Hey all, A few months ago, when I was hooking up my first pixels, I spent a decent amount of time trying to understand the voltage drop of 5V WS2811 pixel strings. The reason is that, for the first decoration element I wanted to use them in, I was pretty sure I was going to need 20-25cm (8-10") pixel spacing. I had ordered some 5V 25cm (10") WS2811 pixels from Ray and was seeing horrible performance. My first instinct is to try and understand what the @#$% is going on and that resulted in the following thread: http://auschristmaslighting.com/forums/index.php/topic,4155.0.html So, I ended up deciding that the higher pixel spacing just wasn't gonna cut it (didn't like the idea of injecting power after 35-40 pixels) and I ordered a bunch of strings for my twelve trees with the standard 10cm (4") pixel spacing. When I placed that second order, I also ordered several different spacings so that I could make some more voltage and current measurements. I ordered these lights: http://www.aliexpress.com/store/product/50pcs-DC5V-input-WS2811-LED-pixel-light-with-all-black-wire-IP68-rated/701799_1032448178.html with the following spacings between pixels: 50mm (2"), 75mm (3"), 100mm (4"), 150mm (6") First off, I should mention that, in a very repeatable fashion, the pixel spacings are all off by 25mm. No joke. While it doesn't matter for the current application (wrapping trees), it would matter if one was attempting to grid something out. I have another application coming down the line where I pretty much want 75mm pixel spacing, so I guess I will have to order 50mm to get it... Just like in the first link above, I did all testing with a standard 5V power supply and my P12R controller. I measured voltage at the beginning and end of 50 pixels with the above spacings and I also measured current. Here are the results: [attachimg=1] I included the pixel spacing I asked for as well as the actual pixel spacing. The top and bottom tables are identical, but the one is in "I'm from the U.S." units and the other is in "I'm not from the U.S." units. You will see voltage at pixel #1 and pixel #50 for white, red, green, and blue, as well as current for white, red, green, and blue. Important take-aways are: Although voltage at pixel #1 actually increases for higher pixel spacing and longer pixel strings, voltage at pixel #50 decreases with higher pixel spacing and hence longer pixel strings. Current draw decreases across the board as pixel spacing and pixel string length increase, inevitably due to the fact that there is higher voltage drop through the wire and less available to the resistors associated with the pixels. The data seems to show that the voltages at pixel 50 are near or in the range of the activation voltages of the blue and green portion of the LED but only the really high pixel spacing is below 3.0V. I don't know if it was my brain telling my eye what to see, but I did notice more pinkish reddish color when in white mode for those strings... I suppose I could get my wife to help and do a blinded random test... Anyhoo, just some more data to throw into the pool of useful data around here. 5V? Higher pixel spacing? Definitely going to need to inject power after 35-40 pixels instead of 50... but maybe most folks already know that?! Thanks for looking.