LED replacement for halogen lights - Page 1
Forum section: electronics / general

author: galvanix
author_rank: Contributor
timestamp: September 18, 2021, 09:45:28 am
content: Hi,we would like to replace some of the halogen lights (G4 socket, 12VAC) in our kitchen with LEDs to save on electricity costs (~0.3€/kWh here in Germany).Unfortunately, most of the stuff I can find on Amazon is labeled with a color temperature of 3000 K but still seems awfully blue-ish and "cold". I have a hard time finding LED replacements of lower color temperature.Another important factor seems to be color rendering index (CRI) which apparently is horrendous for LEDs and makes the colors appear washed out/desaturated. Could this be another contributing factor to the LED lights looking "cold" (blueish)?The third issue seems to be flickering. Some LEDs like to flicker when run off of 12VAC 50 Hz systems. I think this shouldn't be an issue with a rectifier and filter cap but apparently it is.Do you have any experience with good CRI, low color temperature LED replacements for halogen bulbs?

author: GLouie
author_rank: Regular Contributor
timestamp: September 19, 2021, 04:09:46 pm
content: I do not have specific experience with home halogen replacements.Most "white" LEDs output strong spectral regions, leading to strong color tints and poor color rendition due to missing spectra. For example, some white LEDs look very blue and have little output in the red region, leading to the flat, cold look.You can get white LEDs at verious color temperatures and CRI. These two figures do not comprehensively describe everything about the light output, but they are common and very helpful.A color temperature of 3000 Kelvin should be similar to an incandescent and often described as yellowish compared to natural sunlight. Color temperatures like 5000K are usually described as bluish, but closer to natural sunlight.There are LEDs that have a high Color Rendering Index (CRI). Typically any CRI above 90 is considered good, where an incandescent is 100CRI. High CRI LEDs will cost more and have less efficiency. You can also find photo light panels with a mix of colored LEDS and adjustable color temperature with good CRI.I don't know about flicker in these, but can guess that if each socket is fed AC, that the individual lamps do not have good rectifiers or filters. Perhaps they are not large enough to house them.If you find an LED with a high CRI and color temperature of 3000K, it should not look blue. But some people prefer a higher color temperature to look more like daylight. Beware of products that overdrive the LEDS - trying to get more light from them then recommended. They will burn out quickly.

author: Zero999
author_rank: Super Contributor
timestamp: September 19, 2021, 04:25:53 pm
content: Go for 2700k LEDs.The reason for the flicker might be the electronic transformer used for 12VAC, produces a high frequency and doesn't work well with some LED lamps. Fortunately there are some 12V LEDs specifically designed to work with high frequency transformers.

author: deadlylover
author_rank: Frequent Contributor
timestamp: September 20, 2021, 05:17:51 am
content: Good replacements probably don't exist, so you'll just have to find something you can live with IMO. (even for normal sized bulbs, theYuji LED bulbsare one of the best you can get but aren't quite at "top tier" level yet for LED lighting)At least if you go with a trusted brand like Philips/Osram, it's extremely unlikely that the seller/store will mislabel the colour temperature. The Philips 2W G4 bulbs I can get at the local hardware store at least have a data sheet with the CCT and CRI (3000K, 80 CRI, still sucks but we don't get a choice).I've used a bunch of Philips LED bulbs (B22 base, typical for old Aussie homes) around the house and they kind of drop like flies after a year or two. Light output quality is terrible but there isn't much we can expect for a bulb the price of a Big Mac.It sounds like you're aware of CCT and CRI, but another important metric is the tint (Duv, deviation from the blackbody locus). Lots of LED lighting has a positive Duv or a "greenish" tint, and it's hard enough finding something neutral let alone negative Duv or "rosy". Even those Yuji bulbs linked earlier have a disgusting green tint as they lie above the BBL.Attached is a photo comparison I did for some torch enthusiasts. Bottom left is a typical LED bulb you can buy from the store, bottom right is using a LED strip with arguably the best LEDs on the planet (Nichia Optisolis, used for art galleries and museums). You probably don't even know it but I feel like a lot of people hate most neutral-cool CCT LED lights because of the tint, and many gravitate towards warmer temperatures because the green is a little less noticeable, but it's still there.Don't even get me started about the CRI R9 values, and how many "high CRI" lights have R9 values of 50 or lower.

author: james_s
author_rank: Super Contributor
timestamp: September 20, 2021, 05:56:22 am
content: What wattage are the halogen bulbs? I have found some reasonable LED bulbs I use in my landscape lighting, they are funny looking wedge shaped COB things that contain a switching regulator so they don't flicker on AC, at least not that I can detect and I'm pretty sensitive to flicker, the ones I have are only 2W though equivalent to about a 15W halogen. They are pretty close to 2700k but I don't know what the CRI is. The problem with all the random Chinese lamps is you never really know if the specs are accurate and usually they aren't. They do come in a lot of different shapes and sizes though, more variety than the better brands.