Electronics, Lighting, & Gadgets - Q's for DIY light people

I have come to the realization that a light system that meets my needs would be too expensive for me to buy at this point, and building a headlight can't be any harder/more frustrating than building wheels right? So, I need some advice, well lot's of advice.

Basically, I want to build a headlight that can get a minimum of 8 hours to a charge and bright enough for fast, poorly lit descents on back roads. I'd like to do a 300 km brevet this spring, possibly a 400k so I need a minimum of a full night's charge, and it needs to be fairly rainproof.

A schmidt hub dynamo would be ideal but is out of my price range. Most battery light systems seem oriented towards mountain biking or commuting and lack the time requirement.

I'd like to spend less than $80 and know how to solder, and have a basic knowledge of how current and wiring works. Any good advice is extremely welcome.

Also, Happy New Year.

I built lights from two of these, 3-18V CREE LEDs:
http://www.dealextreme.com/productimages/sku_6090_1_small.jpg
http://www.dealextreme.com/details.dx/sku.6090
I run them from a 14.4v lithium 4800 maH battery. They draw about 250 mA each, so get about 9 hours with both on or 18 hours with only one in use. One is enough if I'm not going too fast, and two will let me ride at a brisk pace. I have mine mounted on my forks; homemade, but plenty bright and long run time and cheap. I can also run them off AA or AAA batteries if I carry a battery holder with me (4xAA), since these lights can run off any input from about 3 to 18 volts DC.bikeforums.net/showthread.php?t=373642"]http://www.bikeforums.net/showthread.php?t=373642[/URL]
Total investment was about $70 for the Li-ion battery and charger, plus $20 for the CREE lamps. I had all the wiring, tubes, and connectors lying around.

I have come to the realization that a light system that meets my needs would be too expensive for me to buy at this point, and building a headlight can't be any harder/more frustrating than building wheels right? So, I need some advice, well lot's of advice.

Basically, I want to build a headlight that can get a minimum of 8 hours to a charge and bright enough for fast, poorly lit descents on back roads. I'd like to do a 300 km brevet this spring, possibly a 400k so I need a minimum of a full night's charge, and it needs to be fairly rainproof.

A schmidt hub dynamo would be ideal but is out of my price range. Most battery light systems seem oriented towards mountain biking or commuting and lack the time requirement.

I'd like to spend less than $80 and know how to solder, and have a basic knowledge of how current and wiring works. Any good advice is extremely welcome.

Also, Happy New Year.

I think your budget is unrealistically low, unless you count lugging huge amounts of batteries as not a problem. Especially given the brightness/runtime/proofness you mention.

8 hr. runtime is kinda the killer. For your described descents, I wouldn't want less than 20 watts of halogen, the least expensive bright light option. That would require either a big heavy sla, about 96 AA nimh cells, or an expensive li-ion pack. Do you really need 8 hrs? Most double centuries I've seen only have a couple of hours of dark riding.

wow 8 hours, if i used both my 12v 7ah batterys I could probaly get that on a 20 watt bulb, but 10lbs extra weight plus the batteries for you would be $20 each plus shpping, what about those fenix lights everyone likes so much??

for under 80 bucks you can get the following
$8 / 20 watt pond light harbor freight http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=47604
$50 2 batteries from battery space 12v 7.5ah http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=2147
$10 misc wiring and connectors, conduit clamp to attach to handle bar.
$5 trickle charge harbor freight on sale this week http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=42292
total $72 plus you still need a trunk to carry the batteries, I have this trunk http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=2147

need more help please ask me.

I'm not sure how bright you need for this project. I was checking possible LED options, and if 140 lumens is enough (manufacturer's claim, some have claimed that the number is slightly exaggerated), then you might want to consider mounting a 2D Maglite with a 140 lumen 3W Terralux upgrade module to it. Note: this is NOT the Maglite standard 3W LED. Fill it with two 10000 mAh NiMH cells (found online, NOT the ones you'd find at a grocery store). The Maglite is 10 inches long, so it might be a tad bulky, but then the light should just run for 8 hours. In terms of charging, see if someone has a D cell smart charger handy (I hear these are expensive). If not, you can charge them using a dumb charger+timer, or rig something to hook it to an AA smart charger that's based on voltage drop detection.

There seem to be a bunch of Maglites on sale for <$20 these days. The LED is around $30. IIRC, someone sells mounts that would let you mount the light onto the bike. Alternatively, I remember somebody figured out a way to mount only the lighthead, and power the thing with a water bottle battery or something like that.

Disclaimer: I do not have personal experience with riding with a Maglite. Nor do I have personal experience with the LED mod; I'm going by what I've read and so on. If you go with this, I'd strongly recommend doing a dry run before the actual trip just to make sure there are no surprises.

You can probably make a nice LED system for 200$.
Power:
You'll need either 25AAs + charger (80-100) or a hub dyno; shimano 3n71 is around 90$ and almost as good as the schmidt. Build yourself around existing wheel.

Get a triple cree MR11 LED and optic from cutter, around 50$

Build one of Martins 5w circuits for 10-20$... this will drive the LEDs at around 20w halogen equivalent.
http://www.pilom.com/BicycleElectronics/DynamoCircuits.htm

Scrounge parts for DIY housing. Free.

Add a cateye EL530, redundant light with 8hrs runtime, 40$. Upgrade the LED to latest SSC U bin(twice as bright) for 8$.

If you can really only stretch to around 80$, go with 2 cateye el530s, upgraded. People do brevets on a lot less.

You can probably make a nice LED system for 200$.
Power:
You'll need either 25AAs + charger (80-100) or a hub dyno; shimano 3n71 is around 90$ and almost as good as the schmidt. Build yourself around existing wheel.

Get a triple cree MR11 LED and optic from cutter, around 50$

Build one of Martins 5w circuits for 10-20$... this will drive the LEDs at around 20w halogen equivalent.
http://www.pilom.com/BicycleElectronics/DynamoCircuits.htm

Scrounge parts for DIY housing. Free.


I'd really like to stay away from a hub dynamo, and according to a Bicycle Quarterly test, the 3n71 is has slightly lower efficiency than the cheaper, previous version.



Add a cateye EL530, redundant light with 8hrs runtime, 40$. Upgrade the LED to latest SSC U bin(twice as bright) for 8$.

If you can really only stretch to around 80$, go with 2 cateye el530s, upgraded. People do brevets on a lot less.

You can upgrade the LED on the EL530? I already have one of these lights and while it's ok for lit roads, if I could add a second and upgrade the LED's that might be my best option. Where can I get the correct LEDs?


Thanks everyone else for the suggestions, but I think using my current EL-530 with a second and modifying their LEDs is the best option.

I used a 2-AA LED 3-watt mag lite on my road bike and it worked fine. Small, light weight, and 2.5 hour run time with just 2 AA disposable Alkaline batteries. I did an all night run once with it and it worked out fine. Check-in and rest stops were about 2 hours apart so I would always put in fresh batteries at every stop. I later modified the light to run with a bottle type dynamo. I used 2 junk Ni-CAD batteries externally mounted between the light and the bridge rectifier used with the dynamo to convert AC to DC. The batteries had very little capacity left in them and would only power the flashlight for about 15 minutes. Normally I would have thrown them in a battery recycling box at Radio Shack. I used them as voltage and current regulators for the mag lite flashlight. The batteries load the dynamo when output voltage approaches the rated voltage of the batteries. This prevents voltage from exceeding about 3 volts. The batteries also absorb excess current not used by the light. As the batteries were worn out junk overcharging them was not a problem. There efficiency was so poor past there intended usefulness the excess current simply vanished in the form of heat. You could fill them getting a little warm but nothing to be worried about. The batteries also kept the flashlight illuminated for about 15 minutes at stops. I cut a fiberglass tent pole to use as a replacement for the batteries in the flashlight. It already had a hole in the center so a wire could be easily pushed through and soldered to a modified wire terminal for the positive battery contact. The other end had another wire terminal soldered to the ground wire with a second terminal acting as a washer so the spring in the battery cap would not bind up as you screw in down. I had to drill a small hole in the middle of the cap to pass the wire through. Here is a photo of the modified light.
http://i143.photobucket.com/albums/r154/n4zou/batteryadaptor.jpg
It would be very easy to attach the light to a 2 D battery holder. 2 D batteries would easily power the Mag light all night.
Here is a photo of it mounted on the handlebar of my touring bike.
http://i143.photobucket.com/albums/r154/n4zou/Hpim0305.jpg
I used this lighting setup until I built a new headlight using a Luxeon 1-watt LED, matching Fraen elliptical optics, all mounted in a 1” PVC pipe coupling.
http://www.luxeonstar.com/
http://i143.photobucket.com/albums/r154/n4zou/Hpim0312.jpg
The reason for the upgrade was the ability to power and recharge a Palm TIX and GPS receiver while on tour. Here is the circuit I use.
http://i143.photobucket.com/albums/r154/n4zou/all-standlightUSB-1.jpg
The 4 Ni-MH regulate both voltage and allow excess current not used by the LED headlight and taillight to be used as recharging current when riding at night. They also set the proper voltage to meet USB power requirements. During daylight hours the lights are turned off with S1 and a USB cable pluged into the USB port allows operating and recharging the Palm TIX and a bluetooth GPS unit. The capacitor across the headlight is not necessary when the batteries are in the circuit but I included it so if my batteries were lost, damaged, or stolen I could still use the light with the dynamo.

You can upgrade the LED on the EL530? I already have one of these lights and while it's ok for lit roads, if I could add a second and upgrade the LED's that might be my best option. Where can I get the correct LEDs?

Thanks everyone else for the suggestions, but I think using my current EL-530 with a second and modifying their LEDs is the best option.

EL530 thread is here:
http://www.candlepowerforums.com/vb/showthread.php?t=167551

Led $5.80 here:
http://www.dealextreme.com/details.dx/sku.2026

I guess after upgrading the one you have you will have some idea if two will be enough light.

Most of the times you only need the maximum brightness when you're going downhills which may only be ~3-8mins down a hill then to level or hilly ground. Most of the time you'll be riding with ~50% light output or less to save power. Of course if it's foggy or raining then yah you'd want to crank the power up for safety or if you're a full power night hound better carry a LOT OF BATTERIES if you want full time full power.

I built lights from two of these, 3-18V CREE LEDs:
http://www.dealextreme.com/productimages/sku_6090_1_small.jpg
http://www.dealextreme.com/details.dx/sku.6090
I run them from a 14.4v lithium 4800 maH battery. They draw about 250 mA each, so get about 9 hours with both on or 18 hours with only one in use. One is enough if I'm not going too fast, and two will let me ride at a brisk pace. I have mine mounted on my forks; homemade, but plenty bright and long run time and cheap. I can also run them off AA or AAA batteries if I carry a battery holder with me (4xAA), since these lights can run off any input from about 3 to 18 volts DC.bikeforums.net/showthread.php?t=373642"]http://www.bikeforums.net/showthread.php?t=373642[/url]
Total investment was about $70 for the Li-ion battery and charger, plus $20 for the CREE lamps. I had all the wiring, tubes, and connectors lying around.

I have one of those in my headlight and I have to agree with him. To get the kind of runtime you're looking for you're going to have to go LED, and with those self regulating modules it's a no brainer. I say put 2 on the bar and one on your head and ride as fast as you want to. You'd be a little over budget, but if you ran three of those with the $85 14.4V 5000mah water bottle battery I bet you get the runtime and light you're looking for. Any halogen solution isn't going to run more than a few hours.

edit. I just checked batteryspace and they have the same battery with a cheaper charger for $75...

http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=3261

There is a solution for less than $80. I recently bought four Planet Bike Super Spots from http://www.amazon.com/s?ie=UTF8&keywords=Planet+Bike+Super+Spot+Headlight&index=sporting&page=1. The current price is less than $13 each with free shipping. I also bought four Seoul W42180U replacement LED's for the Luxeon III in the Super Spot at about $9 each but later I found out they are available for $5.80 each with free shipping from http://www.dealextreme.com/details.dx/sku.2026. That would be a total of $74.96.

Each modified Super Spot is good for about 100 lumens and a run time at full brightness of about eight hours. I use two at a time for about 200 lumens which is roughly equivalent to a 10 watt halogen. Four would be good for about 400 lumens or comparable to a 20 watt halogen.

I posted the description of how to do this at a web site called www.bcks.com. Search on "Improving the Planet Bike Super Spot".

Note that changing the 5.6 ohm resistor can significantly increase the light output at reduced run time.

There is a solution for less than $80. I recently bought four Planet Bike Super Spots from http://www.amazon.com/s?ie=UTF8&keywords=Planet+Bike+Super+Spot+Headlight&index=sporting&page=1. The current price is less than $13 each with free shipping. I also bought four Seoul W42180U replacement LED's for the Luxeon III in the Super Spot at about $9 each but later I found out they are available for $5.80 each with free shipping from http://www.dealextreme.com/details.dx/sku.2026. That would be a total of $74.96.

Each modified Super Spot is good for about 100 lumens and a run time at full brightness of about eight hours. I use two at a time for about 200 lumens which is roughly equivalent to a 10 watt halogen. Four would be good for about 400 lumens or comparable to a 20 watt halogen.

I posted the description of how to do this at a web site called www.bcks.com. Search on "Improving the Planet Bike Super Spot".

Note that changing the 5.6 ohm resistor can significantly increase the light output at reduced run time.

Interesting, would that be brighter than the EL-530? I know theres no real conversion between candlepower an lumens, and the cateye is listed in candlepower.

A unmodified EL530 is probably similar in performance to a unmodified Super Spot. They both use Luxeon LED's. Cateye may specify in candlepower but they use a Luxeon part which the manufacturer specifies in lm. and it is about 40 lm. at 350mA. I put links to the pdf datasheets of the Luxeon and Seoul emitters in the article I posted to www.bcks.com (http://www.bcks.com) web site. Be sure to get the part that ends with the "U". That part is selected for typical output of 100 lm at 350mA. which is more than double that of the Luxeon part at the same current.

Here is a thread in which the Luxeon in the EL530 was updated with the same LED I used to update the Super Spot.
http://www.candlepowerforums.com/vb/showthread.php?t=167551

You could probably modify four EL530's and get similar performance to four Super Spots. The problem is that the price of the EL530 seems to average around $42 where the Super Spot is $13 with free shipping.

P.S. I credit a guy named Dan for coming up with this. He posted what he did in the www.amazon.com reviews for the Planet Bike Super Spot. Dan replaced the internal 5.6 ohm resistor with a 2 ohm resistor boosting the light output to about 175 lm. but at a reduced run time of probably four hours. That is roughly the output of a ten watt halogen.

trhouse - Does this look like something you would be interested in?

2X Cree P4 WD bin LED's (spot beam) or 2X SSC P4 U bin LED's (flood beam) ~400 lumens
Anodized aluminum housing
7.4V 2400 mAh Li-Ion battery w/ protection circuit - ~3 hour run time
1.0 amp smart charger w/charging adapter cable - ~3 hour charge time
Trail Tech waterproof cable assembly
Weight of lighthead and battery - 173 grams

There is also a 7.4V 4800 mAh Li-Ion battery w/ protection circuit - ~6hour run time

PM if interested.


http://gallery.mtbr.com/data/mtbr/500/medium/ameoba2.jpg

http://gallery.mtbr.com/data/mtbr/500/medium/ameoba.jpg

http://gallery.mtbr.com/data/mtbr/500/medium/Amoeba_matte_silver_quarter.jpg

Here is my personal set-up for ~1000 lumens!

http://gallery.mtbr.com/data/mtbr/500/medium/ameoba5.jpg

http://gallery.mtbr.com/data/mtbr/500/medium/ameoba4.jpg

http://gallery.mtbr.com/data/mtbr/500/medium/ameoba3.jpg

JB01245,

Thanks for the offer but I am happy with the four Planet Bike Super Spots modified to give about 400 lumens for 8 hours. Total cost was about $80 and an hour of work. Most of the time 200 lumens is enough for me ( slow rider here! ).

You might ask Hocam.

JBO1245 I was wondering if you could post a pic of what the beam looks like for the single setup and the triple setup? I like the housing on the helmet. That is pretty cool.

JB01,

How the hell did you get the unit to be cut so clean? Check your PM.

That is some very high quality work there JB01245...

I built lights from two of these, 3-18V CREE LEDs:
http://www.dealextreme.com/productimages/sku_6090_1_small.jpg
http://www.dealextreme.com/details.dx/sku.6090
I run them from a 14.4v lithium 4800 maH battery. They draw about 250 mA each, so get about 9 hours with both on or 18 hours with only one in use. One is enough if I'm not going too fast, and two will let me ride at a brisk pace. I have mine mounted on my forks; homemade, but plenty bright and long run time and cheap. I can also run them off AA or AAA batteries if I carry a battery holder with me (4xAA), since these lights can run off any input from about 3 to 18 volts DC.bikeforums.net/showthread.php?t=373642"]http://www.bikeforums.net/showthread.php?t=373642[/URL]
Total investment was about $70 for the Li-ion battery and charger, plus $20 for the CREE lamps. I had all the wiring, tubes, and connectors lying around.

So, did you make your own housings? If so what did you use? Is it as simple as just mounting the LED into a housing and adding a switch? I would sure like some detailed info if you have it. I have several 6 volt NiCad and NiMH batteries, a smart charger and 4 MR-11 lighting heads (6-15 watt) that I've been using for years. This LED appears to be a simple and inexpensive way for me to try an LED light while still using the batteries/charger I already own. I know my way around with a volt meter, soldering gun, etc. but am pretty ignorant of the needs of an LED. Thanks for any input.

I jammed one into a headlight I had and am running it from the 3aaa batteries in that housing. Being that they're self regulating from 3-18V, it literally means you take any battery in that range and wire it in with a switch and it will work. They have a great output and nice spill too. I feel like a locomotive on foggy mornings. ;)

http://www.ovrrdrive.made2own.com/uploader/files/2/cree_3.jpg
http://www.ovrrdrive.made2own.com/uploader/files/2/cree_2.jpg
http://www.ovrrdrive.made2own.com/uploader/files/2/headlight_only.jpg

So, did you make your own housings? If so what did you use? Is it as simple as just mounting the LED into a housing and adding a switch? I would sure like some detailed info if you have it. I have several 6 volt NiCad and NiMH batteries, a smart charger and 4 MR-11 lighting heads (6-15 watt) that I've been using for years. This LED appears to be a simple and inexpensive way for me to try an LED light while still using the batteries/charger I already own. I know my way around with a volt meter, soldering gun, etc. but am pretty ignorant of the needs of an LED. Thanks for any input.

This LED with reflector and regulator is a pretty complete package. I put it inside a short metal tube, removed the contact springs, soldered wires to the solder pads, and that's about it. I had to add a front clear piece to keep dirt/rain out of the lens. I may try to improve the mounting later, but this is working well for me.

Anything from about 3.5 to 18 volts should work fine.

Eighty bucks... I'd start with adding up what you need and shopping from there.

IMO, three of the newer Crees or SSC's running at 500ma would be the minimum if you're planning on riding at higher speeds (not quite flat out, though) or in the rain at a reduced pace. They're a lot more efficient at lower amperages as well, pushing out well over half of the light you'd get at 1000ma for less than half the wattage. (500ma at 3.3 volts vs 1000ma at 3.6 volts) It's getting cheaper to underdrive and add an led so you can downgrade the battery you'll be needing a notch. Two led's focused tight for distance, one at 10 or 12 degrees for close up.

That would be around 5 watts, plus some losses in wiring and the controller, so I'd round it up to 6 watts just to be conservative.

6 watts by 8 hours = 48 watt hours. If you're using a lead battery, it's also a good conservative thing to double your estimated watt hour requirement to account for capacity loss due to cold and age, while still leaving a little buffer to get you home if you're out longer than anticipated. 96 watt hours ÷ 12 = 8 amp hours. Here's one that's close (http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=2147), at 7.5 amp hours, for $20. Batteryspace chargers run between $13-23. We're up to around $40, give or take, for lead.

Alternatively, you could take a step up to NIMH, all-battery has a pair of 7.2 volt 4.5 ah batteries with a smart charger for $71 (http://www.all-battery.com/index.asp?PageAction=VIEWPROD&ProdID=1891). That's 64.8 wh; ÷ 48 = 35% surplus capacity, which should be enough with a nickel battery to avoid dangerously deep discharges with some headroom.

So anyway, $40ish for lead battery (5.6 pounds) and charger, $10-12 per led/optic/controller(s), and $10 or so for shipping = Your $80 target budget if you dig up the absolute cheapest stuff you can find and figure out how to house and mount everything from scratch. It's possible, just barely. Just for comparison, you could bump up to a bigger lead battery to run a 10 watt mr16 for 8 hours for maybe five or ten bucks less and four to eight pounds more. led, ftw, imo.

Personally, I'd go for the nickel batteries (0.8 pounds). And I'd step up to a taskled controller for around $30. For about $130 you could have the option of a full power triple led light for the odd fast descent, then turn it down to 350ma through well lit areas or while trudging up hills to compensate.

Hi If you are not a DIYer then check out Fenix lights. I have the model that runs on 2AA NiMH batteries, 175 lumen, 2 hr burn time on high (more if you turn down the brightness). You could easily stash 6 other NiMH batteries in your pack. The light retails for $60.00. Non rechargeable batteries are cheap, $00.50 each. You will have to mount it to bars or helmet. They sell things called fish blocks but you could easily fashion something yourself. I mounted mine on my helmet with an old Viewpoint helmet mount from my old system.

There is a solution for less than $80. I recently bought four Planet Bike Super Spots from http://www.amazon.com/s?ie=UTF8&keywords=Planet+Bike+Super+Spot+Headlight&index=sporting&page=1. The current price is less than $13 each with free shipping.

Bah! It's up to $23 now. It couldn't last. I got one at $13, strapped to my helmet and awaiting the $6 SSC LED to upgrade it (after seeing your comments on Amazon), but reading this I was thinking of picking up another... No longer the storming deal it was.

Think it might be worthwhile putting in a controller rather than just a resistor? There seems to be space in there, and I'd like the option to have one flash, and perhaps have a more predictable brightness. I'd have thought that running it at continuous 1A would have heat issues, with the small heatsink encased in plastic, but I'm sure it could take it on some sort of strobe.

A pretty sophisticated Fenix bike mount is available or $15.

https://www.fenix-store.com/product_info.php?cPath=25_66&products_id=388


sping,

I have posted temperature tests with different resistor values for 1, 2, and 2.5 watts of drive to the LED at www.bcks.com. Search on "Improving the Planet Bike Super Spot". www.dealextreme.com has some current regulators available with flash mode but I have on order a fixed current one to experiment around with but the current determining resistor will need to be increased to limit the current to a lower value than the 800 mA specified or the LED maximum junction temperature will be exceeded.

One thing that my photos do not show well is that the Seoul part produces a broader light pattern than the Luxeon. I use two at a time, one for distance and one for close in.

Yes, I noticed the change in price, but the price has been bouncing all over the place on Amazon. It has been between $12.94 and $16.05 for months until now.

I have posted temperature tests with different resistor values for 1, 2, and 2.5 watts of drive to the LED at www.bcks.com (http://www.bcks.com).

Many thanks for these writeups... Great information. I'm looking forward to putting in the SSC emitter.

I'm a little confused - there's either a typo or have I just not read carefully enough (I was jumping around a bit). You say:


Testing at higher powers ... This first test used the original two ohm resistor ... +78 degrees C.. Light output is 100 lm. based on datasheet.Surely the lower output & temps would be from the original 5.6 ohm resistor? Isn't that what's it comes with?

By the way, based on your temps measurement, efficiency will be down at the higher temps - did you include that in your lumens estimates? I'll probably just swap the emitter and stick at that - with the excess heat there will definitely be diminishing returns for more current. It seems to be a light that's designed for 350mA or so.

I'm pretty pleased about an enlarged spot - I need it to be seen as much as to see.

It was a typo that is now corrected. Thanks for the proofreading! It should have been 5.6 ohms which is the original resistor. I plan to try a current regulator instead of the resistor since the 5.6 ohm resistor is dissipating 0.67 watt when the LED is getting 1.0 watt.

I did not factor in the efficiency because I can not reconcile the datasheet efficiency curve with what I see and you can see at the www.bcks.com (http://www.bcks.com) posting. Seoul only provides a curve of "relative light output" vs "junction temperature" at one current of 350 mA. If I use that curve, then at a junction temperature of 80 degrees C., the light output of 100 lm should be reduced to 88 lm. and if at 570 mA the junction temperature is 120 degrees C., the light output of 140 lm should be reduced to 109 lm. 109 lm. is about 24% more than 88 lm., but the photos and my own experience seem to indicate that the difference is greater. I am not sure if that means the efficiency curve is also a function of the current but there is data for only 350 mA.

The second modification I did resulted in a narrower beam than the first. I may post that comparison as well. I used it to my advantage by aiming the narrower, more concentrated beam farther out and the broader one closer in.