The reality of LED wattage....?


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Sorry if this has been discussed before.

I'm no electrician automotive or otherwise but I was looking around fleabay for a couple of spot/pencil beam lights. And after looking at several and reading feedback (as you should) I am slightly confussed.

If an LED light consists of 7 leds fashioned into something that resembles a circle and the seller claims 70w that to me would indicate that each led was rated at 10w......correct? Therefore, in my limited understanding, the output of this device would be 10w as it is actually 7 individual leds of 10w. I don't believe that they can be added together to give a claimed output of 70w......correct? So when another seller claims 3600w that to me is just ludicrous! I don't believe that the average automotive electical system could cope with that much current I said I'm no expert.

Just would like it explained in simple terms, trying to get my head around this.
It used to be easy years ago, you bought halogen and it came to bulb wattage and who had the best reflector/lens. Ah the simple days....


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Watts are watts. So 7 x 10 is 70w. I’d say that the second seller is probably claiming 3600 lumens. I love the translation in some of those adds

Buuuuut on cheep ebay lights I would not be completely sure that you will get what you think you are paying for in LED quality. But you are probably getting what you paid for if that makes sense. I run China ebay lights. Simply because I don’t think you will get 10x the performance for 10 times the price. The biggest downside of cheep lights is cheep mounts. I am heading to the cape and will remove my cheep lights for this reason. On the beach / road they have worked perfectly for the last 4 years. What I would like is a reasonable priced good quality light at a reasonable price.


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LED wattage seems to mostly be what they feel like labelling it

So many even contradict themselves in there own ads eg 300w Led light bar and then in specs 10amps at 12v which = 120w

If you buy cheap its a lottery, best going with word of mouth recommendations if going that path.


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......... I run China ebay lights. Simply because I don’t think you will get 10x the performance for 10 times the price. ......
Yes, I'm of the same opinion, can't justify $1200 for one light doesn't matter what three letter brand you put on it. Just had a re-read of one of those adds, definately claiming 3600w from 300 chips that's 12w per chip and 360000 lumens, 52in lightbar, apparently.:rolleyes: So if google is correct and amps = watts/volts that would make this 3600/12.8 = 281.25a, well my alternator only puts out 120a anyone running a 300a alternator. Which is why I question the 7x10=70, I just think that it is 7 x the brightness because there are 7 chips not 7 x the output. I'm still confussed.


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Ok I'm looking at it this way now.

If I had 2 halogen driving lights of 100w each I would have 2 x 100w but not 200w. Because they are individual, seperate from each other. If I took 7 of these and arranged them in to a circular array then there would be 7 individual lights of 100w each but not 700w, however, the illumination would be concentrated together. Would a single light with a 700w globe give the same illumination?

Now i'm really confussed.


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Don’t try and compare power usage and light output it’s apples and oranges. Wattage is a measure of power and is constant across voltages. You simply add wattage together and get a total.

Light output will vary quite a bit based on the efficacy of the diode. From a quick google in the last few years they have gone from 60 lumens per watt to 100 lumens per watt. But again I doubt that the China lights will have anything close to the highest efficacy of the nicest leds. LED’s still convert a percentage of that power to heat so unless you know how efficant they are it’s hard to tell.

Then comes optic design of the reflectors and lenses and how effective they project that light. The light bar on my roof is terrible at throwing light over distance. But they turn 50 meters in front of the car into daytime.

So I suppose the moral of the story here is just buy the one that has the strongest looking mounts that fits your application and give them a go. If it doesn’t do what you want put them on gumtree and try again.

Aaron Schubert

Don't believe a lot of what the sellers claim on eBay. Often the maths does not add up, and if it does, its likely not advertised correctly anyway. This is only referring to the cheap, non brand name products sold in mass.



Active Member
led bulbs as in light bars are not constantly powered, they flash on and off by the electronics attached.this is because they over power them past the sustainable voltage to get max brightness. Without pulsing you either need to reduce voltage (less bright) or blow the led due to excess heat.

so our eBay seller ( I will make up numbers for example ) sells a light bar with "7 x 10w led lights" let's also say the led on its own is 12volts peak voltage and maybe 6volt constant.
Really he selling a 10w led that he pulses 12v on and off equally so therefore it consumes 5w. But as a smart seller he doesnt lie because they are 10w, but he isnt really giving you the factual either. Hence the strange current (amps) draw not matching the stated wattage.
there are so many combinations of making, rating and claiming the average punter will have no idea.
to make a technical evaluation you would need manufacturers spec of the led. There are a few from memory like osram and Phillips in various spec. that most light bars/spotties use. Next you need the specs of the electronics control. From there you came make a real assessment. Good luck with that . I just look at the basics, word of mouth and price


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Yes. You beat me. Nearly all the LED's I've measured consume about 1/2 the stated wattage. If you look at the specs for LED's you will see they also have different grades/quality for the same type. The Ebay sellers seem to rate them according to the top model at 100% duty. About 40% of the rated lumen output is probably realistic.


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There you go I was aware that the pricey lights used fast switching but I always thought that was probably beyond the scope of a $30 light. I will measure my cheapies and see what they use.


I dont really understand any of the volt, amp,watts sorcery of the electrical world , be it automotive or otherwise, and dont really care to if im honest. I just look at lumens in an add.

If a set of spotties or lightbar claim to be above say 15000 lumens i figure it must be reasonably bright, and if around $150 if it last a couple of years then im satisfied with that.

I run a single row 50" lightbar on the roofrack which is claimed to be around 13000 lumens, is it, i dunno but its good for around 300mtrs of good light turning night into day which im happy with and being independently switched its great for night runs as i can just have my parkers on for taillights and only the lightbar on out front. I have 0 care factor about what power it draws and never had an issue in the nearly 3 yrs iv had it.

As stated above the mounts are of biggest concern for me and sofar their holding well, but the lightbar will be coming off for this yrs cape trip as i think long distance corrigations may just kill it.

Not really any answer to your questions about power so apologise if this post is irrelevant.


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I don't know all the ins and outs but what I do know is that if someone spends $1000 on a set of lights and you see them in action they light up everything and are blinding to drive into. On the other hand I have seen cheap lights that are the same watts, lumens and whatever that are not much better than a candle...
but they are cheap and they look very cool on the front of a 4by;)


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Some of the cheapies are quite good and excellent value for money, the trick is to try and work out which are the good ones amongst the rubbish
The advertised lumen output is also misleading as it depends where they take the reading from, I don’t know if there is meant to be a standard method of measurement for that?


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Iv`e been caught by the advertised output of a set of LED driving lights. Said to have 360 (36 x 10 watt led`s) watts per light but when put on the meter were in reality only 120 watts @ a 10 amp draw with 12.5 volts. When you read the specs it said they could be run at up to 36 volts - hence the claimed 360 watts but who in reality runs a 36 volt system.

The measure of distance that light travels is measured in LUX - 1 lux is the ability to read a newspaper at 100 meters & would be a better way to judge how good a light is. Some brands do have a lux rating but most of the cheaper brands do not.


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I bought a cheapie light bar thats mounted on my bull bar , lights up the road very well , I've had it 5-6 years and no problem .
Another question you should ask your self is much night driving are you intending to do ?.
I dont do very much night driving at all , so opted for the cheapies .


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Have you had a look at the Jaycar lights ?
If you do a little research there getting some good feedback for a reasonably priced light.

The other cheap lights that are getting some positive feedback are the 4wdsupercetre
LED driving lights.
If you can pick them up in store, might be worth it.


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Another question you should ask your self is much night driving are you intending to do ?.
I dont do very much night driving at all , so opted for the cheapies .
I do lots , and Bosses being Bosses will always buy something big , but is cheap ;)
Id kill for a decent set of HID spots but have to put up with this piece of crap , I wouldn't put it on Jean's Mazda 3 for any lighting advantage.


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Thank you everyone for all the input I have a better understanding of what I'm looking at now.

The search continues.