LED Light Bulb Efficiency - Page 1
Forum section: electronics / general

author: gnuarm
author_rank: Super Contributor
timestamp: December 26, 2022, 10:45:55 pm
content: I have seen variations in the reported efficiency of LED light bulbs and it does not seem to correlate with price. I'm wondering if there is any trade off between the things done to improve efficiency and life span of these products.There is a clear impact on longevity from higher temperatures. Things that help cool the light bulb cost money. But I can't think of how this would correlate with efficiency, other than a cooler LED working at a lower voltage, so more efficient.What would negatively impact the efficiency, or the life span, that would trade off between the two?

author: Zero999
author_rank: Super Contributor
timestamp: December 26, 2022, 10:59:26 pm
content: Yes cooler LEDs are generally more efficient, although that also depends on cooling, so it doesn't always correlate.Using a switched mode, or capacitive dropper is also more efficient, than a resistor, or linear regulator, although there are efficient lamps with linear regulators, which don't drop much voltage.Go for as lower current density as possible. You could buy a lamp, with much larger power rating than you require and hack it to a lower power, by replacing the dropper capacitor with a lower value, or changing the current sense resistor for a higher value. Sometimes more than one current sense resistor is used and all that's required is clipping one of them off with some cutters. YouTuber Big Clive has done numerous videos on this.

author: Thunderer
author_rank: Regular Contributor
timestamp: December 27, 2022, 12:26:51 am
content: Maybe you have an application where even the last mW gained counts.If not, and you just want to make a link between price and quality/efficency/heat dissipation, it is simply futile.When choosing a light source, one should first check and choose based on your needs. Work or living ambient (light colour). Light intensity (lm/W) which gives you an idea on the supposed efficiency. The build of the fixture, more plastic means heat dissipation issues = short life. Then, quality factors like CRI or R9, to make sure you invest in the best light source for your eyes. These quality factors will decide regardless of the first ones qualities.If you buy the LEDs to build yourself the fixture, make sure you start with components with datasheet. If the datasheet is about 15-20 pages long, you are on the right path. 1-2 pages is a sign of a poor quality component. Decent LEDs go beyond 100lm/W and cost next to nothing. For best LEDs we go beyond 120-130lm/W.Read application notes about implementing a good lighting solution. Rule of thumb 30% maximum loading of the LEDs (if we have a 3V and 1W LED, load it at maximum 100mA) and you will leave your lighting fixture as a heritage to your kids.

author: Thunderer
author_rank: Regular Contributor
timestamp: December 27, 2022, 12:30:25 am
content: Quote from: gnuarm on December 26, 2022, 10:45:55 pmNo electronics enthusiast should think about voltage when discussing LEDs, LEDs are current devices.

author: IanB
author_rank: Super Contributor
timestamp: December 27, 2022, 02:07:27 am
content: Quote from: gnuarm on December 26, 2022, 10:45:55 pmTo put it in a nutshell: if, for a given light output, a light bulb is constructed with more LED elements, each running at a lower current, then the bulb will tend to be more efficient and last longer, but will be more expensive to manufacture. Typically the higher cost will be passed on to the consumer, so on average, you can expect cheaper bulbs either to fail faster, or to have lower light output, or both. I found a dollar store bulb to have lower light output than a premium bulb, for the same claimed lumens.Having tested a few bulbs with the same claimed lumens, I have concluded that the number is not the actual measured light output, but is rather a "marketing claim", and in general, cheaper bulbs produce less light than more expensive bulbs for the same claimed lumens and power consumption.I have also found that the claimed power consumption (e.g. 8 W) is usually pretty accurate.So if you want the best lumens/watt from a bulb, then I would go for the more expensive ones. I have been finding that Philips bulbs perform better than most in my tests.The other important factor is dimmability. In the USA, dimmable bulbs cost far more than non-dimmable bulbs, presumably because of the more complex circuitry. I have found bulk buys on non-dimmable bulbs at a few cents per bulb (but I had no idea what to do with a carton of 24 bulbs for $9.99 when I only needed six).

author: jonpaul
author_rank: Super Contributor
timestamp: December 27, 2022, 02:08:28 am
content: Bonjour LED efficacy is not simple to measureTrade-offs as always are cost, efficiency and reliability.Good ballast design will fully comply with EMI, PFC, safety, cheapo, perhaps not.The best in EU are Philips and Sylvania. Bare LED modules for experiment are from CREE.Sylvania Belgium R&D développement of filament LED, evolved to the color controlled Helios linear lamps, 200 L/W, any desired color balance and life limited by breakage.Consumer LEDS will vary greatly in efficiency and life. We use filament LED screw or bayonet bulbs.Our designs in 1990s ( -CFL, HID) had bus caps 135 Dec C if lytics. Mains transients protection. Used resonant mode soft switching.Jon