What components for bike lights?

[Lazgoat]

Hi all, first post here.
I want to build myself some high power LED lamps for night riding. I have some Luxeon K2 LED's somewhere but I've seen some very impressive beamshots of the Cree XR-E's. Where can I get some of these?

Can you also suggest a good board to use and where to source it.

For batteries I'm thinking of getting a 7.2V 4000mAh Li-Ion pack from Batteryspace. Its nice and cheap, any reason not to use it? I'd like to get about 2-3hours use out of the lights, should I be looking at higher voltage batteries?

Thanks.

 

[jch79]

You can get Cree XR-E's from the Group Buys forums here at CPF, or at Cutter Electronics:

http://www.cutter.com.au/

You can get converters at the Sandwich Shoppe (Wayne, aka dat2zip has a forum here), http://theledguy.chainreactionweb.com, or CPF member goldserve makes variable brightness boards called FluPIC that have a strobe option as well.

As for batteries - I suppose it depends on what sort of bike light you want though - a commuting light that I use, if I could get a 4000mAh 3.7 volt battery like you mentioned, it'd charge my strobing light for... I don't even know how long, but a long time. Too bright a light, and you end up causing more trouble by blinding drivers, pedestrians, and other bikers - not a good thing!

If you want a really bright light for mountain bike riding or rural riding, I'd say that the 4000mAh 7.2 volt battery pack sounds pretty damned great! That'd put out some serious light at some serious runtimes! The 7.2 volts does bring up some concerns in that some boards cannot handle that... see the board specs for that before you buy things!

To me, the advantage of LED in bike lights is that they're efficient enough that you don't need an external battery pack, so something smaller might be something to consider. But if you want a burner like you're talking about (4000 mAh used in 2-3 hours), you're probably looking at an external battery pack.

Hope that helps!
john

EDIT: Welcome to CPF!!!

 

[Lazgoat]

hi John, thanks for the info. and welcome!

I will be using the lights solely for off road mountainbiking as I have commuter lights already.

So from what you have said should I be looking at a converter board that offers constant current rather than constant voltage? Would the 7.2V be an issue as I want to drive 3 x Cree's off the handle bars and then get a separate small torch/lamp for my head. An external battery pack doesn't bother me as I'll mount it on the frame.

 

[Sawtooth]

Hi all, first post here.
I want to build myself some high power LED lamps for night riding. I have some Luxeon K2 LED's somewhere but I've seen some very impressive beamshots of the Cree XR-E's. Where can I get some of these?

Can you also suggest a good board to use and where to source it.

For batteries I'm thinking of getting a 7.2V 4000mAh Li-Ion pack from Batteryspace. Its nice and cheap, any reason not to use it? I'd like to get about 2-3hours use out of the lights, should I be looking at higher voltage batteries?

Thanks.

Forget about the K2s -- use 3 Cree LEDs instead. See group buys or dealers corner on this forum.

If you want a simple continuous variable brightness potentiometer control, use LuxDrive BuckPuck (3021 with external pot as I recall). (ledsupply.com and many other places have these).

If you want a button-press type control to switch between various brightness levels, use bFlex from www.taskled.com (they are also planning a bike-specific user interface to be released soon).

For host, you can use a Mag D or Mag C -- get Modamag's heatsinks at the Sandwich Shoppe.

For battery pack, I'd use a 5200 mAh 14.8V Li-Ion pack (with protection board and fuel gauge) from batteryspace.com (or other places have them too). Batteryspace also has waterproof cables and connectors...

 

[Sawtooth]

Here is a description of a Mag Tri-Lux I built as a bike light. Ive built a few of these and Im working on Tri-Cree and Quad-Cree versions now...

http://www.candlepowerforums.com/vb/showthread.php?t=114903

 

[jch79]

I think Sawtooth's link is great - also Weedle just posted a Tri-Cree bike light he made with a Mag head and an external battery pack. As for converters, it seems like people are using the Shark converter for such beasts, however I'm NO GOOD in that department!
john

 

[greenLED]

Check the links in the following thread for more ideas:
http://www.candlepowerforums.com/vb/showthread.php?p=1755372#post1755372

Just today there were a couple of very nice builds posted.