I wanted to install LEDs for the interior lights of my truck to color-correct the yellow tungsten glow and to reduce the current drain during long periods of use. At autolumination.com I bought a white 9-LED festoon for the dome and a pair of red 4-LED festoons for the door markers. The dome light is reasonably bright, but I wanted to know how it compares to the incandescent it replaces. I used my Sekonic light meter to eliminate the guesswork. Here are the results. The readings were all taken in the dark with no other light sources but what was being measured. All readings were taken first at 0° on-axis at 30", and then at 45° off-axis at 30".

9-LED festoon: EV1.7, EV-0.7
Incandescent: EV1.6, EV0.7

For some perspective, some readings of other devices:
15-LED 3-D cell flashlight: EV5.3, EV1.1
1M candlepower 6vdc lantern: EV12.5, EV2.2
PrincetonTec "Aurora" headlamp (hi): EV5.2, EV-0.2
PrincetonTec "Aurora" headlamp (med): EV3.1, EV-1.5
PrincetonTec "Aurora" headlamp (lo): EV1.7, EV-2.5

For reference, a very bright cloudy day is around EV12. "EV" stands for "Exposure Value", a term used in photography to quantify scene brightness.

Conclusions? The 9-LED festoon is a 1:1 substitute for the 5-watt incandescent on-axis, and adequate but somewhat dimmer off-axis. If you want a lot of bright light in your cab, consider installing more than one, or using a different bulb with similar light output but wider dispersion.

As promised, edits to add pix.

The incandescent light:



Next, the new LED:


And for grins, the 1M candlepower lantern:


And finally, a backpack illuminated by the Aurora headlamp from around 5 feet:



Here's the Sekonic light meter. If any of you photo buffs are curious, PM me and I can tell you about it. In a nutshell, its incident and reflected metering is accurate from -3 to +18 EV +/- 1/3 EV. It's pretty impressive.

 

damn! very scientific-like!

 

Why not use a single luxeon from george?
http://taskled.com/install.html

 

I'd like to see test results from that

Erich

 

Luxeons get really hot.

 

Not georges.

 

Someone should bling out their 4Runner with blue LED's and whatnot on the floorboards I'd laugh pretty hard.

 

How are Georges any different than other luxeon "stars"? Does he have some sort of heatsink on them?

 

He uses pulse width modulation to control the heat and power consumption. Plus, they don't get that hot, it depends on how much power you put through them. If they can put them into a plastic flashlight, you can put them into a dome light.

 

if anyone has a luxeon they want me to test, send it on over. i'll post the results and send it back to you. otoh, how cool would one of these be? http://www.laminaceramics.com/products/bl3000.aspx

not very, given that the white engines are 26 or 28 watts.

btw sorry for the delay on the pix. i've been finishing up a number of honeydoos.

 

Sweet. Forgot about the PWM's... I like the luxeons and am thinking about buying one for each of my back up lights... since they don't really throw down any light anyway...

 

Steve... do you know if he's doing this with an analog circuit or using a PIC? I'd bet the cost would be about the same, and having a PIC driving one could be fun. Hmmm, there's the current draw issue though/

 

No, that's all beyond me. I can put them together with resisters and voltage regulators and that's about it. Even then, I don't understand it much.

 

Has anyone considered doing a dual light dome with LED's?

Like a set of white and a set of red. so you could pick which you wanted to turn on ...

 

i read something about a dual setup but haven't been too interested in pursuing it. a second switch would do the trick, with proper mounts.