Want to build bike light - question about wiring LED driver + Cree LED

[heyjaffy]

I've been making halogen-based bicycle lights for the past couple of years, and wanted to try to make a couple LED-based lights this year. I got a tip on http://www.bikeforums.net that dealextreme.com was the place to go for materials.

Without doing a ton of homework, I hit dealextreme and ordered a few of these drivers and LEDs along with some optics/housings. Here's what showed up yesterday:

I was thinking there might be wiring diagrams, instructions, or at least an intuitive solution as to how to power the drivers, and then connect them to the LEDs, alas, I thought wrong. So, I have a couple of questions:

* Where do I connect power to the driver? I'm assuming it's to the underside, + and - being the circles on the bottom, but they're not labeled. I blew a fuse in my multimeter and am having a problem finding a replacement, so I don't have the means to do a continuity test at the moment.

* How do I connect the driver to the LED? I'm assuming it's the + and - lead coming off the driver, but the LED has two + and two - connection points, and I'm not sure if it matters which ones I use.

* Bonus question: I'm not sure if I want to make a couple single-LED lights or one 3-LED light. If I want to use 3-LEDs in one light, do I need to use 1 driver per LED, or can I use 1 driver for all 3 LEDs?

Oh, in case it matters, I plan to power the light with a 7.2v 3500mAh NiMH battery.

 

[dom]

Hi Hey
:welcome:

http://forums.mtbr.com/forumdisplay.php?f=124
http://candlepowerforums.com/vb/showthread.php?t=169531

A couple of places to start - many homemade lights.

Probably one of the most comprehensive places to start is Allens AKA Nightrider's site

http://bikeled.org/

The Batt + is in the middle of the driver, - on the outside.
You join the driver to the 2 closest together pads on the LED.

Probably not the best way to go having 3 drivers and especially those type if they are the ones with a bunch of modes.
You'll be riding around more in the dark as you try to get a light level you need and having an epileptic fit when you hit the stobe

Alot of people use buckpucks or single level 700ma cheapo drivers or the Roll's of drivers ,bFlex or maxFlex,for their bike lights.

Check out the links and do a bit more research -especially Nightriders.

Cheers
Dom

 

[heyjaffy]

Alot of people use buckpucks or single level 700ma cheapo drivers or the Roll's of drivers ,bFlex or maxFlex,for their bike lights.

Many thanks Dom - I'm continuing to do a lot of reading and am wising up to the concept of the buckpuck vs. the drivers that I picked out, as I'm strongly considering a 3-LED light. You mentioned 700mA drivers - is there a reason to go with 700mA vs. 1000mA? The Cree LEDs that I have will take up to 1000mA - I'm looking at these buckpucks from ledsupply.com, and I want to make the right choice between the 700mA and 1000mA.

 

[dom]

Hi Hey
Check out Allens site -he knows more about the buckpucks -uses 3021's

http://bikeled.org/elec_LED.html

I use bFlex or maxFlex as you can have a momentary button for light control.


The difference between 700 and 1000ma is not much extra brightness,more heat and less battery runtime when running at 1000ma.

That's why i like the bFlex/maxFlex -you can choose whatever max current you want anytime.

Cheers
Dom

 

[dom]

If you are only going with the 7.2V batteries,then your choices for a driver is more limited unless you run the LEDs in parallel which is only recommended at low currents.

A maxFlex would be a good option with those batts and you can run the LEDs in series at great efficiency.

Do you want variable light levels?


Cheers
Dom

 

[heyjaffy]

I have 12v and 14.4v batteries that I could also run, if they're a better choice. I was limiting myself to 7.2v initially because the driver that I had selected was rated for up to 8.4v. Now if I'm going with a buckpuck or bflex/maxflex, I guess I can use the 12v or 14.4v batteries. Adjustable light levels aren't really a concern, so I need to know that there's another advantage to going to the bflex or maxflex.

 

[dom]

Using the maxFlex you can use 7.2V for 3 LEDs in series 12v for 4 LEDs

Using the bFlex you would use 14.4V for 3 LEDs -you could use 12V but wouldn't have much overhead -so very little runtime at higher current.

They both have user settable medium/low voltage warnings and temp setting.

Not sure what the buckpucks have in the way of voltage/temp warning -but if not worried about that would be good enough i suppose -alot of people use them.


Cheers
Dom

 

[heyjaffy]

Using the maxFlex you can use 7.2V for 3 LEDs in series 12v for 4 LEDs

Using the bFlex you would use 14.4V for 3 LEDs -you could use 12V but wouldn't have much overhead -so very little runtime at higher current.

They both have user settable medium/low voltage warnings and temp setting.

Not sure what the buckpucks have in the way of voltage/temp warning -but if not worried about that would be good enough i suppose -alot of people use them.


Cheers
Dom

Thanks for all of your help Dom - now that I've done more reading, something I should have done in the first place, I realize how silly some of my questions probably sound. I decided to use the 3 LED's, in serial, with a buckpuck, wired with potentiometer, and my 12v or 14v battery. I wasn't initially thinking about wiring up in serial, and having to add up the voltage draw of each LED. Thanks to your help and links, I'm starting to see the light... will post an update once I get this thing built.

 

[dom]

No worries mate.
There is alot of info out there and sorting thru it can be a major task. It sounds like you are on the right track.

People find using the pot can be a bit cumbersome but if you won't be using it constantly it should be ok.

Cheers
Dom

 

[dom]

There is a good drawing in post #12 for the 1000ma 3023 buckpuck using a resistor.

http://forums.mtbr.com/showthread.php?t=404713

 

[R290]

good stuff here. Dom you mentioned the 3021 drivers Are these better with heat dissipation?

 

[dom]

Hi R290
I really aren't any type of expert on the buckpucks,but i don't think they suffer from any heat issues as they are totally potted.

The heat you have to worry about is from your LEDs

Cheers
Dom

 

[R290]

Hi R290
I really aren't any type of expert on the buckpucks,but i don't think they suffer from any heat issues as they are totally potted.

The heat you have to worry about is from your LEDs

Cheers
Dom

I just watch the 2 videos from Analog by design good stuff for a newbe.

In their lab they show two of the same LED's and power supplies, but one without a heat sink. I thought this would only cause shorter LED life, but in fact the LED without a heat sink was almost half the lumen's of the one with a heat sink. There is webbench for power controller design, cool, as you pick the LED and how many, ect. all the way to buying the kit of parts needed to build your design. But understand hayjaffy has most of his parts
I download the design software from http://www.futurelightingsolutions.com/ This allows you to pick the right sized heatsink. Still waiting on a trial license. These are for Luxeon LED, but would still help in figuing out how big of heat sink is needed for 3
Cree XR-E Q5 Emitter on Premium Star (228LM at 1A) Hopefully a spare CPU heatsink will work. Maybe the flashlight guys have some input on this.

Edit.. Just bought a BuckPuck: 3021-D-I-1000 and the wiring plug with the exrternal pot to adjust it. The 3023 are not adjustable, plus a few other features missing.

 

[ifor powell]

A 50% drop in flux sounds high to me I just looked at the cree datasheat and they have a graph that looks to be about 67% for 150 degree junction temp as opposed to the base line 25 degrees. The graphs for 350ma anyone know if it's radicaly different for different curents?

Tempreture should not be too big a concern with a bike light, so long as you has a good path from the leds to a metal enclosure then in real use with pleanty of airflow things are OK. The real danger is testing indoors with no airflow. For a home made light so long as you are aware of this then everything should be ok. For a comercial light I can see it being very aukward for the manufacturer, they realy need to do somthing to protect there dumb users. Of course with the newer task led drivers you can get good thermal control in your home made light.

Ifor

 

[Calina]

To moderator...

Please, could this thread be moved to the proper forum (bicycle)?

 

[LukeA]

Hi R290
I really aren't any type of expert on the buckpucks,but i don't think they suffer from any heat issues as they are totally potted.

The heat you have to worry about is from your LEDs

Cheers
Dom

Buckpucks also aren't subject to mechanical problems either.

Yeah, drivers aren't a real source of heat. They're typically 75-95% efficient, while the LEDs are up to 40% efficient.

 

[R290]

To moderator...

Please, could this thread be moved to the proper forum (bicycle)?

I guess there needs to be a sticky stating what can be post here, sure looks like a homemade light to me Sure it might be going on a bike. A lot of post here are related to maglite, and there is a whole section for flashlights

I think people miss the sub forums and thats how they get here

 

[yellow]

To moderator...
Please, could this thread be moved to the proper forum (bicycle)?

I'm afraid I am, again, near to get my usual one-week muting in this forum, but
"man this post is soooooo silly"!
Why dont You just NOT read it?
its an electrical question, possibly good for quite a number of ppl, not really "bike" related, as its general multiemitter wiring.



back to what I remember from the questions:
imho these drivers are multimode-drivers?
No good idea to wire them in series, because You will end up with them not being in the same mode.
Multiemitter needs wiring in series + driver that depends on battery.
that 7.2 V batt is as good as any, just You will need a step-up driver (SHARK from sandwich shoppe, or FATMAN or MAXFLEX from taskled)

better not use a poti for the output, because one can never be sure on the output chosen (You will end up without spice in the batt because more current than estimated will be consumed).
The better way were to measure a few levels with the poti, then have a three/four way switch and make fixed values with the resistances measured for Your levels.
By doing so, You know exactly what current the light runs on and thus be on the safe side.

 

[R290]

I've been making halogen-based bicycle lights for the past couple of years, and wanted to try to make a couple LED-based lights this year. I got a tip on http://www.bikeforums.net that dealextreme.com was the place to go for materials.

Without doing a ton of homework, I hit dealextreme and ordered a few of these drivers and LEDs along with some optics/housings. Here's what showed up yesterday:

I was thinking there might be wiring diagrams, instructions, or at least an intuitive solution as to how to power the drivers, and then connect them to the LEDs, alas, I thought wrong. So, I have a couple of questions:

* Where do I connect power to the driver? I'm assuming it's to the underside, + and - being the circles on the bottom, but they're not labeled. I blew a fuse in my multimeter and am having a problem finding a replacement, so I don't have the means to do a continuity test at the moment.

* How do I connect the driver to the LED? I'm assuming it's the + and - lead coming off the driver, but the LED has two + and two - connection points, and I'm not sure if it matters which ones I use.

* Bonus question: I'm not sure if I want to make a couple single-LED lights or one 3-LED light. If I want to use 3-LEDs in one light, do I need to use 1 driver per LED, or can I use 1 driver for all 3 LEDs?

Oh, in case it matters, I plan to power the light with a 7.2v 3500mAh NiMH battery.

Can't find where you got your optics, could you post a link please.

Thanks

 

[A123Powered]

R290, those look like these DX optics:
http://www.dealextreme.com/details.dx/sku.11922
http://www.dealextreme.com/details.dx/sku.11921
http://www.dealextreme.com/details.dx/sku.1913

I have both types from DX, and the diffused optics seem to loose a good deal of intensity, but the individual lenses can be rotated to the best orientation. The aluminum reflector is seemed too tight for a bike light, but great for a flashlight. Their quad CREE lens worked pretty well for a bike light:

http://www.dealextreme.com/details.dx/sku.1915