The Tao of Chinese LED Strip Lights

Did you buy the RGB strip or the white light strip?

Looking at the photo, there are three resistors per three LEDs on the RGB strip. Should be the same configuration with all three RED leds in series with a resistor, all three GREEN leds in series with a resistor, all three BLUE leds in series with a resistor.

Leave the resistors as-is or you are going to fry some LEDs.

I got the neutral white version. I just increase current until color change and then I decrease it…so everything is safe.

The only datasheet of a similar 5050led I found, showed that the parallel legs are one led with forward voltage of 3V or so.
I will try to wire the LEDs parallel and power them with a 7135…

Edit I tried the 3 inner led in every led they seem to work from 2.7-3.7V above that they get blue and then they fry…
I cut the LEDs in single and paralleled 3(6inner leds 3 fried) LEDs and powered them up with 0.4 A. I would be happy if I could do this without ruining the strip, than I would try some kind of 18650 powered lantern or so…

You should connect + from one side, and - from other side, otherwise you have huge voltage drop across the stripe (causing the under-spec current).
After doing that, adjust the voltage of power supply so that voltage across + and - lines in the MIDDLE of strip is exactly 12.0V.

I think it isn’t possible to use these strips in full power without additional wiring in either way connection. Increase voltage will lead to overdriving some LEDs…inconsistent brightness in either way.
Edit: I have thought about your tip and I will try this tomorrow, if I connect one connection to every side the resistance to every strip should be equal…that’s clever

I think I have measured the current for 3 LEDs incorrect…will do that tomorrow again.

As I can live with 1 m strips brightness at0.9A I will parallel 3 strips and glue them on a piece of aluminium and screw that underneath a shelf to enlighten my desk. That was the plan and still is. Also I have wrote fasttech a message to ask if they have additional info or tips regarding the 72W thing….
But it would really be fun if I could use some of the strips for battery application

My other parts dimmer and so on I ordered for this project on the same day as the strip but from DX are just departed, and this is just a partial shipment…DX is so slow…

I have somewhere a 12V 3A power supply laying around and I will test to power the strips with that tomorrow…

And yes they smell

Yup, it took some time to come up with this solution - but after I implemented it, each and every triplet (is that even a word?) of LEDs measures exactly 12V, no matter if I measure it on either of ends, in the middle, or in any other place.

By connecting the + to one end of the strip and the - to the other end, the LED voltages along the strip are fairly well equalized. Driving each end with + and - is even better. Diving long strips from one end only is bad. The LEDs at the far end are starved for current due to voltage drop along the strip.

Oh crap, how could I overlook a idea that’s so simple yet makes so much sense… :stuck_out_tongue:
Thanks for this, I’m going to re-wire a few LED strips I have around the house now.

So I have used some meters of this strip and it is ugly blue…okay for my worktable but a neutral tint would be better. The good thing is it has stopped stinking, after laying around outside off the bag and powering it up some hours it does only smell if you go nearer than 50mm.
We will see how long the sticky tape on the back lasts, as it gets hot about 55°C=130°F. One element needs 50mA, one meter has 20 elements(60 LEDs ) and pulls around 900mA.
I use 3 strips of 0.95m(57 LEDs ) in parallel powered with 11.9V and about 2.6A. I have them connected on each side.
They are far away from 72W like described from fasttech so i got 30% of the money back and they have removed them until they have cleared things with the suplier.

I found out what my problem was. Each of the pads needs to be soldered, three are negative one is positive.
So 3inner leds(one of each 5050) are in series with one resistor, and three of these groups are in parallel.

The problem that I found with those stinky, sticky epoxy-ish coated strips is that they soon die. It looks like the epoxy stuff traps heat and/or reacts the the LED surface. The end leds on each 16” strip of mine were fine, but all those in the middle died and were barely visible. This occurred after a couple of months of 24/7use.

I have cold white and RGB strips, waterproof, dunno what it is but even after 3 years? It’s still soft when I press it with a nail. It did not crack, nor discolor.
They did smell when new that’s for sure, but not once installed and in the open.

Work fine for 2 years now?

The only tiny discoloration is from the copper at the places where the copper traces for cutting the strips are.

I think they are the smaller type 3528 and around 2m length.

Mine are also still fine but I only use them a couple of hours a day and I glued them on a aluminium rod. They also stopped to stink.
I hate the bluish colour, If I had to do it again I would probably use some of the 12V LEDs, these have much nicer colour temp. So I have laying around about 1.5m without use…

New to the forum, just found this! I’m an amateur LED enthusiast that last year made a go at turning this knowledge in to products. I started with high quality cree stuff and hand assembling my own circuit boards but am ever intrigued by the cheap Chinese light strip product as it is super cost effective for $/lumen.

Yes. Tieing the back to the front will get you even voltage across. That is how super regulated power supplies work. You bring a wire from the far side back to a voltage input on the supply and it automatically adjusts so that it accounts for voltage drop over the wire. Voltage drop over distances will happen. I haven’t studied this on a lot of the strip light but will look in to. It is a real phenomenon but dont know how drastic it is in this case. Wiring up to the strip with 18ga or bigger will definitely help for higher current draws of your whole system because that will be a choke hold.

Things I’ve done before if there’s strips side by side is pull the plus and minus from strips nearby in the middle so that even if there is voltage drop its from the middle and not the ends so the light doesn’t look increasingly dim from left to right or top to bottom if you’re going in one end and out the other.

I’ve bought the eBay and DX stuff that doesn’t come as described or isn’t the same twice. Amazon has some cheap reels but I feel like that is blow out product and when they’re out they’re out and you never know how accurate their specs are.

I found a great Chinese vendor at a trade show that makes super high quality strip light (they only sell business to business). I’ve bought multiple samples from them and the quality has been super high and lumen output is very high. They provide light files and everything.

Anyways quality stuff is out there its just hard to know what is good or bad on a website. I would say if something doesn’t give you Volts, Amps, Lumens, and Color Temp then stay away. These are specifications every person making a LED product should know even if its theoretical from data sheets. A lot of strip light on websites if it does have lumens don’t tell you if that lumens is for the reel, per meter, per foot, per cut strip or what.

I like to look at total lumens when comparing products. It is the most simple and is the easiest to compare what you’re paying for. I believe some manufacturers use lux (lumen per square meter) ratings though for incandescent equivalents. Go to Home Depot’s website and look at a Cree A19 and Cree BR30. A19 is 800 lumens and 60W equivalent and the BR30 is 650 lumens and a 65W equivalent. How could it be less lumens but a higher equivalent? I use incandescent wattage x 15 lumens/watt and then compare to what my LED total lumens are.

I launched a kickstarter this month for a 12VDC light that uses 12v product from the vendor I spoke of earlier as the light engine and I corded it with a car plug. I’m making the housing. I am including a wall adapter for a car plug so you can use it indoors. Its 300 lumens in 11”. Really bright for tape light! Tape light that has to have a heat sink.

https://www.kickstarter.com/projects/1749518521/mount-anywhere-led

Anyways check it out or support the cause for one if you’re interested in seeing the tape light and how cool and finished a product you can make from it.

I’ve got some experience in this if you want to ask me questions.

[quote=lightvision1A19 is 800 lumens and 60W equivalent and the BR30 is 650 lumens and a 65W equivalent. How could it be less lumens but a higher equivalent? I use incandescent wattage x 15 lumens/watt and then compare to what my LED total lumens are.[/quote]

BR/PAR lights are reflector lights and you lose quite a bit of output there. LED equivalents don’t have the reflector losses but do have losses in their optics.

Also, a better number for USABLE incandescent output is 10 lumens/watt. Most decent LED bulbs deliver 50-60 lumens/watt once you get all the losses figured in… larger sized bulbs are usually more efficient than the smaller ones.

texaspyro, or anyone else willing to weigh in… I’m looking for recommendations for power supplies for these bad boys. I’ve got a 5m strip of 5630 WW leds that I’ll cut into appx. 4’ sections (75 emitters). These will be used outdoors (under canopies, so not super-exposed), so would like a tidy-ish box as opposed to a harvested PC power supply.

It seems like 1.25m wants 18 watts… does that number fit your experience? And wattage-wise, are the specs of transformers on ebay kinda like the chinese lumens problem? Should I shoot for a bit of headroom? These aren’t going to be in 24/7 service, but I really want them to run all night without failure.

You might look into using something like a regulated wall-wart or laptop supply. My dining room table (Replacing Lumiline light bulbs with LEDs) used 10 meters of strip and draws around 6 amps on high. I needed around 14 volts to overcome wiring losses and used an efficient 15V power supply adjusted down until the “bulbs” saw their rated 12V.

When driving longish pieces of strip you need to feed the “+” voltage into one end of the strip and the “-” into the other end. Otherwise the LEDs on one end will be overdriven and those on the other end will be starved for power.

I used a 12V power supply I bought from a shop which sells cheap electro parts, which they buy in large quantities. It’s a small black box like a laptop power supply and I mounted a DC socket on the strip to plug it in.
My strips are only one meter long and I fed them from both sides because even on this small distance I saw a to high voltage drop. Check post #20 for my current measuring.
It works but if I had to do it again I would do it like Tp recommended and tweak the max out of it.

There are tons of nice DCDC step down modules on ebay, one of this and a laptop power supply might work well.

Thanks for the info.

As a total side note, Werner, I suspect that the 72w number refers to the entire 5m string. Of course, finding accurate numbers on ali/ebay/ft/etc is ridiculously hard.

BTW, I was testing a strip while it was still on the reel… it melted the reel rather quickly.

That’s incorrect. Such driven strips have minimum of voltage in the center. So driving the strip from opposite sides allows to double LED strip length. No more.