I would like to buy 24V SK6812 (RGBW) LEDs (Link to product I’m referring to)
I see that the WLED Wiki has SK6812 as compatible BUT it says 5V in the second column. Does this mean it’s only compatible with 5V versions of the SK6812? I’d like to buy 24V so that I don’t have to inject.
Should be fine.
A little discussed “feature” of all the WS28xx,SK68xx,etc. strips - the data line is always 5V.
The higher voltage versions are about trying to drive more of the RGB(W) LED’s at the same current as the 5V versions. Using higher voltage can mean ~ 3 LED’s driven by the same current to get the same brightness. That’s all on the output side of the chip, the input side is the same TTL 5V signal for all of them.
A classic example is the SP511E controller many people are using. It takes 5-24VDC as an input and will drive a string directly. Internally it has 2 voltage converters, one 3.3V for the ESP8265 chip and one 5V for an on board Level Shifter driving whatever string you attach.
Thank you for the detailed and prompt response. I tried reading the datasheet to get a better understanding but alas the datasheet was a bit sparse and only referred to 5V. So am I correct in assuming that by buying the 24V version I will be able to run a longer length (more LEDs) without having to worry about injecting power mid way or at the end? Essentially my goal is to run 32m (112ft) of 60 leds/m without needing injection.
As far as data goes you’ll be fine, power is another story.
I have used a number of addressable pixel strings in both WS281x and SK681x(W) formats.
They have been predominately at lower densities than yours, typically 10leds/m.
I try and power my strips from the middle outward so that the drops for each string are split into two pieces that are each half of what the whole string would force.
For 5V strings, the worst case has been SK6812 RBGW.
A 5M string powered from the center needs ~3A of current and sees a drop of .5V at each end.
A 12V string (again 10leds/m) powered from the center, sees a drop of .35V at each end.
Given the lower drop of the 12V strings, I can safely run 10m 12V (2x5m pieces) strings powered at their central junction and see less than 1V drop at the ends.
All of this is highly dependent on the gauge of wire that interconnects the LED’s in a string. For my strings it tends to be 20AWG or sometimes 18AWG. Strips may do better (or worse) for higher densities. Unfortunately you won’t really know until you can try your product.
One technique I use often (and highly recommend) is to run a continuous “high voltage” bus in parallel with the main string and attach modular buck converters at your injection points. That lets you supply lower current over the bus line (due to the higher voltage) and drop it to the voltage the string needs at the injection points. I’ve done 600 LED’s over 30m using a 24V bus with 5V converters as needed.
I don’t see you getting away from some power injection over a run that long. At absolute minimum you’ll need some fairly heavy wire to try and transport the total current load. In the real world I settled on a reasonably small wire (2C-18AWG stranded is available in some really small jacket sizes) with lower voltage drops at the current I need.
Note that my bus does indeed experience voltage drops as well, but I’m much less worried about a 5V drop on a 24V line when my end goal is to get through a 5V converter. The downside is you end up using a larger power supply than you might otherwise need but you never worry about voltage drops at the string.
Thanks again for the detailed response. I understand what you’re saying, and the 24V bus line makes sense and I thought about doing something similar. Problem is that I’m planning on running it in an aluminum channel that won’t have much room for a bus line without that bus line potentially partially blocking the LEDs. I guess I’ll have to see how thin of a wire I can get away with and how much space I have in my channel as well as the orientation.
So if I’m going to have to inject power anyways or run a bus line, is it worth it to go for 24V strips or should I stick to 5V?
Also, you said you’ve done 10LEDS/m, ideally I would want 30 and not the 60 that’s offered in the link I provided but I’m having trouble finding too many options that are not from Aliexpress (I don’t want to have to wait for over a month to get these). Any recommendations for sites where I can buy LED strips with a lower LED count?