Noob needing help with first big project

Questions
1

First and foremost, I have little knowledge when it comes to leds. I have already done a small project where I removed regular lights from my Christmas tree and replaced them with led bulbs (forgot from the top of my head which ones exactly). I used a quinled dig quad and was able to calculate the appropriate power supply needed and the amount of power injections needed as well for a successful project.

That being said, I bought sk6812 5v led strips (30 per meter) and would like to install them in my roof as Christmas lights and I am planning to use buck converters to use a 24v power supply for wiring reasons. I need to buy the buck converters, wiring, power supply and the board to control them (planning on getting the quinled big octa board with a power board (which power board is going to depend on how many power injections I’m going to need for the entire project. So, I need to pretty much buy the rest of the supplies. Even though I have a pretty good idea on how to wire and install the project, I have so many questions/doubts considering I’ve never used buck converters.

So far, I have calculated how much power I am going to need and the necessary power injection points I am going to need for the 5v leds.

My first question is if my calculations are correct? Can someone please check my math before I move forward

Here are my calculations using the info on the BTF website:

  • 1m = 9w
  • 5m = 9w * 5 = 45w
  • 45w / 5v = 9 Amps per strip

My next question:
That means that in 4 strips (20 meters of 30 leds per strip = 600 total), I would need 36 Amps. Quindor in his YouTube channel uses the rules of 4 amps at the front and end, and 8 amps for the middle injections. Is this a general rule of thumb or do I have to calculate the amps for MY setup?

If the Amps needed per injection are the same as the video, that would mean that even if adding power injection in each end, I would end up with 32 Amps total where I need 36 Amps so I assume something is wrong with my calculations. Quindor does have a chart (real-world LED power usage sheet) where 5 meters uses 33.9w but for 60 leds per meter (again, mine are 30 per meter). He also uses his chart to calculate the watts needed in his 5v scenario. I don’t have the tools like he does to measure the real time usage on mine.

I will be posting more questions/doubts once people start answering my post. Thanks in advance!!!

2

hi @mreyna16 the Watts are only if you run WHITE at full brightness
you can run in the dark 512Nodes at 500mA
and they look great on a UNO R3 Board ESP8266 i did so

3

Thanks for the reply, I think he mentioned that he used those values in his chart because they were the highest and was considering those values for worse case scenario. Those weren’t the exact words he chose but something along those lines.

Like I mentioned before, I would like to use 24v power with buck converters. That would mean the power injection points would stay the same but the thickness of the wires would be calculated using the 24v power right?

4

Another question, if my roof has 3 sections (middle - highest section, and two side sections) and I want to use the same color and flashing sequence as if its one straight line, would it be a problem the length of wire used between each section? Roughly it would be about 10 to 15 ft between the top and sides

5

When using a 24V backbone, I find the simplest way to do the calculations is via the Wattage you need for each section/strip/project, etc.

Quindor’s calcs are often based on 5V strings so in your case, a buck converter (BC) becomes a 5V “power supply” with very short power wires to the strip. With that in mind, you can often treat that injection as supplying 2 strips to the “left and right” of the BC point. That also means you must grade your BC’s for that 2 strip maximum current.

In general, it’s a good idea to take the mfg specs on BC’s with a few grains of salt. I’m usually skeptical of maximum rated currents, I’d treat 10A ratings as 7.5A continuous and plan your injection points accordingly. Better to be a little cautious, although a test on the ground with an example of your expected setup will give you some confidence in your calcs.

As far as the data line questions, WLED will present your setup as one long string that you can split and/or manage in software. The physical data runs you’re suggesting are probably OK as far as distance goes. If the connections between the 3 sections will be an issue to get to in the long run, it might be worth considering the Long Data line solutions to ensure reliability.