LED Strip lighting

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gangstead
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LED Strip lighting

I’ve been reading up on the forum and I’d like to build some under-cabinet lighting. I’m looking at buying from a domestic seller to avoid the Chinese seller’s lottery. These strip lights from SuperBrightLeds claim 93 CRI and 511 Lumens per foot.

Under my cabinets I won’t have a run longer than about 4’ and I plan on driving them from both sides to avoid problems with voltage drop. My cabinets are already wired with 120V fluorescents so I plan on getting a small DC power supply under each (4’ should be 16.8W, so I’d get a 20-30W power supply for each cabinet).

My questions for anyone who’s done this or considered it: do the lights need to be attached to aluminum strips to sink the heat to reach the full rated brightness or can they be stuck directly to the wood of the cabinets? How much does the light from individual diodes blend together? The same store sells aluminum channel with frosted lenses, but that costs almost as much as the led strips. If it looks like spotted lights underneath there my wife will make me rip it out and go buy something pre-built – buying twice is not very budget friendly.

Am I better off buying pre-fabricated cabinet lights? The options at home depot seemed not very bright, not very attractive color options, unknown (presumably horrible) CRI, and few length options. I’ve currently got 3’, 2’, 18” length lights below the cabinets and 3’ and 4’ above. All are fluorescents in a dog’s breakfast of colors and sizes.

hank
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MtnDon
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A year or two ago I bought some from an ebay seller, shipping from China. They were advertised as 4500 or so IIRC. I used some in the kitchen. I did mount them in aluminum extrusions. After they have been ona while they are kinda hot. I don’t know that I would like them w/o any heat sinking? The cabinets get warm feeling on the upper side where they are mounted. You could probably get away with sticking the strips to flat strap aluminum. ?

I used more in the shop. Stripped thr old F40 fl tubes out and stuck the strips with 2xsided tape.

We like the color, can’t say how the cri is, but looks ok to us.

No hot spots apparent to the eye. No lenses / diffusers used either. It was much cheaper than ready made fixtures. China direct was cheap,cheap,cheapcompared to sb-led.

gangstead
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MtnDon wrote:
China direct was cheap,cheap,cheapcompared to sb-led.

I’m not committed to SB-LED, but I’ve always gotten exactly what I’ve ordered from them and they provide the most specs up front. I’ve seen on the other major thread on LED strip lights that no matter what the seller says the quality and specs are completely unknown when you order from China. That doesn’t bother me on $10 flashlights, but this is something that has to get spousal approval. I did a quick aliexpress check and see LED strips for less than $10, or about $30 if I include “High CRI” in the search. The High CRI, high brightness SB-LEDs strip is over $140, and $60 for the one that is 20% as bright , but still High CRI.

Is the American shipping markup 400% – 600%? Are the Chinese ones going to be radically different specs?

How is the brightness on yours? My concern is that since I’m replacing fluorescents I want something to be about as bright. For example one cabinet has a 3’ T12 (2350 lumens according to Philips). Using the brightest single LED strip at SB-Led at 511 lumens/ft is 1500 lumens, in the same ballpark. Using the numbers on one of the AliExpress sellers of 100 lumens/ft means I would only get 300 lumens in that space, and those are Chinese lumens so it could be even less. I can’t suffer the embarrassment of “Is it on yet?”

I wish I knew who the Convoy of LED Strips was: a reliable seller, accurate specs, good quality, not the lowest price but best for the quality.

MtnDon
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We are pleased with the brightness of ours. We had no lights under the cabinets to compare to. I started with only doing the cabinets in our cabin so the initial expense was only about $15 for a roll strip and one power supply. Then I did the home kitchen and used the left overs in the garage. The power supplies cost more than the LED’s. The strips I have use 5630 size. I can’t find the purchase details, must have been bought in 2013 as the purchase history only goes to 2014. Ebay.

I figured I would risk the initial outlay as it was still much cheaper than just one single light if bought from Lowe’s. Maybe I was lucky, maybe I’m not as discriminating as others.

hank
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Note you can now get combination driver/dimmer switches that go into the standard wall switchbox, available various places.
Here’s one: https://www.diodeled.com/switchex.html

Pricey, but eliminates putting a 12v transformer up in the attic or under a cabinet.

Lithopsian
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The specs put out by even the more reputable domestic suppliers are usually unrealistic, for example just multiplying the maximum power rating by the number of SMDs. As for stuff from China, might be cutting edge, might even be what you thought you were buying, but don’t trust any numbers even if they give them. Still, occasionally even Asian suppliers give realistic numbers, and occasionally you get something better than you ordered Smile

If you can see the tape well enough, and if you trust that it is actually what you’ll be buying, then you can calculate a realistic specification from just the resistor values. In theory you need to know the forward voltage current relation for the SMD but they’re all more or less the same. So having said that, I have no clue what a 2016 SMD is. A typo?

To use gangstead’s link as an example, the resistor is clearly visible and says 121 which means 120 ohms. There are two resistors for seven SMDs per 24V. These are going to be running at pretty low power, so assuming a 3.0V SMD drop, the resistor also gets 3.0V giving 12.5mA and 0.0375W/SMD. For total power add in 0.0375W for each resistor and also a tenth or two of a watt losses per foot of tape (and another 10-20% in the power supply!). I used pretty numbers, but in practice there is very little difference by assuming a different forward voltage; if you want to be precise you can look up the curve and make sure your voltage matches the current.

The specs provided by the seller appear to assume a nominal 0.05W/SMD which will not be achieved with those ballast resistors in the circuit. Maybe if you drove it at 30V, but the resistors would probably melt! Or perhaps the 67.2W is supposed to be the total input power including circuit losses. Either way the declared lumen figure is a joke, perhaps a maximum possible output from that number of SMDs but physically cannot be achieved with this tape. Given the total SMD power around 50W, you might get 5,000 lumens out of it, around 300 lm/ft (perhaps a few more if this is some sort of brilliant new LED), in short lengths. And this is a (relatively) reputable supplier. Buyer beware!

Note that this is still a fairly high power tape and you should probably mount it on some form of heat conductor for maximum life. Another note is that driving from both ends is really no different from cutting the tape in half, which is usually more convenient. Driving one input wire from each end is theoretically useful but actually means the whole tape runs at reduced output. Multiple short lengths is always best when practical. At 24V of even the cheapest tape you’d be hard-pressed to see (or measure) any brightness difference over a 4’ length.

gangstead
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Thanks lithopsian that’s all very useful. Basically the take away is don’t pay the SB-LED premium because their numbers are just as (not) reliable as anyone else’s. I’m kind of losing momentum on this project because it seems like such a crap shoot trying to get decent parts.

The only thing I can add is that the “2016” is the size of the LED. Surface mount components like resistors and capacitors are sized the same way. 2016 = .20” × .16”. I just double checked and it is actually inches. Regardless, like you said, it tells you nothing of the brightness or any other specs of the LED other than the footprint it takes on the tape.

gchart
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I’ve installed several sets of undercabinet LED lighting in various forms: flexible tape stuck to the wood, rigid PCB-mounted, rigid aluminum-mounted, and PCB-mounted in plastic housing. I strongly disliked the tape-to-wood install, the strips kept falling down and it just looked cheap. I liked all of the rigid products and being able to screw them into the wood of the cabinet provided some peace of mind.

A couple of those installs used LEDs from InspiredLed (who also sells on Amazon) – good products, middle-of-the-road prices. I’ve used their Pro Series and Designer Series. They’re all plug-n-play, no soldering. One nice perk about the Designer Series is you can get them in custom lengths (~1” increments) from 3” all the way to 60”. Makes a super-nice looking install and it goes really quick. And the folks there are great to work with. They’ve let me swap components in their kits, answered emails promptly… good stuff.

hank
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Each time I’ve had a light/switch circuit put in, I’ve made sure to include a spare conductor wire coiled up in the boxes for later
(that’s four-conductor wire, black-white-red-green, with the red for the second light later on)

I find I can get these: https://www.diodeled.com/fluid-view-12v-led-tape-light.html
in both white and amber, and they have “Duo” enclosures that will handle two striplights — side by side I’m thinking of using those where we use white light most of the time, but change to no-blue/low-blue light in the evenings after 8pm or so.

Lithopsian
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Don’t let me talk anyone out of using a premium supplier, or a cheap Asian import for that matter. Just consider carefully how important it is to get exactly what you ordered, have a reasonable chance of returning it if there are problems, and take a sanity check on the power and brightness. Strangely the only supplier I’ve seen offering remotely accurate lumen estimates was a bargain basement eBay seller from China, although they got the SMD number wrong.

That “2016 SMD” is still bugging me. Apparently from here , but can’t find the specs for the SMD itself. I did find some apparent light analysis screenshots, looks like they get the high CRI with a rather wide-bandwidth yellow phosphor and a very mild yellow notch filter. This is a premium product because of the number of tiny LEDs packed in, you can get high CRI tape with similar performance for a lot less.

Lithopsian
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I agree that the raw tape is ugly: the LEDs themselves are painfully bright, they change colour and brightness seen from an angle, and the tape is never 100% straight or flat. Only ever use it where it won’t be seen. The profiles are nice, act as a heat sink, and you can get diffuser covers, but can cost more than the tape.

You can successfully stick the plain tape even upside-down, but you need to clean the surface carefully, take great care sticking it down to avoid bumps and wrinkles, and make sure that the ends can’t peel off. Use a clip or glue particularly on the power supply end. The waterproof strips are heavier and might need some additional glue. High power strips can get hot and soften the glue. Works best on very smooth surfaces, no chance on anything textured without extra help like some hot-glue.