LED filament bulbs

[harry]

Came across this, interesting.

[Max Demian]

What an odd idea. Make a super-duper LED lamp that emulates a pre-WW2 incandescent.

[Bill Wright]

Our local has them and they look really good.

Bill

[Dave Liquorice]

Well the "retro" type are available but the basic collection of straight filament sticks are (mostly) the most effcient domestic light bulbs out there at > 100 lm/W. They are my bulb of choice now, provided the price is right (

[critcher]

been available for quite a while.

[misterroy]

can you post a link to a lamp you are using Dave? thanks

[James Wilkinson Sword]

Bet you their life is even shorter than a filament bulb.

[Roger Hayter]

I think the important feature is not the shape of the filament, which in many applications you can't see, but the wide angle of illumination, which often works better in light fittings designed for traditonal incandescent lamps.

[John Rumm]

I find its actually a very good idea - I use them almost exclusively. The main attraction (other than being nicer to look at in applications where you can see the bulb) is the 360 degree radiation pattern, that closely resembles a GLS lamp. Hence any fittings that use the lamp cap down or the whole lamp side on, still give the intended illumination.

There is a second significant advantage, in that the strips are typically arranged into relatively high voltage chains such that they can be be wired in sets of 4 directly across the mains with no need to use dropper capacitors. Hence better reliability and less temperature sensitive ageing.

[John Rumm]

I would like to take the opportunity to thank harry for posting something actually on topic for once!

[news]

Does GLS have a standard size? I have one of these LED filament bulbs in my sitting room but the diffuser has a 65mm hole and won't fit over the bulb.

Any ideas for an LED with equivalent light output in a smaller bulb?

AJH

[Johnny B Good]

====snip====

I'm afraid that's most definitely untrue. The closer the 'filament' drive voltage rating approaches the supply voltage, the greater their sensitivity to supply voltage variations becomes in regard of their forward voltage drop conductivity.

LEDs can't be driven directly from a constant voltage source without risk of thermal runaway when being driven close to their operational limits typical of GLS applications. They need some form of current limiting whether a simple capacitive dropper that drops 30 to 70% of the supply voltage or else a more sophisticated electronic ballast that supplies a more tightly controlled constant current optimised for the LEDs used in the filament strings or the COB array.

Since my commissioning tests on each new LED GLS lamp I've purchased during the past 5 years or so have revealed a higher consumption than that claimed for these lamps in every case, I've finally come to the conclusion that it's a consequence of meeting a minimum Lumens output (typically a 60W equivalent of 810Lm) at the bottom of the 220 to 240 volt mains voltage range when powered from a 240v UK supply.

The first of the latest "High Efficiency" 68LPW GLS "60W equivalent" LES lamps bought from Asda about 5 years ago claimed a consumption wattage rating of 12W. Testing revealed that it was actually taking 14W but I wasn't bothered too much about that since it certainly provided far more light output than the 20W CFL "60W equivalent" it replaced.

The only downside being that it was rather heavier than the replaced CFL due to the use of a meaty well engineered finned heatsink which placed an extra burden on the height adjustable pendant luminaire over the dining table.

It was eventually replaced a year or two later with an even more efficient (and lighter) 81LPW "60W equivalent" LED with a claimed consumption of just 10W which measured pretty close to 12W. Again, the extra consumption wasn't an issue (but I was beginning to see a pattern emerging). The Asda branded lamp (part number: LDA12WE27COA3000K)[1] landed up in my Anglepoise desk lamp where it remains to this day. Interestingly, a recent test revealed a consumption figure of 13.5W which most likely was the result of the voltage being lower this time round compared to the original test voltage condition some 5 years ago.

More recently, I've seen the same sort of inflated measured consumption versus the rated consumption with the Poundland lamps - 6W versus 5.5 for the SBC 470Lm lamps and the later 510Lm versions. Even the three quid Home & Bargain 12W 1500Lm (125LPW) LES "100W equivalent" showed an inflated wattage reading of about 13.5W when I tested it before installing it into the bathroom light fitting which had housed the last remaining incandescent GLS lamp.

[1] Curiously, this Asda branded lamp quotes 50/60Hz in addition to the 220 to 240 volt supply @67mA (implying a PF of 0.85) which strongly suggests an electronic ballast more sophisticated than a mere dropper capacitor.

However, the 220 to 240 volt range seems to be more in keeping with UK and European supply voltages where 50Hz is the standard frequency of supply so it's just possible that the mention of 60Hz may simply be a matter of mislabelling (possibly a "force of habit" error).

The only other place where 60Hz is standard outside of the USA that comes to mind is Japan (well, roughly half of Japan - the other half does use 50Hz) so it seems a little unusual that a lamp designed to operate in the range of 220 to 240 should also include the 60Hz option.

Since ICBA to find a couple of 7AH SLAs to black start my spare APC SmartUPS700 in 60Hz mode, this claim of 60Hz compatibility is going to remain untested for the foreseeable future.

[Brian Gaff]

If it has a global light pattern then its sorely needed. Brian

[tabbypurr]

sounds like you're not up to date with the latest generation of LED lighting drivers. Not finding the link but basically they switch which LEDs are on according to the momentary mains voltage.

NT

[PeterC]

'Filament' LEDs are, AIUI, COB and are probably the least inefficient LEDs generally available. Morrisons have (had?) some 6W, 800lm, 'GLS' B22 lamps, unfortunately ~3000K (I prefer 4000K+) for a fiver each. I have one and it is good. I've not checked the actual wattage - OK, just for you:

5W is flickering 4 - 5 and is just under %W based on VAxPF 15W, 1500lm is similarly marginally low 60W incandesent shows 60W - surprising as the voltage is ~245. 5 years ago I wouln't go below 80lm/W; 3 years ago I considered only =>100lm/W, with exception for GU10 for desk and bench lights that don't spend long on.

Ikea changed to all Led, but those are worse than my benchmark 5 years ago!

BTW, I bought from Ledlam some lamps that have COB on ceramic blades. The blades are in a triangel and very translucent, with the 'back' of each blade shining throght th gap between the other two, so near enough 360 deg. The 3W is 320lm and the 5W is 600lm - this was 3 years ago! How progress goes - not!

[John Rumm]

Yup, actually I would agree with that ;-)

I am both over simplifying and typing faster than I was thinking!

They do of course include current limitation - and that quite often is a capacitive dropper. However what I was getting at was that they often have less "complicated" drivers - and can quite often get away without using electrolytic caps commonly found in many switching supplies, which seems to be the weak spot of many.

Many use a (simple) RC network as a current limit, usually then feeding a bridge rectumfrier. The individual strips usually have a forward voltage drop of around 60V. Often strung with a couple in series (paralleled up on the higher wattage versions). That means you are dropping around half the voltage in the supply. Many seem to slightly under run the filaments (although that may be a reflection of the voltage range they are designed to cover).

(personally I am less worried by a small loss of efficiency fron under running given the relatively low power anyway such that the gains are fractional watts)

Most of the "60W" ones I have claim 740lm IIRC. Oddly I noticed some recently where they lumens figure was actually lower on the daylight version.

Do you know if that was a true power 14W or was there a reactive component in that figure?

I recall someone trying to use an (early ish) CFL in an anglepoise. The results were fairly predictable!

Possibly just someone specifying something they felt ought to be in the spec... (wither that or they had a job lot returned from someone trying to use them on an aircraft 400Hz supply ;-)

Yup, there are some things that even enquiring minds don't really need to know!

[Huge]

I got a "candle" format GLS BC LED from somewhere for a table lamp with a glass globe that has a small hole and won't fit over a incandescent bulb, much less a standard LED one. I think it came from B&Q.

[whisky-dave]

One that I brought lasted under 3 hours. Not sure what happened. It was a 4W=40W with 4 'elements'.

[news]

Ah but was it 11W and 1440 lumen? This is what we have currently without the globe and I don't want to lose too much light if I refit the globe.

AJH

[Graham.]

That sounds like a terrible idea.

JR, JbG and even AG can argue the toss, but if Big Clive Mitchell isn't aware of it, it's not happening. ;-)