Build thread - double XM-L road lights

Note: thread put on MTBR as well so apologies to anybody who uses both forums!

Following on from this thread on MTBR on road friendly light design I'm making a pair of lights for road use. The aim is to put more light on the road and less in the air than with the standard reflectors and optics we use. The way I'm doing this is by using half a reflector with the LED firing down into the parabola, best illustrated by the following diagram from the aforementioned thread:

Each light contains one XM-L and the pair operate together, with a single LFlex in one light driving both lightheads. The lightheads are made from 1.25 inch 16AWG aluminium tubing and are mounted beneath the handlebars to keep out of the way. Battery power comes from 4 * 18650 cells from DX.


After much trial and error here's the donor for the reflectors (my wife's old halogen bike light):



Here are (most of) the parts for the two lightheads



I've kept them as two lights for the sake of extra heatsinking per LED, and yes, for aesthetics! There's an additional heatsink on the bottom of the lighthead with the LFlex. Here's a mock-up of how the internal parts fit inside, although in reality there will not be any overlap of the two L-shaped sections. The LED is mounted on the inside of the main tube, firing down into the reflector.



Here is a further indication of how things fit together:



And finally here as a taster is a beamshot of one of the reflectors on a testbed. First shot is the control, second is the XM-L through a Regina reflector and third is with one of the cut reflectors from this build. Distance to the fence in the background is approximately 17 metres or 55 feet.
Control:



Single Regina reflector:



Single road reflector:

Pretty nice work, and nice documentation!

I'm looking at (eventually) mod'ing an old Cateye Micro II, and hadn't thought of using the original reflector and optics. They weren't the best to start with, but might still be fun to experiment with. I've also got a dead BiSy dynamo light with rather good optics/reflector, and it would also be a good place for a LED modification.

Do you have any pics of the LED mounted into the reflector?
Any comparison of the LED conversion to a dynamo light that meets the German standard?
What's the beam width of the Regina reflector? I'm trying to understand if the LED mod has a tighter beam due to the intrinsically tighter beam of the reflector.... or is it due to the choice of where the LED is placed relative to the reflectors focal point?
..so many questions, eh?

Steve K.

Nice. Any chance you could get beam shots against a white wall? It is hard to tell if the beam distribution is better (ie, brighter at the top, with a sharp cutoff), or if the beam is just tighter.

I'm afraid I haven't any pictures of the LED mounted in the tube yet - fixed it a couple of days ago and will hopefully be fixing the reflectors this evening. The Regina reflector is +-4 degrees with XP-E and +-5 with XP-G, but it's certainly more than that with an XM-L due to the size of an XM-L. The road beam above is tighter because the cut reflector is part of an approx. 50mm diameter reflector rather than the 20mm diameter of the Regina. That means it has quite a bit more throw. However the mounting of the LED (i.e. firing straight down into the reflector) also plays a significant part, and means that most of the light is guided by the reflector onto the ground with much less emitting above the beam.

I haven't any comparison with lights that meet the German standard as I don't have any! If I did I would probably have butchered it up by now to fit more powerful emitters ...

Matt, I'll try and put white wall shots up when I've finished the lights. In the meantime you can see my experiments with reflectors in this thread http://forums.mtbr.com/lights-diy-do-yourself/road-friendly-light-design-686146.html, and there are some white wall beamshots there. The beam is brighter at the top with a sharp cutoff - it's basically a tight hotspot with spill down but not up.

More pics as I progress the build (hopefully this weekend).

I think I was under the impression that this was intended to produce a better beam pattern than off-the-shelf optics and reflectors. In the sense that a larger reflector does produce less spill (or at least it can), then it would be an improvement. I'm not sure that it has an advantage over a narrow beam optic that is designed for the chosen emitter. However, it's not always easy to get a good optic for the chosen emitter! I've been trying to find a specific Ledil optic for a Cree XP-G, and I'm having no luck at all.

I think the optimal solution is to use optics similar to dynamo lights designed for the German standard. This puts very little light into the eyes of oncoming traffic, little light right in front of you, and most light ends up much further down the road. The goal is to get a large portion of the road illuminated evenly, so that the road 100 feet (or more?) ahead is just as visible as the road 10 feet in front of you.

With conventional optics, I can approximate this by having a very tight beam that is as wide as the road 50 feet in front of me (roughly) and the little bit of spill lights up the road nearby and provides some visibility to the sides. There have been some LED lights produced that use optics that meet the German standard, and these would be a great starting point for a modification! I just need to find someone who has one that died and would donate the remains to me.

Steve K.

Steve K said:

There have been some LED lights produced that use optics that meet the German standard, and these would be a great starting point for a modification! I just need to find someone who has one that died and would donate the remains to me.

Click to expand...

Or you can buy this light
http://www.dealextreme.com/p/xc-997a-3w-3-mode-1200-lumen-white-led-bike-light-4-x-aa-82138
The original LED is the same size as a XP-G.
And the original LED current is approx 350mA


/Håkan
SWEDEN

Steve K said:

I think I was under the impression that this was intended to produce a better beam pattern than off-the-shelf optics and reflectors. In the sense that a larger reflector does produce less spill (or at least it can), then it would be an improvement. I'm not sure that it has an advantage over a narrow beam optic that is designed for the chosen emitter. However, it's not always easy to get a good optic for the chosen emitter! I've been trying to find a specific Ledil optic for a Cree XP-G, and I'm having no luck at all.

I think the optimal solution is to use optics similar to dynamo lights designed for the German standard. This puts very little light into the eyes of oncoming traffic, little light right in front of you, and most light ends up much further down the road. The goal is to get a large portion of the road illuminated evenly, so that the road 100 feet (or more?) ahead is just as visible as the road 10 feet in front of you.

With conventional optics, I can approximate this by having a very tight beam that is as wide as the road 50 feet in front of me (roughly) and the little bit of spill lights up the road nearby and provides some visibility to the sides. There have been some LED lights produced that use optics that meet the German standard, and these would be a great starting point for a modification! I just need to find someone who has one that died and would donate the remains to me.

Steve K.

Click to expand...

It is exactly intended to produce a better beam pattern than off-the-shelf optics and reflectors. My comment about reflector diameter was purely to explain how it also has much better throw than the standard reflector I compared it against. But the goals you mention are exactly those that I am seeking to achieve, and hopefully have (to an extent) here.

Optics from the Philips Bike Light (or dyno equivalent) would work very well, and of course I'm using the same principles here. The light HakanC has posted a link to would undoubtedly make a good donor for a reflector.

By the way, the Regina reflector is XP-G specific if it helps you?

Sent from my GT-I9100 using Tapatalk

HakanC said:

Or you can buy this light
http://www.dealextreme.com/p/xc-997a-3w-3-mode-1200-lumen-white-led-bike-light-4-x-aa-82138
The original LED is the same size as a XP-G.
And the original LED current is approx 350mA


/Håkan
SWEDEN

Click to expand...

I would have to see some evidence that it meets the German standard first.

Steve K.

mfj197 said:

.....

Optics from the Philips Bike Light (or dyno equivalent) would work very well, and of course I'm using the same principles here. The light HakanC has posted a link to would undoubtedly make a good donor for a reflector.

By the way, the Regina reflector is XP-G specific if it helps you?

Click to expand...

I've got a incandescent BiSy dynamo headlight that was donated to my cause. It died of something, which shouldn't be a problem for a LED conversion. I just need to find some time.

Regarding the Regina reflector.. I'm partial to the molded optics, mostly because there is less light wasted as spill. It may be a good option to have, though, if I can't find the proper molded optics.

thanks,
Steve K.

Lights now painted and (mostly) assembled. The reflectors are installed, LED wires potted and wiring complete. Still have to:

• Cut out and glue in place lexan front covers
• Affix LFlex to inside of light
• Push switch through back cover and screw on waterproof cover
• Fix back covers and cateye spacer mounts, and waterproof back cover with silicon

I'd quite like to put a small sheet of rubber in between the cateye spacer and the light for grip and waterproofing - do you guys bother? Also the biggest problem I have is in affixing the LFlex to the inside of the light as the adhesive on the thermal pad isn't strong enough and the wiring keeps on pulling it away. Do any of you have that problem?


The unpolished insides of the tube reflect a good amount of light wide to the sides, good for being seen from near side on.


Here's a shot showing the LED and reflector mounted inside the lighthead:



All wired up and functioning:



White wall beamshot on low.

that's a really nice build! I get alot of high beams back in the face when I ride around with my DX XML bikelight....

kenwood96 said:

I get alot of high beams back in the face when I ride around with my DX XML bikelight....

Click to expand...

Sorry for hi jacking this thread.
But I also use the DX XML bikelight and there is an easy and cheap way to reduce glare for oncoming traffic without reducing the light output too much.
It is the mentioned here: http://www.candlepowerforums.com/vb...t-light-beam&p=3381661&viewfull=1#post3381661
It shows a method of reducing glare for oncoming traffic by redirecting the
light with half a diffuser glued to the front of the light glass.

But I also wanted a wider beam, so I ordered a wide angle lens from dapedaler on ebay
http://cgi.ebay.com.sg/Wide-Angle-L...ltDomain_0&hash=item45f9ea505e#ht_1873wt_1139


I epoxied the half diffuser to the front of a wide angle lens.
I also painted the half diffuser with silver paint, like this



Before



After


Please Note
My very simple fully automatic camera exaggerates the diffrence.

A modified light like this may reduce glare for oncoming traffic, but the light beam is in no way as good as with a dedicated reflector as in this thread.
(I also use the Philips battery LED light http://www.candlepowerforums.com/vb/showthread.php?287452-Philips-LED-bike-light)

the beam look good, the light itself ....

Here's some photos of the completed lights on the bike.

mfj197 said:

The light HakanC has posted a link to would undoubtedly make a good donor for a reflector.

Click to expand...

DX now have a cheaper version of XC-997A http://www.dealextreme.com/p/xc-997a-3w-3-mode-1200-lumen-white-led-bike-light-4-x-aa-82138
it is called XC-997B http://www.dealextreme.com/p/xc-997b-cree-3w-200lm-3-mode-white-led-bicycle-bike-light-4-x-aa-108640
The only difference is that the charger is not included (and maybe the batteries).