Cool idea

[Whiplash]

I had this idea for my bike, I saw someone else here do it too. But I want to mount this.

http://cgi.ebay.com/SSC-P7-D-BIN-LED-Emitter-3-25V-3-5V-/320480341924?cmd=ViewItem&pt=US_Flashlights&hash=item4a9e1defa4

to my front Head Tube as the headlight. I think it will work great even wothout a reflector due to the 900 lumens it produces. I plan on having a seperate pack for the headlight, as it does draw a bit of juice. My question is this: Can I just wire this to a switch directly wired to the 5000mah pack without any circuitry? I am not too sure hoe LED's work and I don't want to burn up a 10 dollar bulb over stupidity. I also don't want a big ugly board on the front of my bike either. Anybody knw if this will work?

 

[Rifle]

If I'm not mistaken even if you have a 3.5v source you're going to need some form of circuitry to limit the current to safe levels. Also, those P7's don't usually actually put out 900 lumens. They are cheaper here ( http://www.dealextreme.com/details.dx/sku.11809) and if you search for SSC P7 you'll get a lot of other options, such as one that come w/ a heat sink, reflector and driver for only about $17 shipped. Seems to me going w/ out a reflector would be silly.

 

[Whiplash]

OK I will check em out, I have seen it done without a reflector with good success, it looks real clean when you don't have a big-ol reflector hanging off the front of the bike, but I could probably make it look OK with one Thanks for the link!

 

[Whiplash]

OK, I found out I need a heat sink for sure, but what about using the frame? I really like the idea of just the LED without the reflector, but it would only make sense if I could use it without a circuit board because that would just be ugly out front.Does anyone know for sure if I can just hook this up to power directly or does it need a current limiter to prevent it from burning up? I always thought elec. stuff would only draw what it needs if you got the volts right, but this could be different.

 

[evblazer]

A incandescent light bulb will draw a constant current and many electronic devices designed to do so will draw a specific amount but a bare led will eat the amps that are thrown at it and go up in a poof of smoke.
Ultracheap might be figuring out the right resistor to limit current between it and your power source.

 

[Whiplash]

I actually think I found a little combo unit that has a reflector and all but is very small for one of the little flashlights this LED is designed for. I am thinking the housing is metal, so I could just machine a little cup for it to thread into. Could be very sweet! This is for my prototype bike, not the cheap Schwinn.. Thanks for the help, if the setup I am looking at does not work i will try the resistor...

Here is what I found, thanks to the member that sent the link to me for these lights!

http://cgi.ebay.com/SSC-P7-D-1-mode-module-26-5mm-flashlight-/170506560322?cmd=ViewItem&pt=US_Flashlights&hash=item27b2fba342

 

[evblazer]

That drop in module should already have either a simple circuit or resistor to limit the LED since it mean meant to just be used in a flashlight so you should be good to go if you feed it within voltage specs.

 

[ebent]

I got one of theese http://www.amazon.com/Light-Motion-200L-Li-ion-System/dp/B001FVEZ7W It gives a lot of light, a modest draw, full, half or strobe. Can be bought without a battery. Best way to go. Buy a converter instead. We got the juice! Very light weight and small. Easy to mount. On the pricey side, my only gripe.

ebent

 

[tycreek]

I liked that idea too... was done by Ilia here: extremegreenmachine.

I'm in the middle of building lighting from Cree LEDs. I learned that while the LEDs are certainly bright to look at they don't provide usable light for riding at night without something to focus the beam. So I picked up a bag of small 9 degree reflectors for Cree LEDs, though it turned out that they were for a smaller size than the P7. Oh, well ... I made them big enough in the back and they work pretty good! The other reflector that I found for the P7s was 2x the size and 3x the degree of focus. I now have a bunch of extras if you need a few reflectors.

When my connectors arrive and I get time to mount them I'll post some pics of the lighting results. Here's my front and rear P7 LED lights ready for mounting.

The rear is a cheapo rear light that I gutted and mounted the LED inside.

Notes for my DC/DC converter 3.4v LEDs very HOT really fast, 3.3v still HOT and would probably be fine if moving, 3.2v no problem just warm... it took a trim resistor of 3.86k to get exactly 3.2v out the normal 3.3v output. The other way that worked is to put a 1 ohm resistor in series on the 3.3v out.

 

[Rifle]

http://www.hebeiltd.com.cn/?p=zz.led.resistor.calculator

Resistor calculator in case you go that route. I believe the P7 has a forward voltage of 3.5 ~ 3.8v and takes 2800 mA at most.

 

[Whiplash]

COOL Thanks! I think this will work out killer, and CHEAP!

 

[madact]

I just use an ultrafire C8 (P7 D-bin LED) on a bike-mount clip. Trust me, it lights up the road just fine (given the decent reflector it comes with in the C8, of course) - I tested it as a 'headlight' from behind the windshield on a road trip recently, 60kph in a car at night on windy hills / country roads, no problem. It throws a bit less light than car's low beams, but put two together and you have the measure of the cagers

 

[tycreek]

I sort of figured the idea here was to have lights small and still produce usable forward light... 2 P7's for about $15ea and a $15-20 DC/DC converter makes for a pretty good light that can be tucked out of the way easily. To be honest the MagicShine without battery is probably the "best" solution with Cree lighting on a bicycle for a few $ more but not as fun. Flashlights and Magicshine has a lot of aluminum heat sink around the LED and gets pretty warm if left on without movement. I have a 300lm cree flashlight and it gets uncomfortable to hold after awhile, unless it's cold of course!

I probably don't have everything optimal for OP's intentions... but what I'm working on is pretty close I thought.

The P7 specs do state 3.5v or 3.6v as the low side of input voltage depending on who you buy from and then there's some up around 12v. They were simply too hot for me at those voltages and I got control over the heat by lowering the voltage without a resistor ... I don't know if this will reduce the life, but I know the heat sure responded noticeably without needing a large W resistor. I tried 3.6v with AA batteries and they got drop it sizzle hot really fast! I went as low ohm resistor as I had and didn't find any sub 1 ohm resistors so I continued testing based on input voltage using the trim pins. Results gauged by how hot things got (not output light intensity). I'm not positive what LEDs I have but the measurements and looks fit P7 specs I've found to a T. Certainly YMMV... who knows really what you get sometimes!?

6W Night Pro BULLITe

Previously I posted a picture of my 2 LED headlight, here is the output when connected with 1 OHM resistor on a 3.3v output ... This is not how I'll be connecting them to the bike as I'll use the trim pins to achieve the 3.2 as I've bench tested. I don't have that DC/DC converter ready to leave the bench but the heat profile is the same as is light pattern in the short distances of a garage, so I expect my bike mounted results to be quite similar.

I'm not sure how far back the shed door is but I'd guess a good 80 something feet or so and can be seen with my LED lights. The fence is maybe 30ft from the camera and light. The light intensity does goes up some with a couple 1/10th of a volt increments but also produces considerably more heat.

With no lights other than that yard light way back there.

 

[Hyena]

running a plain LED like that without a reflector to focus is great for being seen but no good for actually seeing.
I have a single DX direct driven P7 torch mounted on my bike and it's good enough for riding in total darkness up to about 30-40km/hr. Above that and it gets a bit hairy

 

[Whiplash]

http://cgi.ebay.com/SSC-P7-D-1-mode-module-26-5mm-flashlight-/170506560322?cmd=ViewItem&pt=US_Flashlights&hash=item27b2fba342

Yeah I found this one, with the reflector, and the seller said it was self contained so I am going to get one and machine a nice shell for it out of aluminum. I think this could be a cool addition to my catalog if it works well, being as cheap as these are, I should be able to sell them for a fair price and still make a couple bucks..We will see how it works, but I figure a Lipo pack fully charged should light the heck out of one of these! I just love the size of it! Its less than an inch in diameter, only about 1.1" long and weighs practically nothing!I really like the size of it though as I am trying not to have really any obvious gadgets on the bike, I want as little "Pee-Wee Herman" as possible!

 

[Evoforce]

Magicshine 1400 lumin=16 watts great nightriding light. Has concentrated and wide angle tri-light and quick easy mount. Geoman.com (I think).

 

[Whiplash]

OK I will check into it! Thanks!

 

[fabiograssi]

Just trying to help:


this one I own, highly recommend:

http://www.dealextreme.com/details.dx/sku.25149

this, above mentioned:

http://www.dealextreme.com/details.dx/sku.36018

 

[Whiplash]

Thanks, I like the options! I ordered a single LED to try out, I plan on using a single Lipo or Nimh pack, most likely a 5000mAh, to power it as I don't want to eat into my main packs life, these things take 10 watts and over the course of a long ride, I think would use more than I would rather use up from my go power... Besides, battery space will not be at a premium in my prototype, I figure I will have plenty of room, even with 15AH @ 66.6V aboard!