Wattage of a White Ultra Bright 12vdc LED

It really depends on the LED and if it is an array or not.

Best to obtain a datasheet for the LED (or LED array) off the manufacturer's website.

Which one? The 10 watt one or the 6 watt one?

sorry could not resist.

The 10 watt LED is 10 watts @ 12 volts, and the 6 watt one is ..........

Are you saying . . . its on the description page?

Or on the specification page, I'm not sure anymore.

I am not from here either, so why would I know...?

Are you wanting to know the intensity of the LED? (Lumens)

Or; Are you wanting to know the power consumption of it? (Wattage)

The only way you can correctly answer the question is to locate and read the OEM specifications on the LED or contact the manufacturer.

Order of magnitude? The forward voltage drop multiplied by the current through it, oh, say 0.6V * 20mA. You do the numbers.

You're likely to lose a lot more through the current limiting resistor in series with it, I'd say.

Did you bother to look at the data sheet or telephone the manufacturer before coming here? No? I thought not.

I don't have any specifics, but I believe I have seen that certain white LEDs are used in museums, due to the fact(?) that they emit essentially no UV, so don't damage paper, textiles, etc. Any comments?

I stand corrected. The earlier white LEDs emitted some UV. I think most now are a blue LED with a yellow phosphor resulting in a white light output.

But are they not less of a fire hazard, due to less watts (heat) also? What happens when LED burns out?

(Less heat) Absolutely!

(burns out) That could depend on the design of the power supply. My experience is that LEDs always fail to an open, not to a short as some other diodes are known to do. Of course that could be because the current-limiting resistor will quickly burn out (_nearly always to an open circuit) if the diode shorts, at least in simple designs.

I agree.

I posted similarly, after you time wise, but before I read your post.

In my experience only, I can honestly say that I have never personally seen a LED burn up as you describe/think.

It seems that they simply "burnout" and just stop working.....Also, they do not seem to have the habit of some filament bulbs to go to a "BAD" short circuit in their final death throes....either! Seen that MANY times, it usually drops the breaker and makes a loud noise. Some designs appear to be affected more than others...

You must have seen older LED displays, with Pixels missing, but otherwise still working.....replace jut the LED and it works again....

This may even be at least partly due to the series resistor often included (or as part of the LED nowadays), keeping current at a safe value....but I am not an expert on the finer points of LEDs either, so that was just a guess...someone here will know better I am sure.

I am sure sometime, somewhere a LED has caused a fire, but in comparison with normal filament bulbs they are millions of times safer and use far less power too.....

Naturally, I am NOT talking about laser LEDs and their high heat outputs, but when working only, as they also seem to die a "quiet" death too!!

I hope this helps.

2-30 watts...give or take

Technically seen, there are no 12 volt LEDs.

The ones marked as such have extra circuitry to drop the voltage to a proper value for the colour and power of the LED in question.

I hope this alerts you to a possible thinking error.....

Right!

Joe6310 - See post #6 for the voltages (at the knee of each curve), as a starting point. Of course you will need to know the actual voltage and current of the specific LED you choose, at the brightness level you choose. In case it is not obvious, increasing the brightness will shorten the life expectancy of the LED.

You mention strings of LEDs. If it is a series string, you only need one appropriate current limiter for each set of series LEDs (assuming that all LEDs in the string are identical).

Measurements are ALWAYS more accurate than specs.

1) put an ammeter in series with the LED, read the current.

2) put a voltmeter across the LED, read the voltage.

3) multiply amps * volts = watts consumed by LED.

If you need to know the watts consumed by the whole LED + dropping resistor circuit, multiply the previously measured current by the supply voltage.

"Measurements are ALWAYS more accurate than specs.

Change "accurate" to "useful", and I totally agree.

"Accurate" has implications of correctness. If the measuring instrument is not correctly calibrated, is used with an inappropriate scale, or is simply defective, the measurement will not be accurate.

Even an inaccurate measurement can be useful (for example showing that the device is connected backwards), although obviously an accurate one is more useful.

Your directions are indeed correct, when followed by someone with at least a little knowledge of electrical devices.

dkwarner:

Correct! Specs are fine for design. Measurements of actual circuits are more useful to tell us what is actually going on. And ACCURATE measurements are the most USEFUL of all.

Your other point taken as well - connecting the meter backwards won't tell us much.

With LED's you need to pay attention to the LUMENS rating, as well as the watts. Watts are actually a measure of power consumption, not luminance. A much more efficient light will blind you with much less power consumed.

Come back joe6310! Sounds like a song title. Do want to know the wattage so that you can;

1. make a guess as to how bright it may be

2. work out how many LEDs your power supply can support

3. take a guess at how much heat will build up in the enclosure

4. compare with existing non LED lighting

Answer these questions and you will get the knowledge you seek from the guru.