Reply to post: Re: @Scatter - look at the numbers, not the technology

White LED lies: It's great, but Nobel physics prize-winning great?

Richard 12 Silver badge
Boffin

Re: @Scatter - look at the numbers, not the technology

Seeing as you insist - two 230V products you can buy now:

Coemar LEDko @ 26deg: under 9 lumens/Watt. (Source: LSI, ignoring power factor losses.)

ETC Source Four (750W Halogen) @ 26deg: 13 lumens/Watt. (The 375W lamp is about 11 lumens/Watt.)

- In reality the LEDko is worse due to power factor which again acts in the halogen's favour.

There are several worse LED fixtures, this is simply the first one I found with published figures that you can check. I've seen LED fixtures that barely reach 5 lumens/watt due to poor optics, diode overheating and (especially) power supply efficiency.

They're generally easy to spot - if it doesn't give both input power and field/beam lumens, it's probably terrible. (Converting lux to to lumens will overestimate as datasheets give peak lux, not average)

Quite a few domestic ones are really terrible, primarily due to cutting too many corners in the LED driver/power supply design. Aside from that, the optics need to match the purpose - I've seen a lot where the optics are so narrow that you can't even use it as a reading light, yet it's sold as room lighting.

That's before you even start considering the quality of the light - the CRI and CQS of most domestic LED are painfully low, even worse than cheap florry.

They can be good, but most aren't and some are truly terrible.

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