Bicycle LED headlight

ddrueding

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On my ride this evening, on a particularly rough pothole, my headlight separated from my bike, flew through the air, and disintegrated on impact. I managed to tape the pieces back together for the ride home, but I do need a better light.

I would love to get one built by JTR; I have no doubt that the quality of his work is better than I can get commercially, and I'd rather pay my friends than someone I don't know.

Budget is $300-500
I'd like four brightness settings: Indicator (~100lm), 8 hours worth , 3 hours worth, and as much as 1200lm max.
If the 8 and 3 hour levels are between 300-600lm, that would be fine.

Does this sound reasonable? As I'm sure you all already understand, I don't really know what I'm talking about. ;)
 

timwhit

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The same thing happened to me a couple years ago, but it was the tail light. I bought it at Performance though, so I brought the pieces in and they gave me a new light.
 

Pradeep

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http://petzl.com/en/outdoor/headlamps/ultra-powerful/ultra-wide

One of these with the handlebar or cycle helmet mount? Nice thing is just quick detach and take it with you if you have to park the bike to avoid theft.

Downside: it isn't exactly light weight, but a 2000 mAh battery pack will tend to do that (there is an extended runtime 4000 mAh battery pack available as an option).

$430 via Amazon.
 

ddrueding

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http://petzl.com/en/outdoor/headlamps/ultra-powerful/ultra-wide

One of these with the handlebar or cycle helmet mount? Nice thing is just quick detach and take it with you if you have to park the bike to avoid theft.

Downside: it isn't exactly light weight, but a 2000 mAh battery pack will tend to do that (there is an extended runtime 4000 mAh battery pack available as an option).

$430 via Amazon.
http://www.pembaserves.com/2011/04/review-petzl-ultra-wide-headlamp/

Note the ultra wide gives 180 coverage versus the standard ultra which has a narrower beam.
That only looks like 300 lumens? And I don't need 180 degrees, even 90 is plenty. 60 with some falloff would be workable.
 

ddrueding

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For something capable of those speeds offroad I would look for a little more light than that. Also you don't need to worry about the lights having their own battery pack, right?
 

Pradeep

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It's just an 80cc machine for the kids that wouldn't exceed 20mph in the forested back paddock with defined trails. A 30 foot reach would be sufficient. For the motorbike I guess I could go for some Motolights.
 

ddrueding

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It's just an 80cc machine for the kids that wouldn't exceed 20mph in the forested back paddock with defined trails. A 30 foot reach would be sufficient. For the motorbike I guess I could go for some Motolights.
I'm not saying that some of their lights wouldn't work, just that you are paying a significant amount for a battery back as well that you wouldn't need (provided it has an alternator and a battery).
 

jtr1962

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Everything in the first post sounds reasonable. Give me some time to get back on specifics. I'm posting now from my A78NX which is marginally stable. I'll post in more detail when I'm on a machine which isn't in danger of randomly shutting down.
 

jtr1962

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Here's some pictures of the headlight I'm building. I still need to make the battery box and mounting bracket.




Regulator board (ZXLD1370-can be configured as boost, buck-boost, or buck):

 

jtr1962

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Getting to some specifics, the setup I have uses 6 XP-Gs with 10mm optics. In retrospect it would have made more sense to use XP-Es, even though the raw lumen numbers are less, because the smaller die would be focused into a tighter beam by the optics. Right now I have about 7300 candela and 1700 out-the-front lumens at full power (1000 mA). With XP-Es I may have had only about 1500 out the front lumens, but probably twice the candela. In practical terms that means a beam which throws further, with less sidespill.

I'm using four 26650 DeWalt cells for power. This gives 90 minutes on high. Again, in retrospect I would have used these instead. Same safe chemistry, but 3300 mAh instead of 2300 mAh. I just happened to have the DeWalt cells handy.

Getting to Dave's requirements, I can easily meet the lumen requirement with 5 XP-Es and 10 mm optics. 5 XP-Es would fit better on that heat sink, without overhanging. Four of the above cells would give about 2:15 run time, and proportionally more at lower outputs. At 100 lumens you can easily get 24+ hours runtime.
 

ddrueding

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Sounds good. What would the charger look like, just a wall-wart? I already have an outlet in my bike storage.

Of course, with the optics now missing on my 150+cd HL-EL135, I am in a bit of a hurry before I crash into something. What sort of timeframe can you manage?
 

jtr1962

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Sounds good. What would the charger look like, just a wall-wart? I already have an outlet in my bike storage.
Yeah, it would be something like that. I'm working out whether I can safely charge several of those cells in series at low current (i.e. overnight charge) without adding circuitry for cell balancing.

Of course, with the optics now missing on my 150+cd HL-EL135, I am in a bit of a hurry before I crash into something. What sort of timeframe can you manage?
I need to order emitters/optics from Cutter, which is probably 2 weeks to get to me. If that's too long, Mouser has Cree emitters. They don't give you a choice of tint or flux bins like Cutter does, but I can have them here within days. Same thing with the batteries. I have some spare optics on hand so we're covered there. In any case, once I figure out what I'm doing with regards to the battery compartment/charger/bracket on my light, I'll make one for your light to save time.

The good news here is most of the hard work is already done with regards to the design. The driver board works well. The charging circuit should be relatively simple if I can get away with not balancing the cells. It's basically just a constant current/constant voltage circuit. And the microcontroller programming for various levels should be easy (or I can do the 4 levels you want with a simple rotary switch which actually makes my life easier).
 

ddrueding

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Rotary would be fine. How big a deal is not being able to choose the bins? Will this be "water resistant"? I don't plan on riding in the rain, but it happens.
 

jtr1962

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Rotary would be fine. How big a deal is not being able to choose the bins? Will this be "water resistant"? I don't plan on riding in the rain, but it happens.
Regarding not choosing the tint bins, it shouldn't be that big a deal. Cree (actually all the LED manufacturers) are getting pretty good in that you don't get horribly green or purplish tints any more. As for flux bins, Mouser appears to be selling by flux. The downside is they only have the lowest flux XPEs (87.4 lm @ 350 mA) in stock. They have 122 lm XP-Gs, but like I said the XPEs will throw better for any given number of lumens.

Here's what I'll do since Mouser really has nothing worthwhile in XPEs, and I have some spare XPGs. I'll order the XPEs/optics from Cutter today. If they're not here by the time the rest of the light is ready I'll just use the XPGs I have on hand.

I can seal all the mating surfaces with a bead of clear silicon to provide some water resistance. It should be OK if you get caught in the rain, but don't expect the light to stay dry inside if you submerge it.
 

ddrueding

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Sounds good. Honestly I could wait if Cutter will provide a higher-performing unit. Just upgrade any shipping options and I'll cover it.
 

jtr1962

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I placed the order with Cutter. It usually takes 2 weeks give or take a few days. It'll probably take close to that long to finish up everything else anyhow. This place also had XP-Es, but mounted on a 20mm board. I would have had to dismount them from the 20mm board, and remount them on the 10mm boards I'm using (and hope they didn't get damaged in the process).
 

ddrueding

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Sounds good. Best to do it right than quickly I suppose, but this world of same-day shipping and overnight delivery has skewed the senses a bit.
 

ddrueding

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JTR,

How difficult would it be to incorporate a basic taillight into that battery pack? 5-10 surface mount red LEDs oriented in a 3" line on the narrowest board possible, with the smallest wire possible back to the battery pack? I'll just packing-tape/zip-tie it to my seatpost. No optics necessary.
 

jtr1962

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JTR,

How difficult would it be to incorporate a basic taillight into that battery pack? 5-10 surface mount red LEDs oriented in a 3" line on the narrowest board possible, with the smallest wire possible back to the battery pack? I'll just packing-tape/zip-tie it to my seatpost. No optics necessary.
Not hard at all. I've actually been running a similar setup on the Raleigh where I have a plug/wire to draw power from the headlight batteries for the taillight. It saves me the bother of messing with batteries for the taillight.
 

Howell

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Do you run the tail lights from the full voltage of the battery pack and waste heat or lumins or do you manage the uneven burn of the pack?
 

LunarMist

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Getting to some specifics, the setup I have uses 6 XP-Gs with 10mm optics. In retrospect it would have made more sense to use XP-Es, even though the raw lumen numbers are less, because the smaller die would be focused into a tighter beam by the optics. Right now I have about 7300 candela and 1700 out-the-front lumens at full power (1000 mA). With XP-Es I may have had only about 1500 out the front lumens, but probably twice the candela. In practical terms that means a beam which throws further, with less sidespill.

I'm using four 26650 DeWalt cells for power. This gives 90 minutes on high. Again, in retrospect I would have used these instead. Same safe chemistry, but 3300 mAh instead of 2300 mAh. I just happened to have the DeWalt cells handy.

Getting to Dave's requirements, I can easily meet the lumen requirement with 5 XP-Es and 10 mm optics. 5 XP-Es would fit better on that heat sink, without overhanging. Four of the above cells would give about 2:15 run time, and proportionally more at lower outputs. At 100 lumens you can easily get 24+ hours runtime.
Is there any redundancy in that setup? It looks they are all in the same circuit.
 

jtr1962

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Do you run the tail lights from the full voltage of the battery pack and waste heat or lumins or do you manage the uneven burn of the pack?
I would just put enough LEDs in series to come fairly close to the minimum operating voltage of the battery back (in this case about 10 volts so I would use 4 red LEDs in series), and then have a linear current regulator to absorb the remainder of the voltage difference. Another option is to use a switching regulator.
 

jtr1962

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Is there any redundancy in that setup? It looks they are all in the same circuit.
Yeah, they're all in series so if one goes open the string won't light. That's not really a concern though because LEDs almost never fail open circuit, and these aren't being overdriven. XP-Gs are speced for 1.5 amps. I'm only driving them at 1 amp tops. Most of the time it will be way less than that.
 

jtr1962

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I was pretty sick for much of the last few weeks, so things haven't progressed as rapidly as I thought they would. Don't forget also I'm basically designing this from scratch. If I was just copying an already built and proven design, it might have been done already.

Just to update you, I've been testing the batteries. It's pretty time consuming because I've had to run them through a bunch of cycles in order to determine capacity, and then pick four cells which are pretty close for the battery pack.

The parts from Cutter came a few days ago. Now it's just of matter of how long it takes to get everything together. I still haven't figured out what I'm doing with regards to the battery enclosure. I was thinking of making a box out of blank PCB stock.
 

ddrueding

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Didn't mean to rush you, just checking in. I just got my stitches out on Wednesday, so I haven't been riding (they were right down my spine).

If the enclosure is going to be a lot of work, you can skip that portion and I'll make it part of my eMachineShop project.
 

jtr1962

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Didn't mean to rush you, just checking in. I just got my stitches out on Wednesday, so I haven't been riding (they were right down my spine).
Ouch. :-o I'm going to hazard a guess that you either had an accident doing stuff around the house, or riding your bike.

If the enclosure is going to be a lot of work, you can skip that portion and I'll make it part of my eMachineShop project.
I'll let you know either way as soon as I make an attempt at it. A nice custom-machined enclosure would be nice. Heck, if we end up going that route, might as well incorporate the heatsink and mounting area for the LEDs into the same enclosure. Too bad I really have no experience in 3D design.
 

LunarMist

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I'm assuming it was not work related, but he does crazy stuff there, too.
 

ddrueding

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Thanks for the well wishes, it really wasn't a big deal. They just had to remove some stuff from my back and run some tests.

I have no practical experience in 3D design, but that usually doesn't stop me. ;) If you have the dimensions for the relevant bits, I'll start putting something together.
 

LunarMist

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Your back needs to last a long time and only gets worse with age. Stop abusing it now!
 
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