Candellas? / Lumens? / Candle Power?

[nashville_bill]

I'm thinking about making an LED panel to replace my tail/brake light bulbs. I have found specifications for LEDs rated in mcd (microcandellas?) and incandesent 1157s rated in Lumens. I am trying to find out how these brightness measurements compare. Can anyone help me with this?

[btdtdan]

Hi Bill,
I suppose you read TC fix on LED coversion but just in case you haven't:

Running lights drew total 3 amps. Brakes drew total of 9 amps, and that got added to the 3 amps running lights at same time when applying brakes. Then add 2(two) 1156 turn signals at 4.5 amps per side if I was signaling a turn while stopped for a total surge draw of 16.5 amps!

With LED's for brakes and turn signals: 0.06 amps total running lights; 0.60 amps total brake lights; and 0.06 amps total turn signal surge for grand total of 0.72 amps, a power savings of ~15.78 amps!

He doesn't talk about lumens but the amps clear up the pwr drainage business but I bet he can tell you how bright they are and the difference. I just read and try to learn from all you guys with experience. Someday I might even actually contribute
Dan

[xssiveone]

Bill, in additon to TC's solution, here is another one that uses readily available truck tail/brake lights.. LED conversion

[randy]

Here's yet another:

SuperBrightLED's.com

Randy

[nashville_bill]

I've been to several LED web sites and found what look like great LEDs to use, but I would like to know how much light a standard 1157 emits so I can make an informed decision on how many LEDs I will need to install to equal the original bulb. The current draw, in amps, can't be used to compare the two because LEDs use so much less than the incandescent bulbs.

[skids]

Illuminance or Illumination, E, is a measure of luminous flux per incident area. Typical units are "lux" which is lumins per square meter, or "foot-candle" which is lumins per square foot. I know you can get some conversion factor for square meter to square foot to get some idea of the differences of the units, BUT, the illumination drops as the square of the distance. Also, bear in mind that LEDs are directional in nature. You will definately depend on your lens to scatter the light so that people can see it from angles. If you make your own with a circuit board, you will probably want to shin a couple towards your licence plate to stay out of legal trouble (standard xs11s).

Originally posted by nashville_bill
I've been to several LED web sites and found what look like great LEDs to use, but I would like to know how much light a standard 1157 emits so I can make an informed decision on how many LEDs I will need to install to equal the original bulb. The current draw, in amps, can't be used to compare the two because LEDs use so much less than the incandescent bulbs.