How bright is a Lumen...or how many do I need?

[Stinky]

At the autoparts stores and I notice that they are selling LED driving lights.

I look at them and notice that they start at about 5,000 Lumens and that a light bar (say...2' across) is 20,000 Lumens. I have a flashlight that has 1,000 Lumens. So, when I see the above 5,000 Lumen light, I think...Welcome to Fruita (WTF), that ain't worth having.

Back in the day...I knew that a headlight was ABOUT 55 watts and a light that had 100,000 candlepower was just a bit brighter. 100 watts was real bright and made a huge dif. A KC Daylighter is/was 385 watts.

So, how bright, in Lumens of a light do I need to make a dif? This would be on a buggy and/or off-road application...or maybe on a deserted 2-lane when I might want to drive 80

 

[Russell]

LED lights are often way over-rated in their lumen output. I'd take their advertised number and cut it in half for actual useful light output. 5000 lumen LED would barely be adequate for driving at 55mph.

 

[Blue85]

Interested in the math, I found this table.

Light type Typical luminous efficacy (lumens/watt)
Tungsten incandescent light bulb 12.5-17.5 lm/W
Halogen lamp 16-24 lm/W
Fluorescent lamp 45-75 lm/W
LED lamp 30-90 lm/W
Metal halide lamp 75-100 lm/W
High pressure sodium vapor lamp 85-150 lm/W
Low pressure sodium vapor lamp 100-200 lm/W
Mercury vapor lamp 35-65 lm/W

So an old 55W sealed beam should be like 1100 lumens. The KC 385W should be over 7000.

I think LED manufacturers lie about lumens kind of like audio amps and oil-less air compressors get very strange power measurements to get bigger numbers. I would have suggested that power consumption gives an idea of LED light output, but the table above allows a factor of 3 . Perhaps that's across everything from key-chain LEDs to light-houses and within a given range (i.e. lightbars) there isn't much variation. Would be interested to see some data.

Also interesting to note that sodium lights are still more efficient than LED. Wonder if those numbers include the ballast.

 

[6872xtc]

Good info @Blue85 !
I will say that I have a set Rigid Industries D2 lights on my Jimmy and they are a ton better than the factory sealed beam headlights were.
(It has the mini-quad lights)
I changed the sealed beams out for E-code housings and have the 55W bulbs. I also made all 4 come on with the high beams, and now they are brighter on high than the Rigid lights, but not on low.
The D2 is rated at 3K lumens each.
I know that lots of people don't believe there is a difference in LED stuff, but I personally disagree. However I agree that some of it is overpriced.
I would recommend going to Rockstar Customs and talk with them. They have different brands to look at.