Author Topic: I thought LED lights were efficient?  (Read 9078 times)

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Offline james_s

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Re: I thought LED lights were efficient?
« Reply #50 on: April 08, 2022, 07:51:33 pm »
If you buy quality bulbs they are pretty reliable. I have lots of LED bulbs that are >10 years old, the one in the porch light by my front door was installed in 2011, runs dusk till dawn and still looks like new. I have a bunch of Philips Hue bulbs too, both white and RGB varieties and I've yet to have one of those fail.
 
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Offline NorthyTopic starter

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Re: I thought LED lights were efficient?
« Reply #51 on: April 08, 2022, 08:42:47 pm »
I've ordered a couple of the V-Tak 40W LED battens today, when they come I'll see if they'll open up easily to see how they are driven. I've seen Big Clive on YouTube turning down LED bulbs to greatly improve their life.

Thanks,

G
 

Offline cdev

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Re: I thought LED lights were efficient?
« Reply #52 on: April 09, 2022, 12:37:10 am »
If you buy quality bulbs they are pretty reliable. I have lots of LED bulbs that are >10 years old, the one in the porch light by my front door was installed in 2011, runs dusk till dawn and still looks like new. I have a bunch of Philips Hue bulbs too, both white and RGB varieties and I've yet to have one of those fail.


How do they do in cold weather. When its cold, it seems some LED lamps struggle to stay lit. CFLS are even worse.

I've never read about this.
"What the large print giveth, the small print taketh away."
 

Offline james_s

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Re: I thought LED lights were efficient?
« Reply #53 on: April 09, 2022, 09:49:06 pm »
How do they do in cold weather. When its cold, it seems some LED lamps struggle to stay lit. CFLS are even worse.

I've never read about this.

LEDs love the cold, I've never heard of one having trouble in cold weather. Certainly none of mine have ever caused me problems, the coldest I've ever seen it get here since installing the LEDs was about 12F and they were perfectly fine in that.
 

Offline PushUp

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Re: I thought LED lights were efficient?
« Reply #54 on: April 09, 2022, 10:17:12 pm »
Just as an add-on to a message I wrote - this is my main equipment, together with a small saw not in the picture:






As for checking/repairing a dead SMD LED, you immediately spot the black dot:






My HMC8012 and Gossen Metrawatt do use > 6V in diode mode, so that I am able to test each SMD LED. Of course I don't see the voltage drop, but the DMM is able to light up any SMD LED, which neither my Fluke 289, nor my Keysight U1273A is able to do so.






If you wanna have it a bit easier, you may wanna invest in a ZEN50 from Atlas Peak, which shows the voltage drop of around 7.2V at 2mA or a little bit more at 10mA and so on.

You can shorten this procedure with the ZEN50, when only testing the (most likely) one dead SMD LED and all other start flickering immediately, so that you know, that you are on the right track!






That's it. Cheers!   :)
 

Offline Siwastaja

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Re: I thought LED lights were efficient?
« Reply #55 on: April 10, 2022, 07:50:52 am »
Any even remotely decently designed LED bulb works at however low temperature just fine.

Misdesigned crap can fail to work due to any "external" reason. The real reason is failure in engineering, deliberate or not. In other words, there is no actual real engineering reason why LED lights should fail to operate at low temperatures. Fluorescent lamps are different, they really need to maintain high temperature inside the tube, as evidenced by the warm-up times even in room temperatures. LEDs work only better, the lower the temperature. Increasing ESR of electrolytic capacitors at low temperatures is the only "problem" I can think of, but it should not be a show-stopper. Cheap crap often even does not use them (evidenced by flicker).

Some manufacturers take advantage of the reputation of crap products failing at low temperatures, selling "special" low temperature LED bulbs. I would not buy them, and just try to find normal products with decent reputation, and if they fail to work as they should, return to seller and claim for money back.
« Last Edit: April 10, 2022, 07:52:48 am by Siwastaja »
 
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Offline madires

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Re: I thought LED lights were efficient?
« Reply #56 on: April 10, 2022, 10:30:58 am »
How do they do in cold weather. When its cold, it seems some LED lamps struggle to stay lit. CFLS are even worse.

LEDs in the garage work just fine. Even in the fridge.
 

Offline BrokenYugo

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Re: I thought LED lights were efficient?
« Reply #57 on: April 10, 2022, 06:56:13 pm »
If you buy quality bulbs they are pretty reliable. I have lots of LED bulbs that are >10 years old, the one in the porch light by my front door was installed in 2011, runs dusk till dawn and still looks like new. I have a bunch of Philips Hue bulbs too, both white and RGB varieties and I've yet to have one of those fail.


How do they do in cold weather. When its cold, it seems some LED lamps struggle to stay lit. CFLS are even worse.

I've never read about this.

I would assume cracked solder joints or something to that effect. LEDs can handle a lot more than earthly cold and the driver parts are all good for it, if you go on youtube you can find demonstrations where they dunk a regular non phosphor 5mm LED into a small container of LN2, which is cold enough it screws with the semiconductor physics and changes the color of the output dramatically.
« Last Edit: April 10, 2022, 07:00:04 pm by BrokenYugo »
 

Offline cdev

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Re: I thought LED lights were efficient?
« Reply #58 on: April 12, 2022, 03:18:47 pm »
Thanks for that pointer. This is very interesting to see and know.





his is an RF-excited lamp..



Look at the related videos for more..
"What the large print giveth, the small print taketh away."
 

Offline NorthyTopic starter

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Re: I thought LED lights were efficient?
« Reply #59 on: April 13, 2022, 05:28:42 pm »
The lights were delivered and they are the wrong brand  |O

Graham
 

Offline wraper

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Re: I thought LED lights were efficient?
« Reply #60 on: April 13, 2022, 05:36:44 pm »
What did you actually receive? Not necessarily they are any worse.
 

Offline NorthyTopic starter

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Re: I thought LED lights were efficient?
« Reply #61 on: April 14, 2022, 09:55:45 am »
They have sent LEDBRITE units, not the V-Tac ones.
On the specs (which I know can be massaged) these ones are 100W/lm and the V-Tac are 120W/lm.
I think I'd rather have the V-Tac just due to them being a 'bigger' brand.

G
 

Offline NorthyTopic starter

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Re: I thought LED lights were efficient?
« Reply #62 on: May 26, 2022, 09:16:29 pm »
A little update. I finally got them sent back and a refund.

I've just ordered two more of the V-Tacs, lets see what turns up next week  :-//

G
 

Offline TimFox

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Re: I thought LED lights were efficient?
« Reply #63 on: May 26, 2022, 09:42:20 pm »
I assume you mean lm/W, not W/lm.
 

Online DavidAlfa

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Re: I thought LED lights were efficient?
« Reply #64 on: May 26, 2022, 11:10:33 pm »
Then there's this, with Z+++ energy rating and 100W per lumen :D

Hantek DSO2x1x            Drive        FAQ          DON'T BUY HANTEK! (Aka HALF-MADE)
Stm32 Soldering FW      Forum      Github      Donate
 
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Offline TimFox

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Re: I thought LED lights were efficient?
« Reply #65 on: May 26, 2022, 11:11:34 pm »
I never watch the videos.  How many lm/W can be extracted from the arc?
 

Offline BrokenYugo

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Re: I thought LED lights were efficient?
« Reply #66 on: May 26, 2022, 11:57:08 pm »
A quick google indicates something like 4 to 9 lumens/watt for carbon arc.
 

Online Zero999

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Re: I thought LED lights were efficient?
« Reply #67 on: May 27, 2022, 08:39:39 am »
How do they do in cold weather. When its cold, it seems some LED lamps struggle to stay lit. CFLS are even worse.

I've never read about this.

LEDs love the cold, I've never heard of one having trouble in cold weather. Certainly none of mine have ever caused me problems, the coldest I've ever seen it get here since installing the LEDs was about 12F and they were perfectly fine in that.
If that's the coldest it's been in 10 years, that's pretty mild compared to most of North America and much of Europe. Presumably you live on the west or south coast.  It did get down to -12°C back in December 2010 where I live in central England, which is very rare, where the normal coldest night is -6°C. I didn't have an LEDs outdoors back then, but my parent's had some CFLs outside and they carried on working, although I believe they were the bi-pin type with the internal starter and external magnetic ballast.

I don't think it's the LEDs themselves which have a problem with the cold, but the electrolytic smoothing capacitor, which can increase in ESR at low temperatures. It would be interesting to hear someone's experience who lives in a colder climate.
« Last Edit: May 27, 2022, 09:34:46 am by Zero999 »
 

Offline wraper

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Re: I thought LED lights were efficient?
« Reply #68 on: May 27, 2022, 09:10:41 am »
I don't think it's the LEDs themselves which have a problem with the cold, but the electrolytic smoothing capacitor, which can increase in ESR at low temperatures. It would be interesting to hear someone's experience who lives in a colder climate.
ESR increases but not that much to break operation of something which is not broken by design and is not marginally operational at room temperature  (unless cooled to extremely low temperatures).
 

Online Zero999

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Re: I thought LED lights were efficient?
« Reply #69 on: May 27, 2022, 09:46:24 am »
I don't think it's the LEDs themselves which have a problem with the cold, but the electrolytic smoothing capacitor, which can increase in ESR at low temperatures. It would be interesting to hear someone's experience who lives in a colder climate.
ESR increases but not that much to break operation of something which is not broken by design and is not marginally operational at room temperature  (unless cooled to extremely low temperatures).
It wouldn't surprise me if a good number of LED lamps are prone to malfunction, or even failure at very low temperatures. The ESR of an aluminum capacitor roughly doubles, every time the temperature is reduced by 15°C. If the person designing the circuit chooses a part specified at 25°C, the ESR will increase by an order of magnitude at -30°C. The capacitance also drops off a bit and lower temperatures, which doesn't help.

https://www.avnet.com/wps/portal/abacus/resources/article/understanding-esr-in-electrolytic-capacitors/
https://www.researchgate.net/figure/ESR-versus-ambient-temperature-for-sound-capacitors-measured-at-66-kHz_fig1_29640251
https://www.dfrsolutions.com/hubfs/Resources/services/Uprating-of-Electrolytic-Capacitors.pdf
https://www.rs-online.com/designspark/suffering-from-esr-fluctuations-due-to-temperature-maybe-its-time-to-polymerise
 

Offline wraper

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Re: I thought LED lights were efficient?
« Reply #70 on: May 27, 2022, 10:25:57 am »
It will increase voltage ripple but not so much that lamp should stop working.
 

Online CatalinaWOW

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Re: I thought LED lights were efficient?
« Reply #71 on: May 27, 2022, 10:31:40 am »
Efficiency is good, but often isn't a sensible metric to drive replacement.  I have outbuildings used primarily for storage.  The lights are operated only a few hours a year.  Damage to the environment from the manufacture and installation of high efficiency units would exceed the savings in operation.  While LED lights would be better light, turn on faster etc. it just doesn't make sense to change them.  A shop used only some evenings and weekends is a less extreme case but may have the same answer.
 

Offline Siwastaja

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Re: I thought LED lights were efficient?
« Reply #72 on: May 27, 2022, 02:42:07 pm »
ESR increases but not that much to break operation of something which is not broken by design and is not marginally operational at room temperature  (unless cooled to extremely low temperatures).

Yes and the increased ESR causes increased power dissipation in the capacitor, heating it up, causing the ESR to drop again

In even remotely acceptable design, one could expect a tad more flicker in cold weather, especially for the first few minutes after turning on. But of course, everything is possible, you can fail designs in very peculiar ways, even if physics is on your side.
 

Offline NorthyTopic starter

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Re: I thought LED lights were efficient?
« Reply #73 on: May 31, 2022, 08:18:16 pm »
New lights are here, very flimsy, I think the knock offs I sent back might have been better built  :palm:

Oh well, never mind. I'm tempted to open them up and look at how they are driven. See if the LEDs are being grilled!

G
 

Offline NorthyTopic starter

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Re: I thought LED lights were efficient?
« Reply #74 on: May 31, 2022, 08:40:42 pm »
OK, I popped the ends off quickly.......

There is a driver PCB in each end of the light (although the mains wire only goes into one end). The PCBs look well made to me, but it’s also interesting that they don’t fit in the housing as it looks like they originally designed to do (there’s some small features in the plastic that are there to kind of hold a board) as they are smaller than the features and held in with that white snot glue stuff.

The main ‘body’ of the light is plastic, no aluminium to be seen - this also gives me hope they are not overdriving the LEDs and just producing heat? Maybe they have figured out that using more LEDs and no aluminium (as heat sinking) is the cheapest way to produce them.

Anyway, I'll fit them at the weekend and see how they go.

G
 


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