# Low-cost USB powered headlight



## Adventure-Biker (Feb 2, 2006)




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## Vancbiker (May 25, 2005)

USB power for a bike light is not efficient. You have an additional power conversion loss. Battery voltage to USB voltage requires voltage drop from 7.4V nominal to 5V. Then the light has to drop USB voltage to LED Vf so USB 5V to ~3.4Vf for the LED. Depending on the circuit design used the double conversion can easily lead to >30% energy loss. Even with the best conversion circuit designs energy loss will be ~10%


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## Adventure-Biker (Feb 2, 2006)

Vancbiker said:


> USB power for a bike light is not efficient. You have an additional power conversion loss. Battery voltage to USB voltage requires voltage drop from 7.4V nominal to 5V. Then the light has to drop USB voltage to LED Vf so USB 5V to ~3.4Vf for the LED. Depending on the circuit design used the double conversion can easily lead to >30% energy loss. Even with the best conversion circuit designs energy loss will be ~10%


Totally understand what you are saying here but most (if not all) other light systems don't even come close to this if you factor in cost & overall performance. I've had various lights through the years (some hi-end systems costing 12-15 times as much as this), and while they *might* have been nominally brighter, they didn't offer any advantage in burn time unless a big-ass battery was used, which could only be charged via mains AC power. Not an ideal solution for the many expedition style rides that I do.

All things considered, nothing comes close to these USB powered lights. I am able to run one for about 11hrs straight (low setting) on a 2 cell, 18650 Li-Ion power bank style battery that is about the size of a large Zippo lighter. It can also run off AA's if needed. Or a dyno hub. Or ANY USB power supply...

There simply isn't another light system that even comes close to the versatility, power, reliability, and ridiculously low cost... all in one package...as this one does.


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## Adventure-Biker (Feb 2, 2006)

Vancbiker said:


> USB power for a bike light is not efficient. You have an additional power conversion loss. Battery voltage to USB voltage requires voltage drop from 7.4V nominal to 5V. Then the light has to drop USB voltage to LED Vf so USB 5V to ~3.4Vf for the LED. Depending on the circuit design used the double conversion can easily lead to >30% energy loss. Even with the best conversion circuit designs energy loss will be ~10%


... oh, and I can also quick-charge 4 NiMh AA batteries in 10-15 minutes, drop them into a USB AA battery case, and have light for 3.5hrs (high), or 6-7hrs (low). You tell me what other light system is capable of this....


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## RAKC Ind (Jan 27, 2017)

Granted they work, its just a cheap flashlight in an 808 clone housing.

Most lights will have the same or more runtime in low mode

But the ease of changing batteries and using power banks isnt all bad but you can see for trail use there is a dual set up running. So convenience of USB is lost, especially when much smaller, light form factor is available with the same/more lumens as both combined.

Cool that you made something like that work and works for you. For what you do there is some benefits. Just stuff that cheap is worse than gambling at a casino when it comes to reliability and performance. 

Sent from my SM-G950U using Tapatalk


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## Vancbiker (May 25, 2005)

Adventure-Biker said:


> ... oh, and I can also quick-charge 4 NiMh AA batteries in 10-15 minutes, drop them into a USB AA battery case, and have light for 3.5hrs (high), or 6-7hrs (low). You tell me what other light system is capable of this....


If that light can run on 4AA NIMH cells for 3.5 hours that's less than 700mA (excluding driver losses) to the LED. An XML T6 LED at 700mA is less than 300 lumen. Thing is a candle compared to real mountain bike likes if that's the case. Lots of lights out there can run at <300 lumen for 3+ hours.

Lots of cheap POS Chinese lights out there. This is just another one of many.


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## Adventure-Biker (Feb 2, 2006)

Vancbiker said:


> If that light can run on 4AA NIMH cells for 3.5 hours that's less than 700mA (excluding driver losses) to the LED. An XML T6 LED at 700mA is less than 300 lumen. Thing is a candle compared to real mountain bike likes if that's the case. Lots of lights out there can run at <300 lumen for 3+ hours.
> 
> Lots of cheap POS Chinese lights out there. This is just another one of many.


I don't know the actual lumen output of this light. I have no way to measure that. They are advertised at anywhere from 1000 to 1200 lumens and of course the actual output is nowhere close to that. And the XML T6 LED is what the advertising says. Who knows if it is a different kind of chip.

What I CAN tell you is that it's definitely way more than 300 lumens, and a far cry from the candle you mentioned. I'd say 700-800 is about right. I have put these lights side by side against many mid to high end name brand lights and these USB lights are just as bright. In some cases a little less but not by much. If you don't believe it then you should try one for yourself and you'll be pleasantly surprised.


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## Adventure-Biker (Feb 2, 2006)

RAKC Ind said:


> Granted they work, its just a cheap flashlight in an 808 clone housing.
> 
> Most lights will have the same or more runtime in low mode
> 
> ...


How so? There are so many compact power bank style batteries available with dual USB outputs... just look at some of those from Anker for example. Just for shits & giggles, I have run 2 of these USB lights together on the high setting off a single 10,000mah battery for over 6 hours straight. The battery was no bigger than 2 Powerbar energy bars stacked on top of each other. And that was way overkill in terms of brightness etc.

As for reliability, I thought exactly the same thing when I first purchased one of these. Which is why I bought 2. I have now been using this light for nearly 3 years...2-4 times per week, 2-3 hours on average per ride. I've also done many overnight rides & races with it as well as a number of multi-day expedition type rides and the light works just as well as the day I bought it. So I'd say it's pretty darn reliable.


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## RAKC Ind (Jan 27, 2017)

Adventure-Biker said:


> How so? There are so many compact power bank style batteries available with dual USB outputs... just look at some of those from Anker for example. Just for shits & giggles, I have run 2 of these USB lights together on the high setting off a single 10,000mah battery for over 6 hours straight. The battery was no bigger than 2 Powerbar energy bars stacked on top of each other. And that was way overkill in terms of brightness etc.
> 
> As for reliability, I thought exactly the same thing when I first purchased one of these. Which is why I bought 2. I have now been using this light for nearly 3 years...2-4 times per week, 2-3 hours on average per ride. I've also done many overnight rides & races with it as well as a number of multi-day expedition type rides and the light works just as well as the day I bought it. So I'd say it's pretty darn reliable.


3 yrs ago, likely a "new" product at the time so they were ok. We see that a lot with cheap lights. Originals are decent enough then quality goes to crap within 6 months.

It works for you but between your 2 lights combined you get what, 1000 lumens at best. Good enough for your use (luckily cool white lights which helps). Just saying they are lacking in a lot of areas (like most powerbanks arent water proof) including output and such for most others.

But what youve done is what the spirit is a lot around here, take something cheap and make it work for what you need. Kudos for that.

Sent from my SM-G950U using Tapatalk


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## Adventure-Biker (Feb 2, 2006)

RAKC Ind said:


> 3 yrs ago, likely a "new" product at the time so they were ok. We see that a lot with cheap lights. Originals are decent enough then quality goes to crap within 6 months.
> 
> It works for you but between your 2 lights combined you get what, 1000 lumens at best. Good enough for your use (luckily cool white lights which helps). Just saying they are lacking in a lot of areas (like most powerbanks arent water proof) including output and such for most others.
> 
> ...


Again, I don't know the actual lumen output because I have no way to measure that. What I can say is that 2 of these lights running together side by side is overkill... way more light than what is actually needed in any riding condition. I've ridden with 1000 lumen lights in the past and this setup is way brighter than that. While it is true that most powerbanks etc aren't waterproof out of the box there are steps that can be taken to indeed make them (and most any electronic device) waterproof, or at least highly water resistant. I've used this setup on multi-day rides where it rained for 48 hours nonstop and never had a problem.

Of course I can see by your username (RAKC Ind) that you are a principal in a bike light company so of course It only makes sense for you to poo-poo on anything else, whether it be factual or not. I'd actually find it odd if you didn't. Just sayin'...


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## alexbn921 (Mar 31, 2009)

For a low cost solution it's not horrible. I would always carry at least 2 of these as 1 can fail and leave you stuck in the woods.
Beam pattern is awful. Even with the wide beam setup the light is way too concentrated.
Output is hard to tell but I suspect it's in the 250-300 range on high.
It's light and you can afford it. It's not a good or reliable light though.


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## RAKC Ind (Jan 27, 2017)

Adventure-Biker said:


> Again, I don't know the actual lumen output because I have no way to measure that. What I can say is that 2 of these lights running together side by side is overkill... way more light than what is actually needed in any riding condition. I've ridden with 1000 lumen lights in the past and this setup is way brighter than that. While it is true that most powerbanks etc aren't waterproof out of the box there are steps that can be taken to indeed make them (and most any electronic device) waterproof, or at least highly water resistant. I've used this setup on multi-day rides where it rained for 48 hours nonstop and never had a problem.
> 
> Of course I can see by your username (RAKC Ind) that you are a principal in a bike light company so of course It only makes sense for you to poo-poo on anything else, whether it be factual or not. I'd actually find it odd if you didn't. Just sayin'...


Not sure why your getting defensive over making the point that lights this cheap are a lottery and this time you won which is rare.

Ive been modifying lights, custom making my own, etc for some time. Have a sphere and other test equipment, reflow LEDs, modify drivers, etc all just for fun. Long before I had a "stake" in anything. And never am I "everything else is poop". Theres a lot of great lights out there, we just lost an AWESOME US brand last month (sad, those lights being made by 1 man was awesome, we still have Amoeba which are cool, tiny ass lights). But $10 lights being great is a 1 time thing honestly.

Sent from my SM-G950U using Tapatalk


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## Vancbiker (May 25, 2005)

Adventure-Biker said:


> .....What I CAN tell you is that it's definitely way more than 300 lumens,


What you are not getting is that there is no way it can run over 3 hours on 4 AA NIMH cells as you stated earlier if it does output more than ~300 lumen on high setting. It is just not possible as the battery pack does not have enough capacity for that. It's pretty simple math and data from Cree. It the LEDs are not Cree, then there will be even lower output as the common XML clone LEDs are not as bright as Cree LEDs.

You're trying to blow smoke up a group of folks that know quite a lot about lights and the technology behind them. If you make wild claims about performance, you're gonna get called out.


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## ledoman (Apr 17, 2012)

If Adventure-Biker would make good sharp macro picture of the led we can identify it for shure or at least telling is it Cree or not.

Next, using cheap USB volt and ammeter would tell the current to the light. Then we would know enough.

As said the others I don't expect much power to be used, too. Of course eyes can adapt and things might look bright. Well, not for all of us, but might be good starting point. Still, I would use two completly independent sets, just in case. Over the years I've seen many lights and most can survive, some time at least. Most problems were with cheapo batteries. So if not running hard even cheapo things can work. There is bunch of things which makes a light the LIGHT.


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## Adventure-Biker (Feb 2, 2006)

Vancbiker said:


> What you are not getting is that there is no way it can run over 3 hours on 4 AA NIMH cells as you stated earlier if it does output more than ~300 lumen on high setting. It is just not possible as the battery pack does not have enough capacity for that. It's pretty simple math and data from Cree. It the LEDs are not Cree, then there will be even lower output as the common XML clone LEDs are not as bright as Cree LEDs.
> 
> You're trying to blow smoke up a group of folks that know quite a lot about lights and the technology behind them. If you make wild claims about performance, you're gonna get called out.


Not blowing any smoke or making any wild claims here at all here, man. Without getting into any math here (I don't know the real-world specs on this light), but what I can tell you with utmost certainty is that this light will indeed run 3 hours straight on 4 2400mah NiMh AA cells. I've done it time and time again. In fact, that's one of the best things about this light because I can quick-charge those same 4 AA NiMh cells in under 15 minutes (usually more like 10-11 minutes), and get 3hrs of burn time on high, more than double that on low). Don't beleive me? Try it then!


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## Adventure-Biker (Feb 2, 2006)

alexbn921 said:


> For a low cost solution it's not horrible. I would always carry at least 2 of these as 1 can fail and leave you stuck in the woods.
> Beam pattern is awful. Even with the wide beam setup the light is way too concentrated.
> Output is hard to tell but I suspect it's in the 250-300 range on high.
> It's light and you can afford it. It's not a good or reliable light though.


Not sure which light you've used but I've used 300 lumen lights before and they are like a candle compared to this one. And as for reliability, I've been running one of these hard for nearly 3 years and it has never let me down. I've done numerous all-night rides where I've literally run the light for 10-11 hours continuously and have never had a problem. If I had to ride across Antarctica next week I wouldn't think twice about using this light.


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## Adventure-Biker (Feb 2, 2006)

ledoman said:


> If Adventure-Biker would make good sharp macro picture of the led we can identify it for shure or at least telling is it Cree or not.
> 
> Next, using cheap USB volt and ammeter would tell the current to the light. Then we would know enough.
> 
> As said the others I don't expect much power to be used, too. Of course eyes can adapt and things might look bright. Well, not for all of us, but might be good starting point. Still, I would use two completly independent sets, just in case. Over the years I've seen many lights and most can survive, some time at least. Most problems were with cheapo batteries. So if not running hard even cheapo things can work. There is bunch of things which makes a light the LIGHT.


If you watch the video you will see partway through that I did indeed test this light using a USB volt/ammeter. It uses about 1.5A @5V on high and averages about 500-700mA on low (the current consumption on high is pretty steady but it fluctuates on low).

I can't understand why people are downplaying the brightness of this light when they haven't tried or used one themselves. I regularly do night rides on tech. singletrack with other riders who have all sorts of other various lights and this USB light with the wide angle lens doesn't give up anything to what they're running.

These are some closeups of the LED element with the front lens and reflector removed:


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## Vancbiker (May 25, 2005)

Adventure-Biker said:


> .....Without getting into any math here......


I don't doubt you that it can run on high for 3 hours on a set of 4 AA NIMH cells. It is just going to be outputting ~300 lumen max to do it.

If one gets into the math....

4 AA NIMH cells in a series pack will make nominal 4.8V and 2100mAh. That's 10Wh (VxA). So for 3 hours you have 3.3W per hour you can use from the battery. An XML T6 running at~1000mA is using 3W because it takes ~3V to drive it at 1000mA current. An XML T6 at 1000mA puts out a bit over 300 lumen per the XML datasheet....

http://www.cree.com/led-components/media/documents/XLampXML-11E.pdf

The above numbers are neglecting driver and optic losses. Driver will only be 90% efficient at best and optic losses of >10% are typical of LED lights.

I get that you like this light and all, but it, like most cheap china lights does not output anything near the manufacturers advertising numbers.


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## alexbn921 (Mar 31, 2009)

I always ride with 2, sometimes 3 lights on my night rides. Having 2 primary and 1 little light you can look at things in your hands is nice.
Some Cree t6 math
Cree T6 LED's put out 310 Lumens-per-Watt XM-L emitters running at 700mA. Their efficiency drops off the more power you put into them.
You have 2400/700mA = 3.42857 hours run time with a 100% efficient converter.
2.5-3 hours at 310 lumens output seems reasonable.
Running at 620 lumens you would be getting sub 1 hour run times factoring in all of the losses.
With your big battery running 1.2-1.4 amps you will get around 500-590 lumens with a 2.5-3 hour run time.

Beam pattern is a huge factor in how usable the light is. A narrow spot will feel brighter and project further but will blind your peripheral vision.
What is the total cash outlay for this project?
$10 for the led.
$4 diffuser lense.
$10 for the batteries
$15 charger 40 for quick charger
$7 for usb pack.
so around $46 for a complete setup which will get you a similar output name brand self contended light

It takes longer than 10 minutes to fast charge dead batteries too. 20-30 minutes is more realistic.

Something like this light would be a much better long term investment.
https://www.amazon.com/NiteRider-Lu...UTF8&qid=1508281359&sr=1-5&keywords=niterider


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## ledoman (Apr 17, 2012)

Adventure-Biker said:


> If you watch the video you will see partway through that I did indeed test this light using a USB volt/ammeter. It uses about 1.5A @5V on high and averages about 500-700mA on low (the current consumption on high is pretty steady but it fluctuates on low).
> 
> I can't understand why people are downplaying the brightness of this light when they haven't tried or used one themselves. I regularly do night rides on tech. singletrack with other riders who have all sorts of other various lights and this USB light with the wide angle lens doesn't give up anything to what they're running.
> 
> ...


Hmm, watched your video at 2:07 and at 3:25 I've seen light with different led than this on your pictures. On video I would say it's probably Lattice Bright counterfeit of Cree XM-L (hard to say for shure) while on your picture is very likely geniue Cree XM-L2. For the price I doubt you would still get geniue Cree leds nowadays when so many fakes are out there. Of course anything is possible.
Shurely your pictures of leds doesn't match the first post and video title stating leds are XM-L.

In video Voltmeter indeed shows light is pulling 7W at the start on hi mode which is pretty good. Would be interesting to know if that power is mainatined for longer time or it is just in the first few seconds.

Edit: added calculation 
If we take 7W of input then with average driver efficiency of 85% leds gets 6W to the led, not counting looses on wires and USB connector. USB wires are tipicaly thin and we can only gues which AWG is used. Very likely AWG 24 or AWG 22 at best. So I would say leds gets about 5W. This is somewhere around 1600mA current at Tj = 25°C ie. when the light is cold. At Tj 75 °C you loose 10% flux according to Cree datasheet. Using Cree tools you can find XM-L T6 can produce 516 Lm at that heat point. Now taking looses from reflector and front glass you would get 400 - 450lm of output, at best.

In fact you were right, there is 700-800 lm, just forgot to tell it's from two lights  Anyway it's the concentrated beam from SMO reflector which gives you feeling the light is very bright and lumens does not tell a bit about this.

I'm out....


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## alexbn921 (Mar 31, 2009)

Adventure-Biker, what are you trying to accomplish with your post? It's a light and you like it, that's all that really matters.


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## garrybunk (Feb 12, 2014)

Nothing to see here folks . . . move along.

-Garry


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## Adventure-Biker (Feb 2, 2006)

ledoman said:


> Hmm, watched your video at 2:07 and at 3:25 I've seen light with different led than this on your pictures. On video I would say it's probably Lattice Bright counterfeit of Cree XM-L (hard to say for shure) while on your picture is very likely geniue Cree XM-L2. For the price I doubt you would still get geniue Cree leds nowadays when so many fakes are out there. Of course anything is possible.
> Shurely your pictures of leds doesn't match the first post and video title stating leds are XM-L.
> 
> In video Voltmeter indeed shows light is pulling 7W at the start on hi mode which is pretty good. Would be interesting to know if that power is mainatined for longer time or it is just in the first few seconds.
> ...


The LED in these photos is the same exact unit in the video, and also the same exact unit that appears on my bike on other videos on my YouTube channel. I've been using this same unit for nearly 3 years now. Not sure why you'd say it is a different unit. I initially purchased 2 of these from the same seller because I too, was really skeptical about the performance and reliability at first. One of the first things I noticed was that the beam pattern was indeed narrow and concentrated, which is why I added the wide angle lens. The light is bright enough that there is no perceptible loss in brightness or intensity with the wide angle lens. Brightness, coverage, and beam pattern are fantastic. The light has been so good that the second one I purchased has just been sitting in a box the entire time basically unused. As for the lumen output, I the 7-800 lumens was my estimation when compared right alongside other lights that have a known output in this range. I never stated that I knew exactly what the output of the USB light was. I have run the light with the volt/ammeter hooked up for several minutes but haven't run it like this for an extended period. What I can tell you is that it maintains its brightness for a full charge cycle on a Li-Ion battery pack right to the point to where the battery reaches it's cutoff voltage, at which point the light cut's of completely. I've run it on a 2 cell, 5200mah pack for 3:30-3:45 on high and on low I've gotten a hair over 11hrs. I've also run it on a 10,000mah pack and gotten over 6hrs on high. I've also run both lights on high off a single 10,000mah pack with dual USB outputs for 3:30 at which point I ended the ride (the battery still had power to spare). I don't have a way to measure the output but running 2 of these lights has got to be way more then the 800lm you mention. I only did that to try it out but it's overkill, as one has more than sufficient output.


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## Vancbiker (May 25, 2005)

It's a miracle light. Defies current state of the art battery capacities and lumen/watt output. Cree should buy it back so they can figure out the miracle emitter and Panasonic should look at the battery to learn how to make a more powerful cell. You are so lucky to have found these!


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## BigHit-Maniac (Apr 13, 2004)

AAAAnnnnnnnnddddd.... I'll stick to my NiteRider Lighting. That looks like a gas station light that goes on a key fob. 

I can guarantee you that thing aint "1200-1300" Lumens either. 

My little brothers NiteRider Pro 750 light on a 2-cell L-ion battery is significantly brighter than that.


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

I took a look at the video and the guy does a decent job at reviewing the lamp. No telling the actual output on high but if the LED is getting near 1800 milliamps it should be somewhere around 500-600 lumen. I believe him when he says he gets over 3hrs out of his two cell Li-ion battery. However I can't see the lamp getting more than 2hrs using the 4 x AA cell holder if used on high. That said a typical 4 x AA holder isn't going to provide 2A of output current. If it does it isn't going to last long on standard alkaline's. 

What I like about this type of light is that it offers the person on tour the option of buying AA cells while on the road assuming they have no access to electricity. 

All things considered it's an interesting concept to use a USB connector


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