Mountain Bike Reviews Forum banner

1 - 18 of 18 Posts

·
maker of trail
Joined
·
2,008 Posts
Discussion Starter #1
I did a lot of reading here about DIY lights, learned a fair bit... So I figure I would share my little lights....

I went a different route though, due to cost etc, plus I wanted to try something different.

Using 60 X 40kmcd led's per pannel, uses a current control boost driver with battery management from a micro, runs from 4.8V 4.6Ah NiMH pack, run time is about 3.5hrs at full power. Brighter than a 20W halogen and totally kills a 3W led flash light a mate of mine has (might not be the latest gen LED though). My estimates put the light output between 300 and 500 lumen.

Total LED power is about 4.4W.

1) The first test to see if I wasting my time
2) Blank PCB
3) LED pannel
4) Driver
5) Partially completed light
 

Attachments

·
maker of trail
Joined
·
2,008 Posts
Discussion Starter #4
I will post up some beam shots, they are 20deg leds, so its fairly wide, took them out for a spin the other night (two panels mounted to my handle bars) and they light up a trail pretty well, but its hard to compare since they are the only lights I have.

Is there some sort of "standard" setting for a camera so you can compare with other lights online? I would assume a given shutter/aperture/ISO would (should) yield comparable results for different cameras??
 

·
Registered
Joined
·
914 Posts
when I posted my beam shots i posted my camera settings but its going to vary on outside light also. But should be a good start. Alot of people use point and shoot camera's so the camera auto adjust to the light and it usually doesn't give thier beam shots justice. Another thing i did was i put a known light in my beam shots so people could compare it to. I used my dad's NR HID light and used the same settings. You said you didn't have anyother lights so you might want to use a well known flash light like a mag light so we know how bright those are.

I am very curious on how well this works. I have seen flash lights that use alot of LED's like that but the beam patterns were not very good from what i could see. But they didn't have 60 of them either. Looks good, take pics with it on your bike so we can see what it looks like too.
 

·
maker of trail
Joined
·
2,008 Posts
Discussion Starter #6
brent878 said:
Looks good, take pics with it on your bike so we can see what it looks like too.
The first one I'm running is a bit of a hack job to test the driver/software etc so its rough as guts :p

So I'll post some up when I get something a little more neat looking... :)

Beam shots I can do though... later when I get home...

Brightness comparisons may not be the greatest since we have a fairly decent snow covering...
 

·
Registered
Joined
·
346 Posts
The best tool for beam comparisons is to give us a standard to compare it to. If your camera is on the same exposure on two pictures with two different lights aimed at the same point, with say, one shot with a 10w halogen spot and the other of your new lights, that is the most useful to me. Just tell us which is which so we have a baseline. Beam shots that just show a flood of light against a wall are almost worthless if there's no comparison with objects at varying distances.

Overall, nice project. I'll be interested to see the results. It's certainly efficient and cost effective.
 

·
maker of trail
Joined
·
2,008 Posts
Discussion Starter #8
rockymtnway said:
The best tool for beam comparisons is to give us a standard to compare it to. If your camera is on the same exposure on two pictures with two different lights aimed at the same point, with say, one shot with a 10w halogen spot and the other of your new lights, that is the most useful to me. Just tell us which is which so we have a baseline. Beam shots that just show a flood of light against a wall are almost worthless if there's no comparison with objects at varying distances.

Overall, nice project. I'll be interested to see the results. It's certainly efficient and cost effective.
Yeah I want to do a comparison with a buddy who has 15W halogens.

I was thinking if "we" could come up with a standard setting for cameras to capture beam shots (since the measurements for cams are pretty standardized) that would be great, then you could roughly compare them with people over the interwebz.

Obviously it wouldn't be hugely accurate, but still would give people an idea.
 

·
Registered
Joined
·
346 Posts
I've had luck with F2.8 @ 1 second, but most new point and shoots won't do that.
 

·
maker of trail
Joined
·
2,008 Posts
Discussion Starter #10
Finally got around to some test shots... sadly only against a garage door, it will give an idea of the beam though.

Used the same camera settings as teh led shoot out posted before
F4 @ 2sec, ISO200, 16mm lens

1) Ambient
2) Limp home power
3) One pannel
4) Two pannels
5) Mini mag lite (AA size sorry only light I had lol)
 

Attachments

·
maker of trail
Joined
·
2,008 Posts
Discussion Starter #12
msxtr said:
Wowwwwwww, I'm very, very impressed. I don't undertand how with "normal" leds give so much light...:eekster: :eekster:

Greetings - Saludos

msxtr
The newer white LEDs are actually very efficient some reaching almost 70Lumens per W, you just need lots of them :)
 

·
Registered
Joined
·
346 Posts
Thanks for the pics. I have the gears churning now. How are they for temperature? How warm do they get?
 

·
maker of trail
Joined
·
2,008 Posts
Discussion Starter #15
rockymtnway said:
Thanks for the pics. I have the gears churning now. How are they for temperature? How warm do they get?
They would get quite warm, just the leds on the PCB, no cooling at 25mA per led hit just under 90degC (way too hot!).

The intention is too cool through the back of the PCB, thats the way I laid it out, you have about 3sq in of area to couple through.

With the LED's mounted on the aluminum as above, they don't get warm at all when there is a small amount of air moving (ie riding). They do still run quite warm when stationary at the moment I would need to add fins to the back to prevent that.

I throttled the panels back to 20mA per LED, due to concerns over thermals.

Once I have built better enclosures, and built the thermal limiting into the software I'll push them back to 25mA, where they make quite a bit more light.

I have lots of spare PCB's so I'll play around when the next order of LED's arrive :)

ps

Merry xmas to all who celebrate it :D
 

·
Registered
Joined
·
346 Posts
Cool. What's the diameter of each LED? And/or, how many LEDs could you fit into 7/8" square? I was thinking about a box tubing solution somehow, either drilling holes in it for the LEDs to peek out, or going in the end of 2 pieces (Achesalot-type solution). Still, cooling is going to be an issue one way or the other, just like the high power units... Guess there's no way around the physics of transforming one form of energy to another...
 

·
maker of trail
Joined
·
2,008 Posts
Discussion Starter #17
They are 5mm LED's.

I'm not sure your reasoning for cutting individual holes for each LED, the heat comes out of the leads not through the plastic lens, hence cooling through the back of the PCB...

in my mind cooling is not an issue..

Anyways... out for Xmas... :)
 
1 - 18 of 18 Posts
Top