How many watts / amps for LED light bar?

[LD1]

To understand a LED you really have to dive into the specs.

Not sure if it holds true on 12v stuff.....but alot of times your household LED's are rated in watts is because they can be operated over a pretty wide voltage range.

IE: a 100w LED might have a voltage range of 100-277v. So depending on the supply voltage, the amperage will be different.

100w at 100v would be 1 amp. But if you fed the SAME light with 277v.....you will get the SAME 100w light output, but at only ~1/3A

Someone mentioned above a 100w that draws 7.33a. Well conventional wisdom says putting that on a 12v tractor.....100w/12v should draw 8.33A....

Well.....what 12v system actually operates at 12v? None right. They are 13.5-14v or so with the alternator charging.

So comparing amps on a LED is not really as accurate as watts. You just have to make sure you are comparing actual wattage of the light, and not "equivalent" wattage....

 

[WranglerX]

Maybe this site will help unravel watts vs lumens vs amperage draw ("watts")...

Lumens to Watts Conversion Chart: Choose the Right LED Bulb

The old days of selecting light bulbs by wattage are over. Use our lumens to watts conversion chart to choose the right LED bulb every time.

www.voltlighting.com

 

[Williy]

For me take a 55 watt 12 volt bulb in its
place you can use an led 12 volt and any
watts from 5 to 55 watts but I do believe
that a 35 watt 12 volt led would be more than
sufficient to replace the 55 watt 12 volt bulb
LED's are a blind mans friend brilliant

willy

 

[jyoutz]

I just wired my LED lights directly to the battery with a switch and relay. Then I used the work light wiring to install a USB charger for my phone.

 

[jigs_n_fixtures]

couple of notes of lessons learned when I putLED lighting on my tiny truck.

The Watt rating for the lights I installed was way off. I actually bought a clamp on ammeter which can measure DC Amps to be sure the wiring I ran was large enough. They pulled half the amps they should if they were really burning the number of Watts they stated.

You always allow a 10 to 15% safety factor when you Calc the Amps to size wire and fuses/breakers. So, I divide by 10, 100, or 200. Which automatically leave a 20% safety factor. And can easily be done in your head.

LEDs generally produce 100-lumens per Watt.

Even though the lights only draw half the Amps I thought they would, I’m glad I upsized the alternator from 35 to 90-Amps. Because If I plow at night with all the lights on, and hit the button to change the plow settings, the engine lugs down from the load.

 

[DaBear3428]

modern leds are at about 120 - 140 lumens per watt.
50 watts would give you a metric crap ton of light for less than 5 amps on 12 volt system.

 

[DaBear3428]

couple of notes of lessons learned when I putLED lighting on my tiny truck.

The Watt rating for the lights I installed was way off. I actually bought a clamp on ammeter which can measure DC Amps to be sure the wiring I ran was large enough. They pulled half the amps they should if they were really burning the number of Watts they stated.

You always allow a 10 to 15% safety factor when you Calc the Amps to size wire and fuses/breakers. So, I divide by 10, 100, or 200. Which automatically leave a 20% safety factor. And can easily be done in your head.

LEDs generally produce 100-lumens per Watt.

Even though the lights only draw half the Amps I thought they would, I’m glad I upsized the alternator from 35 to 90-Amps. Because If I plow at night with all the lights on, and hit the button to change the plow settings, the engine lugs down from the load.

researched my reply and it is incorrect

 

[DaBear3428]

A sort of yes, here.... A lot of LED come in different color temperatures expressed in kelvin and I believe 5500/6000 k. is equivalent to sunlight... Anything with larger number tend to be into the bright blue spectrum, where lesser numbers tend to be on the softer brown tones.... The brighter blue spectrum as actually harder on the eyes than the softer shades of brown...

close 4100K is close to sunlight

 

[LD1]

close 4100K is close to sunlight

Depends on the time of day.

But everything I have ever read puts the sun closer to the 6000k range. And for comparative purposes when it comes to LED's....most say the 5000k bulbs are "daylight"

 

[swines]

The original definition of daylight color temperature was for color film and it is 5500 degrees, Kelvin (K). Tungsten (artificial light) balanced film color temperature is 3200 degrees Kelvin. The original definition of the daylight color temperature was made by the National Bureau of Standards by measuring daylight in Washington, DC on the summer solstice at noon (lucky for them it wasn't cloudy). I would have to look up the actual year in one of my reference books. This was done so that color rendition was standardized and consumers would have the same color rendition by the film regardless of the manufacturer. The 3200 degrees Kelvin for tungsten-balanced film was determined through testing of incandescent lights and finding the combination of light output versus lamp longevity. The higher the output, the "bluer" and closer to daylight, but the shorter the lamp life. As an example, a 2900 K tungsten lamp has an expected life of 1,000 hours while a 3200 K photo lamp has an expected life of about 12 hours.

Today, with digital cameras, it doesn't matter because the cameras or phones will automatically white balance to whatever color temperature light is illuminating the subject to be photographed.

For LED lighting, this means that LEDs with a "lower" color temperature (3000 K and under) will look like an incandescent light bulb with a warm color rendition while those with color temperatures above 4000 K will be bluer and closer to daylight. Most people like LEDs with a lower color temperature for indoor lighting in living spaces as the light is warmer and mimics the look of light bulbs. For vehicle lighting, most of the LEDs are 4000 K and higher and closer to daylight giving a look, that to human eyes, seems "brighter."

This has somewhat to do with the spectral response characteristics of human eyes and the Purkinje Effect and the shift from photopic vision to scotopic vision, or the color sensitivity of eyes shifting towards blue under low light conditions. What this means is a greater sensitivity to contrast differences. Human evolution for seeing better at night under moonlight.