Just bought a couple of Muller Licht 4.8 W LED lamps from Aldi to try out at £4.79 each.
They have good Warm White colour and enough light (350 lm) for the intended landing nighlight use.
But I'm confused by the numbers. The headline "power" is 4.8 W but the rating says 230 V, 50 mA now that comes out at 11.5 W... Similarly the two CFLs that these LEDS replace are quoted at 13 W and
11 W but the maths on the quoted current gives 26 W and 22 W.
I'm not that familiar with power factor but it isn't going to make that much difference is it? What is that quoted current, in rush?
To add to the mix the "Energy Effciency Chart" says "5.00 kWh/1000h".
The LED lamp is certainly using less power as it's considerably cooler after 12+ hours of use than the 11 W CFL but how much actual power?
Power factor can make an enormous difference. So the first one has a power factor of 4.8 / 11 = 0.44 and the CFLs are both 0.5.
These figures are typical for switched mode power supplies without power factor correction (which is what most CFL and LED retrofit lamps use).
Lamps don't need to include power factor correction if they use less than 25W.
The specified current will probably be the RMS current rating - nothing else would make any sense in that context.
Have a look at
formatting link
Scroll down to the Switched Mode Power Supply example, and that shows you what the current waveform looks like at a power factor of 0.5. Drag the waveform left and right to see how the current waveform changes and impacts the power factor. (You will need Java enabled in your browser for this to work.)
Well, it should be 4.8W if it matches its claimed rating (which is actually 4.8kWh/1000h).
Interesting. So if one could get a more symmetrical waveform would one also perhaps generate less crap on the radio spectrum. Some cfls seem to be almost silent while others knock out 50 hertz modulated crap all over the place. That must be using power to generate, surely? Not got any leds yet to compare them to. I am a low user of light as I'm sure you are aware, but when folk come over it is required. Brian
Thanks, I didn't think (for no known reason) that they were that "bad".
Yes, I can see that if specing the wiring or protection one needs to know the *actual* current.
I shall have to kick java into working, it frequently asks to update but always fails to do so, can't access/find/download the file(s).
Presumably they aren't allowed to use decimal energys on those charts so it gets rounded up.
The bottom line is that my meter is going round at about 5 W rather than 10. Which means that these two LED lamps are roughly 50%/year cheaper to run even taking into account the capital cost:
2 x 13 W CFLs @ £0.48 each 10,000 hr life on for 21 hrs/day @
10.79p/kWHr = £23.42
2 x 4.8W LEDs @ £4.79 each 20,000 hr life on for 21 hrs/day @
10.79p/kWhr = £12.53
"Life" is from the packaging. The CFLs do seem to last at least that long, LEDs are far to new. The packaging gives the lumen output of the CFLs at 900 and the LEDs at 350. Yes they are a bit dimmer but preception is not as great as I would expect from 900 to 350 change(*). They are good enough for "night light" illumination of a corridor with no natural light.
(*) Presumably our peception is a log scale and lumens linear. So 350 to 700 lumen would only be a "3dB detectable difference".
The actual current will be several times the rms current, but only drawn in narrow pulses twice a cycle. It has the same heating effect in the bulb as the rms current.
Nowadays, no one should leave java enabled in a browser - it's too big a security risk. I wrote this a long time ago, when all browsers did have Java, and Sun was much more open and responsive on security issues than Oracle is. However, you will have to temporarily enable it for this page to work. It doesn't need up-to-date Java - I deliberately wrote it using the oldest version I could find (Java 1.3 IIRC), so it will work with any version you will find back over the last 10 years.
I should rewrite it to use javascript (which has absolutely nothing to do with java).
BTW, this was a prototyping page - the final one (which was more fully featured) was on blogs.sun.com, but was taken down by Oracle about 4 years ago due to not being sufficiently work related.
It's stange they wrote 5.00 - if they'd just written 5, it could be argued to be near enough correct!
To see what their light output is, don't look at the bulb, but look at a surface they light up, under equal conditions. Ideally, you take into account all the surfaces you care about (walls, floor, ceiling, etc), as they might well have different light distributions.
Doesn't really work that way at all for sight. Your eyes are able to compensate over a wide range by using the iris, and the only impact is a change in depth of focus due to changing f number.
Once you drop below the point where the iris is fully open and can't open any further, you start to loose detailed colour perception first.
If you have any uncorrected long/short sight or reduction in accomodation (i.e. over 50 years old), then the reduction in depth of focus will be most noticable at these lower light levels, as difficulty in focussing.
At 8k75 hrs per year that's just short of a year's continuous running for t he CFL's and double that for the LED's - and coincidentally 24/21 x 8750 gi ves 10,000 so your CFL's are lasting a year, etc.
But, and I have banged on about this previously, there is no way that a rel iable SMS can be built into a light bulb foot - trade-offs will have had to be made to get the fit. The lighting diodes themselves will have a far gre ater life than the electronics. It will be interesting to see what life Da ve does get from these bulbs as his use is pretty near constant running, th ough any turn-on/turn-off regime does impact on the life of any electronic item.
In terms of perceived light output, I replaced 2 off 35W 12v halogen down l ighters in my hall with 4 off 3W COB 12v LEDs in double holders; the impact was really significant in terms of light distribution and output. The tran sformer was cheaper than one bulb and is not size limited so should have a good life, but unlike Dave's set-up, these lights are on/off several times a day.
To complete the comparison lets compare 20,000 hour's worth of CFL at
26W total against the 20,000 hour's worth of LED at 9.6W total. Forget the 21 hours per day, it's a needless complication at this stage.
4x 13W CFL costs = £1.92 plus 20 kilo hours at 26W = 520 units at
10.79 pence per unit gives a total running cost of £56.11 + £1.92 = £58.03.
Doing the same calculation for the dimmer LED lamps gives a total lamp cost of £9,58 and an electricity cost of £20.72 which gives a total running cost of £30.30
If you level the playing field so that the LED case is only 1db down in lighting intensity on the CFL case by doubling up on LEDs, the costs for the LED lamps you've chosen for your example doubles up to £60.59.
The TCO in the long term (20 kilo hours at 21 hours per day = just over 2 1/2 years) is almost exactly the same in both cases with the CFL working out slightly cheaper for a fraction more light.
When it comes to the 10,000 CFL lamp life period, the TCO for the CFL case is exactly halved to £29.02 whilst that for the LED case, notwithstanding that there's another 10,000 hour's worth of lamp life remaining, works out at £39.88
For anyone else contemplating an LED lamp 'upgrade' from CFL, it's well worth remembering that unusually high 21 hours per day 'burning time'. For the more usual average daily lamp 'burning time', you can conservatively double those payback time periods to 2 1/2 and 5 years respectively. It's also worth bearing in mind that you're paying ever so slightly more for an ever so slightly less lumen output in the LED case.
That's true for the variations typical of most natural daylit scenes, less so, tending to being more 'linear', under conditions of artificial lighting levels typical of most domestic environments which are much lower.
In photographic terms, that drop corresponds to one stop's worth of reduction in exposure (or a halving of the exposure time - next faster shutter speed - when all else remains equal (illumination level, F stop number and film speed/sensor sensitivity)).
It's a noticable darkening in the resultant photograph if no post processing compensation is applied but since a typical film camera could only offer shutter speeds varying by a two to one ratio and likewise most lenses were usually limited to F stop values in a
1.414:1 ratio (halving or doubling of the aperture area).
Being within +/- 1.5db of the optimum exposure levels was deemed to be sufficiently accurate for most practical photographic purposes, especially with negative print film where finer adjustments could be applied during the final positive printing stage.
At typical domestic lighting levels, the iris of the human eye is pretty close to being maxed out on dilation (close to its minimum F Stop value) which reduces the depth of field as well as demanding more gain from the retina/visual cortex, resulting in less relaxing seeing conditions.
That drop in illumination is akin to substituting a 100W halogen lamp with a standard 60W tungsten filament lamp. Since typical CFLs are barely capable of matching a 100W tungsten filament lamp, the halving of illumination level is going to be significantly less comfortable for visual tasks involving fine detail.
The drop in lumens will usually be less critical for hallway and landing areas so your 350 lumens might well suffice in this case even though the figures suggest a 4.1db drop in level rather than the more modest 3.01db you used as a rough approximation.
As things stand, despite the latest higher efficiency and higher output LED lamps that are beginning to go into production, the current crop of 'cheap' LEDs in the likes of Aldi and Lidl are the older less efficient types currently clogging up the distribution channel.
What retail sources there are of the modern high efficiency lamps, their prices will be even more expensive than the currently overpriced stock being shifted in Ikea and Aldi/Lidle stores.
Personally speaking, I'm hanging on until the new LEDs appear at more realistic price points that truly make a CFL to LED upgrade a real upgrade with an economic benefit that can be realised after a modest 4 to 5 year payback period.
This might happen after only another year or two to allow the old stock to be cleared out of the distribution channel and the benefit of mass production (and marketing) of the newer lamps to kick in. The existing CFLs do a good enough job now so there's no rush to jump on the LED 'bandwaggon' just yet.
No one may have done it yet, but that's not the same as saying no one can or will.
However largely there is no need. a capacitor makes a nice non power consuming way to drip the volts just as an inductor does in the case of a fluorescent.
They are fine for the no natural light and narrow corridor they are in. They would not be suitable for space lighting of even a small living room, table lamps would be OK.
I'd previously done the sums on CFL v LED so when I saw these at £4.79 and 350 lm more or less knew there would be a saving. The previous calculations had been based on around £10/LED blub, that difference in capital cost is what really brings in the savings.
Agreed, for general household lighting. They did have some 700 (IIRC) lm output 6 W LED's but they where at the £10 each price mark, so no gain to be made. Not to mention all our general household light fittings are BC and they only had ES...
It's a damn site better than it was at least they now put the lumen out put on the packaging so you can compare power consumption and lumens across a range of technologies.
I wonder how many of the great unwashed could actually do that though?
Well I uninstalled anything with Java and Oracle, downloaded reinstalled but can't find a way to enable it. There is a drop down menu with "Ask to Activate" and "Never Activate" (or similar) and it's set to "ask" but it never does...
That would be nice, the text is very good and with animated demonstrations it would excellent.
True but aren't these energy effciency charts governed by EU rules I would not be at all surprised to find that the rules insist on at least 3 digits and rounding to whole kWHrs. B-)
I did, yes they are dimmer but not dim enough to be a problem. Put it this way they have been in place a couple of days and SWMBO'd has not complianed. B-)
Short sighted, with presbyopia. Unaided focus range is between about
6" to 8". Anything closer or further away is out of focus, varifocals are great.
That is about how long they last +/- a couple of months.
For tungsten:
2 x 40 W @ £0.10 each 1,000 hr life on for 21 hrs/day @
10.79p/kWHr = £71.22
And about 18 bulb changes/year!
Yes I'm wondering how long they will last as well. They certainly run far cooler, the fitting is a flatish ceiling fitting with very little ventilation. After 12+ hours the LED was warm but only comfortably so, the glass fitting cover was just warm. The CFL was not too hot to handle but definately hot and the glass cover decidedly warm.
I doubt many but is that really the whole story ...
I tried working soemthing similar out for my hall light, I had a 1W LED a 7 watt CFL and a 25W rough useage standard bulb, and after working out which was best I decided that turning the light off and only turning it on when needed was the best option, with the 7w CFL.
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