I know there probably many variables to consider here, but I installed 2 16' strips of LED in a crown molding in a theater room. I noticed right away that the brightness dimmed gradually, with the LEDs closest to the power supply considerably brighter than the ones nearer the end. Is this normal? I have another set on my desk to replace those, because homeowner wanted a warmer color. They are behaving the same way. We definitely have enough current. The power supply I have now is actually a magnetic LV dimming module/power supply. The one at the home now is just your standard AC/DC wall wart.

Is this a function of the strips themselves? Is it considered "normal"? I have some LED christmas light strings that do not exhibit this behavior. We just finished a theater room at an old folks home where the electricians installed some LED rope lighting across the 3 risers and they do not exhibit this behavior. So there has to be something with the strips we have been using, right?

Any best practices, pointers, product recommendations? The ones on my desk are from LEDJump, the dimming module from Hitlights, where the original strips also came from. My plan is to run a 2 conductor wire from the power supply all the way around and power the second strip from the other end. Hopefully this will make thing a bit more even at least.

Your cure is exactly what I was going to suggest. You might even connect that added pair to the middle of each run if you can. Your wire will be a larger gauge than the copper in the tape. You know this will solve the problem, which is a hint as to what's going on.

It sounds like you're running the string a longer distance than it is designed to go as a single piece. Think about it -- all the current of the LEDs at the far end goes through the small copper traces of the entire length of the tape. That copper has resistance and the copper feeding the far LEDs is the WHOLE strip, so the highest resistance. It makes sense that there's some length where the voltage drop across the copper will make the LEDs visibly dimmer.

Contact the manufacturer and find out what their maximum run length is, and be ready to ask them to how to cure this if you're within their spec.

Hi,

There is also the possibility the some "brands" of these products have heavier copper traces which would reduce the voltage loss.

Were did you get your product?

I've done a handful of locations and I have always fed power to each strip separately just because it seemed like a good idea. I did NOT check with the manufacture to see if they had a spec for this.

Frederick

Most of us would not check with the manufacturer until we had a problem. That's just human nature and technician nature. We figure we know what we're doing until it's proven otherwise!

Thanks for the input.

The first strips were from HitLights. Their Luma5 strips. The manual states that you can connect 2 strips without any additional parts, but going beyond that, they sell an amplifier that goes between, with separate power inputs. Not sure what difference this is vs. my idea of just running a wire from the power supply and powering the 2nd strip directly.

The second set is from LEDJump and they have no instructions really at all. But the principles stand that are mentioned in HitLights documentation. DC voltage drop is not your friend. :)

Easy explanation. Easy solution.

A quick glance at one product on the LEDjump site has a doc that says they are "linkable" and a wiring diagram showing each strip fed separately.

Go figure.

Frederick

Go to Home Depot and get some Armacost LED strip lights. [Link: homedepot.com]

If they don't work, return them! I'm using about 20' of these in my kitchen and I don't notice any difference in brightness.


Eric

20" or 20' ?
Big difference between 20 inches or 20 feet.

That is funny ^

Rule of Thumb with LED Strip Lights:
12 V: Power insertion every 5 meters
24 V: Power Insertion every 10 Meters
RGB 12 V: Power Insertion 5 meters thru RGB Coupler
RGB 24 V: Power Insertion 10 meters thru RGB Coupler

Really think you will get an answer calling Xo Chang Lo Duckwang being an ebay seller. Go with Ernie. Rewire it.

Well, perhaps, but "power insertion" can simply be the same pair of wires that are connected at one end, also connected at the other end and somewhere in between, so the lower resistance of the feed wire keeps the LEDs from being of different brightnesses.

By the way, you can get the original wiring to deliver a more uniform light level if you reduce the light level of the LEDs. Lowering the light level is like adding resistance in series with the light strips, in which case the effects of the resistance of the copper in the light strip is swamped out by the overall resistance.

Sorry, I edited my typo.

Eric

Simple. Connect your power to both ends.