Recommendation for LED lighting - Page 1
Forum section: electronics / general

author: Ranayna
author_rank: Super Contributor
timestamp: November 14, 2018, 01:54:19 pm
content: I'm not entirely sure where this belongs, so if this is not the right place I will move it...I am looking to replace my old Halogen lighting with LEDs.The current setup is as follows: 4 groups of 3 35 watts 12V Halogen reflector bulbs with GU5.3 sockets. Each of these groups is individually switchable and therefore has its own halogen transformer (230V to 12V). All the cabling and the transformers are lying loosely in a suspended ceiling. Space above the ceiling is only about 15 centimeters at most, only access to the ceiling are the holes where the lamps go.I do not have much experience with LED lighting except for standard replacement bulbs. This forum is about the most trusted knowledge base I know of, so I'm looking here for help.I want to keep the existing lamp holders if possible, I definitely do not want to make new or bigger holes.I am willing (and expecting) to replace the transformers, the existing ones are now nearly 15 years old.I want reasonable quality, no china crap, but also no "lightingphoolery" (does that exist?) expensive stuff, although I would prefer as little flicker as possible.No dimming required.Ideally it is a system similar to the existing one, with one transformer for 3 bulbs. That way I would not have to touch the mains cabling, and I would expect the bulbs themselves can run cooler (and therefore live longer) with an external power supply.It should be available in Germany, or at least within the EU.What products can you recommend?Greetings,Ranayna

author: james_s
author_rank: Super Contributor
timestamp: November 14, 2018, 04:46:34 pm
content: I've had good luck with Philips and Cree, I'd start by looking at their offerings.

author: Ranayna
author_rank: Super Contributor
timestamp: November 19, 2018, 09:28:37 am
content: Is there a site that does safety tests and teardowns of LED transformers?There are so many models and manufacturers, most of which I have never heard of, and the prices span from ridiculously cheap to absolutely outrageous.I am just not sure what to get, especially since it will be completely out of sight and out of mind in the ceiling.I do not want to wonder one day where the burning smell is coming from

author: Kjelt
author_rank: Super Contributor
timestamp: November 19, 2018, 02:01:51 pm
content: I would then recommend switching to GU10 230VAC, the fixtures should match (size of the hole) and are aprox. €6-12 a piece depending on brand etc.I have even seen €12 for three pieces on certain low price shops.Then you can start simple with the standard good brand GU10 ledspots, you could keep the group based switching by adding a rectifier and a 12V relay per groupOr as your budget or requirements grow, go all the way to Philips Hue GU 10 spots, available in white (you can choose the colortemperature and dimming for each light individually or group certain lights together in groups) or even color.

author: Ranayna
author_rank: Super Contributor
timestamp: November 20, 2018, 08:40:56 am
content: Well, that is not really what I want.I know the theory of setting up a new junction box and all that, but I am not really comfortable doing stuff like that. Heck, I think I am actually certified for doing electrical work from my vocational school, but it now has been over 10 years since. I know enough that I do not know enough to actually touch that stuff for anything more than replacing a lamp holderReplacing a transformer is something I'm sure I can do.Originally I wanted to order everything at Amazon, but I have changed my mind now. I will order this transformer from ELV:https://www.elv.de/elv-30-w-led-netzteil-12-v-dc.htmlWith these LEDs:https://www.elv.de/osram-led-star-4-6-w-gu5-3-led-lampe-mit-glasreflektor-neutralweiss-12-v.htmlThey are a well known electronics shop, the transformer is branded by them. I trust them enough to give it a try. Hopefully the thing is not potted so I can give it a short teardown.While I cannot do any real safety tests, I could at least evaluate the general build quality.

author: Kjelt
author_rank: Super Contributor
timestamp: November 20, 2018, 11:09:43 am
content: The transformers are those the oldschool heavy metal copper transformers? If so , don't change them , they will outlast you.If they are the low weight electronic transformers it might be a good idea to upgrade them.

author: Ranayna
author_rank: Super Contributor
timestamp: November 20, 2018, 12:00:05 pm
content: I don't know the exact type yet. I remember them being rather small though.Also, they are halogen transformers. I heard that it is not really recommended to keep using them for LEDs, since supposedly their output voltage is not well regulated and may be high, especially when only lightly loaded.

author: Kjelt
author_rank: Super Contributor
timestamp: November 20, 2018, 12:20:00 pm
content: Yes better to change them for dedicated drivers.Note: the driver you picked is not dimmable, that might be an issue if the new led lights are too bright.

author: macboy
author_rank: Super Contributor
timestamp: November 20, 2018, 03:27:02 pm
content: I filled my house with Luminus brand LED bulbs of various types, bought from Costco (big box wholesale store) in Canada. They were specified as 3000K and a CRI of ">90". The CRI is Color Rendering Index and specifies what % of human visible color spectrum the emitted light actually covers. Higher CRI is obviously better, and >=90 is very good. Many cheap ones are well under 80. I really like the 3000K white, it is much less yellow/orange than incandescent, and is similar to Halogen bulbs. I very much dislike any LED with color temperature above about 3300K. Those usually have a strong blue spike in their output which I find cold, harsh, unpleasant. At first I only bought a few bulbs for a room or two, but I could immediately see the improvement in color perception over the older LED bulbs I was using, and so could my wife and kids. That's when I realized that the CRI isn't just marketing wank. I went back and bought enough for every fixture in my home (and many extras).I strongly recommend looking for LED lighting with a specified CRI of >=90. If a high CRI is not proudly specified on the marketing/packaging, then there is probably a reason for that, i.e. it isn't good enough.

author: Kjelt
author_rank: Super Contributor
timestamp: November 20, 2018, 06:21:40 pm
content: Unfortunately cri is an old conventional lighting based index, for led new standards were in the making, i don't know the current status.Quotehttps://indiecinemaacademy.com/is-cri-relevant-in-an-led-world/

author: james_s
author_rank: Super Contributor
timestamp: November 20, 2018, 06:27:58 pm
content: CRI has been widely used for decades and still applies to LEDs. It's imperfect but so is any other way of measuring the color rendering. The old fluorescent lamps had a CRI in the low 60s, that is the reason fluorescent light is often considered harsh or drab.

author: Kjelt
author_rank: Super Contributor
timestamp: November 20, 2018, 06:35:25 pm
content: There are for over 30 yrs fluorescent lights with cri>90 used in the graphical industry.Expensive, they have a lot of different phosphors.I have worked over 10 yrs in this domain, CRI is applicable for black mass radiators with a wide color spectrum not for leds. Nobody wants you to know that and the industry does its best to make it better but fact remains CRI can not be used in the same way to compare led lighting vs conventional lighting.

author: nctnico
author_rank: Super Contributor
timestamp: November 20, 2018, 06:51:22 pm
content: Quote from: james_s on November 20, 2018, 06:27:58 pmGood CFL tubes have very high CRIs (IIRC >95%) nowadays. But you shouldn't buy the cheapest ones. The same goes for LED lamps: don't buy the cheap crap.

author: james_s
author_rank: Super Contributor
timestamp: November 20, 2018, 09:16:41 pm
content: Quote from: Kjelt on November 20, 2018, 06:35:25 pmThat is true indeed, however they have a significant penalty in light output per watt of electricity consumed. IIRC the 90+ CRI fluorescent lamps achieve only about 60-70% the efficiency of the lower CRI lamps. The main reason for low CRI in discharge lamps is the lack of true red light, and to get higher CRI they add a true red phosphor (yttrium vanadate IIRC) which emits a nice ruby red color but it is not very efficient.Older fluorecent lamps used a halophosphate phosphor which emits a broadband from blue through orange which can be tweaked from a cool daylight to a warm orangish with a CRI in the 60s. Modern higher CRI lamps use a trichromatic blend, individual red, green and blue phosphor compounds which are mixed to produce the desired hue.

author: nctnico
author_rank: Super Contributor
timestamp: November 20, 2018, 10:36:43 pm
content: Quote from: james_s on November 20, 2018, 09:16:41 pmAlso old information. The high CRI CFLs tubes (intended for use in the graphics industry) I have from Philips (TLD Master 950) are on par with the efficiency of LED lamps.

author: james_s
author_rank: Super Contributor
timestamp: November 20, 2018, 11:25:04 pm
content: Quote from: nctnico on November 20, 2018, 10:36:43 pmI'm not comparing them to LEDs, I'm comparing them to more common 80+ CRI fluorescent lamps. Here's the data straight from Philips:First the TLD Master 950 you mention, looking at the common (in the US) F32T8 size which is a 4' long 1" diameter tube:http://www.lighting.philips.com/main/prof/conventional-lamps-and-tubes/fluorescent-lamps-and-starters/tl-d/master-tl-d-90-graphica/928044795081_EU/productThe most interesting bits:Luminous Flux (Nom) 2330 lmLuminous Efficacy (rated) (Nom) 65 lm/WNext the TLD super 80 which is a trichromatic lamp with a CRI of 80+:http://www.lighting.philips.com/main/prof/conventional-lamps-and-tubes/fluorescent-lamps-and-starters/tl-d/master-tl-d-super-80/927921084069_EU/productLuminous Flux (Nom) 3350 lmLuminous Efficacy (rated) (Nom) 93 lm/WSo from that we have >80 CRI lamp is 93 lm/W vs >90 CRI lamp 65 lm/W. I said previously that the 90+ CRI lamps have a penalty, achieving around 60-70% of the efficiency of lower CRI lamps, which matches the information above, both F32T8 which are nominally 36W, looking closer I believe these are a European product, in the US F32T8 lamps are 32W. All this is straight from the horse's mouth so to speak.I don't have the data on hand but IIRC the efficiency penalty between low and high CRI lamps of the older halophosphate type was similar, the newer rare earth trichromatic phosphors offering a significant boost in efficiency but to get the 90+ CRI you still need to add a true red phosphor and in doing so you sacrifice efficiency. In many cases this is a worthwhile trade, but my point still stands that there is no free lunch. The reason 80+ CRI lamps are so common is that they are generally considered the best compromise between cost, efficiency and light quality. For applications where color rendering is less important, there are 70+ CRI lamps which are cheaper and even more efficient. For applications where color rendering is more important, there are 90+ CRI lamps but they cost quite a bit more and as demonstrated above, come with a significant penalty in lumens per Watt.Now I don't have data in front of me for a lot of LED lamps but I do recall some of the more recent A19 size LED bulbs I got having a claimed efficiency of right around 100lm/W with a >80 CRI however I have not looked at the current state of >90 CRI LEDs so I can't say whether they suffer a similar reduction in efficiency or just cost more. Trying to compare efficiency between bulbs and tubular lamps is also complicated by the often significant difference between lamp efficiency and system efficiency. There is a great deal of variation in how much of the light coming out of the lamp ends up getting to where you want it.

author: Kjelt
author_rank: Super Contributor
timestamp: November 21, 2018, 11:09:01 am
content: Quote from: james_s on November 20, 2018, 11:25:04 pmOfcourse, the Lm is according to the human eye sensitivity to wavelengths and the human eye is for red less sensitive than for green.If you want a good reproduction you need a nice even light across the entire spectrum.QuoteLED in the long run will have a higher eff. than fluo, no doubt. But the CRI still means not the same for led as for fluo, don't make that mistake.You can have three different brands of CRI 90 leds and still they can all look totally different and you can be sure they are unusable for the graphics or movie industry. There are ledlights that add red leds and other colors and a large diffuser to compensate, those are ok but single white leds AFAIK still have not the same color representation as conventional lighting.

author: Kjelt
author_rank: Super Contributor
timestamp: November 21, 2018, 11:46:32 am
content: Reading material:https://www.digikey.com/en/articles/techzone/2014/aug/illuminating-the-limitations-of-cri-testing

author: Ranayna
author_rank: Super Contributor
timestamp: November 23, 2018, 01:39:51 pm
content: I have gotten the transformer now.The thing is not potted, and just clipped together. The case feels somewhat flimsy. There is no "Made in..." mark. On the inside, it looks very similar to many laptop power supplies. Most is hidden under headsinks or white silicone rubberIsolations looks adequate, there are no slots, but the board seems to be conformally coated. There is what I assume to be a temperature sensor glued to a heatsink on the secondary, and the manual mentions a thermal shutdown function.The transformer has approval marks for suspended ceilings and furniture mounting.One thing interesting to note, and for many here a definitive negative point: CapXon capsAt least the ones where I can see it are rated to 105 degrees.A small discrepancy I found in the manual: The label on the transformer, on the primary, says 0.5mm2 to 1mm2 cable, where the manual says I must not use any lower than 0.75mm2Sorry, I cannot make pictures at the moment, I will see if I can provide some later

author: Kjelt
author_rank: Super Contributor
timestamp: November 23, 2018, 04:18:51 pm
content: The Capxon, Maxxon etc are decent elco bands these days. A brand manufacturers will use them as well to keep the BOM competitive.No they are not to the extreme quality standards as some japanese elco manufacturers go but they will survive 10 yrs which is ok for consumer stuff.You hear nobody complain when their tv dies after five years.

author: Ranayna
author_rank: Super Contributor
timestamp: December 03, 2018, 08:21:47 am
content: I don't really mind the CapXon caps. They are in everything affordable nowadays, and that in turn of course will bring about more tales of them failingAlso I wouldn't be surprised if those are counterfeited sometimes.Anyway, the refit was a success, and I have already ordered the materials to change the three other groups. The new lights are slightly less bright than the 35 watt halogen bulbs, but they (subjectively of course) seem to give nicer light. The halogens have more glare, if that is the right word. One interesting nitpick would be that it takes about a second for the light to turn on after the switch is hit. I assume it takes that time for the regulation to kick in, since the new transformer is at least a magnitude more complex than the old one.The old transformers really needed replacement. They are labeled 35-105 watts, which indicates what I assume is a minimum load. That might explain when several years ago, we just tried to change the bulbs to LED, without knowing anything about the system yet. Those just flickered and we gave up on retrofitting at that time.