fans. because the center of the fans produces no air flow generating a "dead air space". So does little to actually cool the light head as the light is design to have flow over its entire surface area.

Create 10 mph air speed out of something bigger and you will get proper/better results. Heres my rig, 7mph wind speed:


Duo, like any light with thermal protection and especially SMALL LIGHTS, WILL STEP DOWN at low speeds, thats why they have thermal protection. You cant get high output in a tiny package without it. Not a fault of lighthead or anything else. Its the technology available. Emitters generate ALOT of heat at higher currents/higher output. Thats why you still see some dual emitter lights that are huge for being dual emitter. They deal with the heat much better but are big and heavy. Thermal management on the driver is what allows the smaller and light weight sizes. This is why we like the BT21, best case design and not much heavier than duo/x2/yinding.


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## rsilvers (Aug 23, 2015)

New setup:


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## tigris99 (Aug 26, 2012)

yeap, less wind speed but better flow, also should turn light head face into the air. Bet itll run longer without stepping down. as your fan is covering more area. Should get around 5 minutes or so with that set up before thermal engages.


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## rsilvers (Aug 23, 2015)

Test is running with light face into wind. Room temp is 68 F. 

After 17 minutes, wind is 6.5 mph and head temp is 144 F.


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## rsilvers (Aug 23, 2015)

I am not saying this design is bad. The concept of making it small and stepping down when there is no movement is a reasonable thing to do for a helmet light. I am mainly noting this as something to consider related to battery run time testing. If the batter lasts longer this time, we know it was cooled better because the emitters would be allowed to draw more current. 

Though maybe, as you said, the BT21 size is the best trade-off for dual emitters.


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## rsilvers (Aug 23, 2015)

Now I have to wonder... 

Is this 144F due to reaching that as equilibrium at full power, or has it stepped down to keep itself below 150F?

It would be nice if this was not stepped down and able to keep below 150 with the 6.5 mph wind.


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## rsilvers (Aug 23, 2015)

At 39 minutes it is 158 F.


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## tigris99 (Aug 26, 2012)

You would have seen the step down. This is equilibrium for the current temp/air speed. Like I said, proper air flow over the entire head makes a massive difference in cooling.

Edit: Seems its working as it should for low speed. 158 is right, itll do that till driver reaches step down temp. 150 is safety for the driver, case can reach higher, but step down doesn't occur till thermasistor on driver reaches preset temp.


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## MRMOLE (May 31, 2011)

rsilvers said:


> Now I have to wonder...
> 
> Is this 144F due to reaching that as equilibrium at full power, or has it stepped down to keep itself below 150F?
> 
> It would be nice if this was not stepped down and able to keep below 150 with the 6.5 mph wind.


Unless I've been misinformed when the light steps down from the thermal protection mode it should go to 20% power which would be easily detectable. If it looks slightly dimmer this would be normal as the emitters heat up. Still, 144° @ 68° ambient is a very hot running light (over 20° higher than my older duo runs). Not being able to run the light at 100% at anything over 70° without the risk of it dropping to 20% (I hate the preset) would be a major PITA IMO!!! Would require adjusting high modes programming to suit temperature and effectively having a lower powered light (I used to have mine set on 80% in the summer months before I got my Vancbiker mount). Considering your light has newer more efficient emitters and a slightly heaver light-head body for the small increase in battery draw it doesn't make sense that your getting that much rise in operating temp.
Mole


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## rsilvers (Aug 23, 2015)

I have not ridden with it. I have only been video recoding it in the fan. So I would not know if it stepped to 20% or not. 

By the way, the MJ-906 got up to 130F in the same test chamber. The heat sink on the back seems to work well.


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## rsilvers (Aug 23, 2015)

It makes sense because they may have turned up the current for 2016 to try to make a real 1500 lumens after getting slammed with the lumen claim in the MBTR review.


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## tigris99 (Aug 26, 2012)

The rear direct heat sink design is there the bt21 is superior, large fins basically mounted directly to the back of the emitter pcbs. Most efficient thermal dissipation design. But because of desire for all the options in drivers (all the user programmability) the mcu chip needed is rather large. For preset modes the mcu can go down to flashlight size, allowing much more available area to work with.

Lumen claims running short is common because many are rated at lumen output right at cold start. Every light for the first several seconds is brighter than it would be normally running.

The 20% step down is around 300 lumens, YOU WILL notice that visually being the 1500 lumen max. As you go higher output, it takes more lumens to be a visually noticeable change. But 20% lumen change is noticeable across any light. Even just sitting there looking at it.


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## MRMOLE (May 31, 2011)

rsilvers said:


> It makes sense because they may have turned up the current for 2016 to try to make a real 1500 lumens after getting slammed with the lumen claim in the MBTR review.


My reasoning is based on current draw (1.7 vs. just under 2 your measurement) minus light produced (1081 MTBR measured lumens vs. 1400-1500 est. lumens) should equal heat produced (losses from inefficiency). 15% more power going in and 30%+ more light going out should product less heat theoretically. This is just speculation since we don't have measured results on everything.
Mole


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## MRMOLE (May 31, 2011)

tigris99 said:


> The 20% step down is around 300 lumens, YOU WILL notice that visually being the 1500 lumen max. As you go higher output, it takes more lumens to be a visually noticeable change. But 20% lumen change is noticeable across any light. Even just sitting there looking at it.


That's not a 20% step down, it's a step down to 20% (impossible to miss). So approx. 1200 lumens!
Mole


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## rsilvers (Aug 23, 2015)

I don't consider my current draw estimate reliable as I didn't use a multimeter. 

Btw, the temp is 115 now for some reason at 2:15. To me that means the battery is getting low and it stepped down the current draw to lengthen runtime.


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## rsilvers (Aug 23, 2015)

At 2:30 it is down to 105F. Does that mean the output is not regulated to a constant brightness?


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## rsilvers (Aug 23, 2015)

2:40 down to 90 F.


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## rsilvers (Aug 23, 2015)

The MJ-906 stays bright and then dies, as I have come to expect from Surefire, Fenix, etc.

The DUO seems to get dimmer and dimmer over time, as if it were not regulated. Since it has programmable light levels, I would think it would be regulated. Does anyone know why it gets dimmer over time?

It was still running after 3 hours, but was pretty dim by then.

Since it was down to 115 F at 2:15, doesn't that mean that it already was below 3 volts per cell? If it was, and I am not sure that it was, wouldn't you call the runtime at max power to be below 2:15 rather than the 3 hours they list in the specs?



I just did a five mile ride. It never stepped down. 61 degrees and 100% humidity. Foggy and really I could not use a helmet-light in this much fog. So one needs a bar light. And one also needs a helmet light to look to the sides.


I really like the MJ-906 and DUO combination. I would not want a second DUO to replace the MJ-906 on the bars - I would need an Olympia to get more output and more of a flood to come close to replacing the MJ-906.


The DUO 4-cell pack worked well in my rear jersey pocket. No need to try to helmet-mount a 2-cell.


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## tigris99 (Aug 26, 2012)

You loose regulation when pack voltage input drops below emitter vF + driver requirement. Usually right at or just above 3v per cell. Which this is when you should be headed back before pack cuts off. In case of the duo figure each emitter needs 2.9v, so total 5.8 plus .25v for the driver. Below that point what voltage the emitters can get they pull the current based on that (direct drive). As voltage drops, less current is pulled, which is less lumens.

In the case of the 906, the emitters would be in parallel on an 8.4v pack. So it would never drop out of regulation due to voltage as vF for emitters is around 3v. And pack will cut off at no less than 5v. So never have that time of not being regulated. None of the type of light can step down voltage (buck driver) to start with then step up voltage when pack voltage gets too low.

Honestly except for rare occasion, its NOT good to run a pack down to the 2.5v cut off protection. 3v per cell (when duo looses regulation) is when you should recharge or as close to it as able.

The duo and any other half way decent lights all have "constant output" or constant current only until pack voltage drop below requirements. 906 running to cut off constantly is a good example of how to cut the lifespan of the pack by half or more. Also can force out of balance state, which more rapidly degrades the pack.


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## garrybunk (Feb 12, 2014)

Actually vF for an XM-L2 @ 2A is more like 3.3v. See testing here: Crash-testing a XM-L2 and a XP-G2 on copper Sinkpads | BudgetLightForum.com . The XM-L2 / XP-G2 / XP-L's are all tough to keep in regulation on a single cell (or dual emitters in series on 2 series cells) when driven at about 2A+. Of course quality of the cells play a part too. This is why I've chosen to run the LG MJ1's.

-Garry


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## tigris99 (Aug 26, 2012)

I was just using numbers for examples to explain it, I didn't look at exact vf specs. But xm-l2 vF is ~3.15 @ 2A

I found high voltage cells do little to change that, I guess there are some that capacity is rated above 2.5V. But really id rather have my ncr18650ga. Run time still gonna be more before dropping regulation.


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## garrybunk (Feb 12, 2014)

I thought you should have known better  .

-Garry


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## tigris99 (Aug 26, 2012)

I forget I better check specs with you around lol


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## rsilvers (Aug 23, 2015)




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## rsilvers (Aug 23, 2015)

DUO switched down to 20% today on a ride in 48 degree F temp. It was when I stopped. One just has to learn to put it into the lowest setting when you stop, which is pretty easy with the remote control.


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