DIY Cree LED bike light

[mountain_lion]

 

Some may remember my post in Willehond's DIY light thread featuring a very nice heat sink.

 

I decided this heat sink deserves to be used in a killer light.

Something like a triple Cree XR-E Q5. Luxeon IIIs are old hat...

 

So I sourced some Cree LEDs and lenses from China:

 

 

I found that the lenses & LEDs were a good fit in 22mm brass end caps.

Heavy, but good heat sink and easy to construct (lathe not required), so I built this monster:

 

 

 

 

Very bright light (much better than the Luxeons) and the beam distribution is not bad either; some useful spill light to light up the side of the trail.  (Beam shots to follow in another post).

 

So this experiment proved to be a success and I now had a bright light to use while figuring out how to turn the PC heat sink into a killer bike light.

 

 

mountain_lion2008-09-22 16:32:29

[Willehond]

Jou bliksem! Very nice.  Looks stunning and I like the brass end caps.  Can't wait for the beam shots!

[mountain_lion]

Finally I had all the parts ready:

 

 

The PVC pipe and modified coupling method worked fine to enclose my original Luxeon LED light, so I decided to use it again.

 

 

I machined an Al disk to fit into a 50mm PVC pipe, with holes drilled and threaded to mount the LEDs and fit the legs of the lens:

 

 

 

Much easier to mount this onto the heat sink than working direct on the heat sink. While the disk on its own might provide sufficient heat sinking, the round heat sink has much more bling value, so had to be used.

 

 

The LEDs are secured with heat sink paste and screws.

 

 

This assembly is then screwed onto the heat sink (with some heat sink paste in between).

 

 

Lens goes on top and is secured with a modified PVC coupling to serve as fixing ring. This required quit a bit of work on the lathe since the coupling's diameter had to be reduced to fit inside the heat sink fins. Not much space between the PVC pipe and the heat sink either.

 

 

I modified some scrap Al extrusions into a mounting bracket with some foam to protect the stem plate on the bike.

 

 

I am still experimenting with the mounting; using a LED flasher mount on the under side of the stem at present.

After some mods including a rubber band for stability, it is working OK, but I am not 100% satisfied with this solution yet.

 

I ordered a blex driver from http://www.taskled.com (George is a very helpful guy).

 

With this design there is no space for the driver in the light head, so I enclosed the bflex in a small plastic container used for cosmetic samples, complements of the local pharmacy).

It is packed with some foam with a tact switch on top protruding through a hole drilled in the lid.

 

 

 

 

(I will hard wire the light head to the driver later, but for now it is convenient to be able to plug various light heads onto the driver).

 

The driver enclosure is covered by a piece of old bike tube with a button (from army days) sewn on with dental floss. To attach, just wrap around the handle bar and hook the button through the "button hole" on the other end of the tube.

 

 

I am using 14.8V Li-ion Batteries which are attached to the bike frame in a small pouch with a velcro strap.

 

All mounted on the bike:

 

[mountain_lion]

 

 

 

And now for the beam shots (air drum roll http://fc95.deviantart.com/images2/i/2004/02/d/3/Air_Drummer_emoticon_2.gif)...

 

All photos with Panasonic FZ20 set to auto white balance.

4 seconds @ F4, ISO 100.

 

The tree in the foreground on the right is 14m from the garden shed.

Lights and camera on tripod are 2m back from the tree, which makes it 16m from the light to the garden shed. (yes I know I need more distance to really show this light, but it is much easier doing these photos in my back yard).

 

 

First my original Luxeon III LED light:

 

 

 

2x Luxeon helmet light:

 

 

 

The 3 individual Cree's (all 8 degree lens angles):

 

 

 

Triple Cree in round heat sink:

 

 

 

mountain_lion2008-09-22 17:02:59

[mountain_lion]

The beam shots above does not show it well, but the combination triple Cree lens gives a better result than the 3 individual lenses.

 

The beam pattern can be seen better from a side view against a flat surface (like my dining room wall):

 

3 individual Cree's:

 

 

 

Triple Cree in round heat sink:

 

 

 

As can be seen here, the composite lens (sourced from deal extreme) gives a nice narrow spot to light up the road ahead (about 10? ?), but also has usable side spill of 30? +.

 

The 3 individual lenses has a wider total beam, which spreads the light over a wider area, so it seems less bright.

 

I am not sure if I will even need the helmet light with this light.

Will have to go ride some really twisty single track at speed to see...

 

 

[Thug]

Very nice Mountain Lion & well done. Looks very impressive and all at at reasonable price.

 

Those Cree's will certainly blind any oncoming traffic !

 

[1hill@aTime]

you need to mow your lawn...

 

p.s nice lights

1hill@aTime2008-09-23 00:18:43

[markStockton]

 

Very, very, very nice. I think it is time to upgrade my light. Where did you get the LED's and lenses? Did you use the same Buckpuk?

 

[Shebeen]

brass endcaps?nice thinking. are they for plumbing, and can you get an o-ring in there to seal them?

 

 

[Willehond]

Wow, that shed is almost too bright to look at!  I still like my Luxeon setup because it's way better than any sub-R1000 light setup, but it literally pales next to the CREE.  I will join mark in the upgrade war!  I must have (winter is almost here for me!).  The one thing I will need is a dimming mechanism because you will NOT be popular in traffic with that thing on full blast

 

What is also quite amazing is that it runs off the same controller and batterypack!  The Cree is obviously way more efficient, but how does the heat buildup compare to the Luxeons?  Bliksem, I am starting to drool again...

Willehond2008-09-23 00:31:14

[mountain_lion]

Blfex driver has 5 brightness settings. You can operate it in 5 level mode or duo mode (2 setting). For duo mode you can choose any of the 5 levels for the 2 you use.

No problem dimming.

 

But who needs to dim off-road?

 

At 680mA load current at full blast (level 5) the theoretical run time from 2200mAh is more than 3 hours (still need to test the actual run time from this battery).

 

 

PS: It has been too wet in the Western Cape to mow the lawn, and when the weather is good, I grab the opportunity to go for a dryer ride! 

 

 

[Willehond]

That is at 680mA!?  Wow

[Marius]

Nice going ML!!! HOW MUCH did it cost to build the two brighter lightes?/ Lilo needs a bright light but at a affordable price you see's.

[mountain_lion]

 

Wow' date=' that shed is almost too bright to look at!  [/quote']

Shed was varnished in preparation for winter a few months ago...

 

What is also quite amazing is that it runs off the same controller and batterypack!  The Cree is obviously way more efficient' date=' but how does the heat buildup compare to the Luxeons?  Bliksem, I am starting to drool again...

[/quote']

 

The driver only cares about the forward voltage of the LEDs, which is similar for the Luxeons and Crees. Both LEDs can handle up to 1A with ease, provided you have sufficient heat sinking.

 

Because the Crees are much more efficient, they provide more light and thus LESS heat @ the same input power.

That round heat sink is total over kill. Only gets slightly hot to the touch when used indoors with no airflow.

 

 

[mountain_lion]

 

That is at 680mA!?  Wow

 

680mA load current @14.8V from the battery.

1A drive current through the LEDs.

 

 

[Willehond]

Nice going ML!!! HOW MUCH did it cost to build the two brighter lightes?/ Lilo needs a bright light but at a affordable price you see's.

 

Give her your fancy one and build yourself this one.  That's what a real man would do  Anyway, that little one you usually have on your helmet will disappear in the CREE light.