Power injecting is simply running a new wire from a power supply and connecting it to your light string somewhere down the line from your first RGB pixel.
12v RGB lights can safely power at least 100 lights before starting to notice a drop in the brightness/color of the RGB lights. This is most noticeable if the last pixel in a series is close to the first pixel from the same series. For example, my snowflakes. The largest snowflake has 216 RGB lights in it and the last pixel is close to the first (starting) pixel. If I only powered the 1st pixel, the last pixel would be dim, completely off, or flashing random colors. I solved this voltage drop issue by adding additional power to the last pixel. This way 12V power is coming from both ends of the string of 216 lights. The sleight dimness that occurs in the middle of the string around pixel 108 is non-noticeable since the same dimness is at 109 and slowly builds back up by pixel 216 (where I power injected).
This is basically the diagram I followed when power injecting my craziest light string. The IMPORTANT thing to remember is when adding a second or additional power supplies, DON'T CONNECT the positive 12V wires between the two power supplies. In the diagram below I highlighted the area when the 12V power from the 1st supply IS NOT continuing on... just the data wire and the ground wire. The ground wires are OK for connecting the additional power suppplies to. Also, I learned about adding in a fuse holder on the positive wire. Power injecting needs a fuse to protect the positive wire and in turn, your lights, should a power surge occur. They recommended these being close to the power supply. OR you can bypass them all together by using a power distribution board that HAS fuses installed in them to protect the wire. (I learned about the power distribution boards too late, and ended up using the fuse holders.)
Here is my craziest string of lights on my house as of 2017.
The red wire is the 12V positive line and the black wire is the ground wire.
Since the first vertical string of lights is about 38 feet away from the controller, I had to add some null pixels to the line to duplicate and pass the data information on down the wire line. A null pixel is just a normal RGB light soldered on the main wire. I've read you can go about 15-20 feet before needing null pixels, but I ended up needing a null pixel every 10 feet on my 18 gauge wires. On the e682 webpage, I simply typed in how main null pixels are on the line before the 1st pixel in my long light string. In this example it was 3. The controller then ignores these null pixels and won't light them up. I soldered on a null pixel like this and shrink tubed it up after squeezing in plenty of hot glue to help waterproof it.
The main controller and power supply #1 feed the first vertical light line on my house. Then the complex snowflakes are connected making sure to leave off the positive 12V wire leading into the 1st pixel of the left-most snowflake. Power supply #2 is located below the snowflakes and allows me to run shorter lengths of wire for power injecting. I use 2 lines and inject power in 2 separate locations. By injecting power at the start of the 1st snowflake, I needed to add power on the last pixel of the same 1st snowflake. Since electricity runs like water, it gives additional power at the end of the first snowflake AND the start of the next snowflake! The second power injecting line gives power to the last pixel of the large middle snowflake and again at the last pixel of the small right snowflake. Same as before, the power runs both ways and also powers the final vertical set of lights on the house.
I chose to do this because in order to power inject the snowflakes from Power Supply #1, I'd have to run super long lengths of power injecting wire all the way to the snowflakes. By adding in Power Supply #2 here, I saved myself about 140 feet of power injecting wire! Also, the longer the power injecting wire runs are, larger gauge (and more expensive) wire is needed. This way, I could keep using the 18 gauge wire I've been using to power inject.
Asking about this power injecting question on the doityourselfchristmas forums, I was directed to this AWESOME link for calculating power injection. It allows you to enter the gauge of wire you use, how long you plan it to be, voltage, watts, and where you plan to power inject in your system! Below is the graph that was outputted by my setup above. The tall middle spike is the middle of my largest snowflake where the voltage drop is estimated to be about a 10% drop, but still green for plenty of power.
That's about it! So in hindsight, 12v pixels let you run over 100 lights before needing power injection... and if you use the cheaper 5v pixels, you need to power inject about every 50 lights. I did not want to do that, so 12v is ALL I USE. I use 5 amp mini fuses inside my fuse holders to protect the wires.
Hi.... I may be making this harder than I need to. The plan is to use one port on the f16 for each arch. So total of 4 ports. I had thought since I had one string per section that I would inject power before each string. But if I understand better now, I can just get a separate PS and run it to the "far" end of each arch, tie into the falcon PS ground and all should be ok? That sounds much better than what I thought needed to be done. Any idea what size the PS should be for injection? Also, as far as weatherproof connections, could I just solder a pigtail I have to the 12V from the PS and another to the end of my pixel string and just use that for my connection? Thanks again for your help. This issue has been one that it seems I'm making it harder than it has to be.
https://www.7pcb.com