I have a BTF Power supply DC 5V10A 50W. My initial plan was, if possible, to connect these three strips together to have a continuous pattern of christmas lights across the front of my house. I now see that the power supply won’t sufficiently push two strips at full brightness, I need to find out the wattage each strip takes up at full brightness. https://www.amazon.com/gp/product/B01D8FM71S/ref=ppx_yo_dt_b_asin_title_o05_s02?ie=UTF8&psc=1
Is there a resource that can I can refer to for power requirements of these and other various LED strips? I’m guessing I will need to purchase one of the larger power supplies (such as this one: https://www.amazon.com/BTF-LIGHTING-Aluminum-WS2812B-LED8806-Modules/dp/B01D8FLYW6?ref_=ast_sto_dp ) but (1) I need to figure out what wattage I need, and (2) What’s the most amount of wattage/LED length I can safely run without too much heat or blowing the LEDs, and (3) do these power supplies come with a plug?
I was also surprised to see that when I disconnected the power connectors in between two strips, they continued to work normally. So, the power doesn’t need to be connected to each other, but I’ve seen diagrams (which I cannot find now) showing voltage being connected/added at various intervals between the strips. How does that work?
Answers most of your questions and more so, shows you how to figure out the rest on a case by case basis, since it varies depending on type of led, wire used, power supply used, brightness, etc.
As for why the above works when disconnected, that’s not the right way to add power. Those connections are redundant, power is flowing on the main connector still connected. Those are meant to inject power from the power supply again, to avoid wire length voltage loss. Documented in the above links too.
To add to the helpful info from Scruffynerf, a commonly used rule of thumb is to assume that each pixel consumes 60mA at full white brightness, and a third of that in typical use. They do run really hot when run at full power, all-white. I don’t think of a specific wattage they will burn out at as much as just knowing that running them all white at full power will shorten their life.
So, if you want to be able to run everything full white for a few seconds, each strip of 300 LEDs would be consuming 300 * 0.06A = 18A. At 5V, that’s 90W.
There’s a couple scenarios where you might choose a less powerful supply than the max rated, but you do risk making a mistake that’s frustrating. One is you can size the supply for typical max current draw, which is 1/3 of absolute max; in that case you might choose a 6A/30W supply and be really careful to never livecode full-white (I’ve definitely made weird mistakes*). That’s part of the reason your 10A supply is working for two strips: it’s just not being maxed out yet. Another way is to set Pixelblaze’s total brightness limit in the Settings page conservatively, and perhaps use an ammeter to measure actual current usage.
You also asked if those power supplies typically come with a plug. In my experience, no.
* A few months ago I ran some code that contains math that’s deliberately chaotic (the three body problem). I had hacked on it for hours and it was visually chaotic as expected. I left it running overnight and found it the next morning in a state I had never seen where it had overflowed several variables and eventually turned all pixels bright white! I had secured the power leads with hot glue on the back. Enjoy:
So, a 300W power supply isn’t much more expensive than the smaller boxes. Not that I intend to run all-white, but if I did, that would be 270W. Assuming it will only produce what’s needed, is there any drawback to getting too powerful a power supply?
Also, how would you recommend building the power cord for this power supply? Or do they sell them on Amazon? [EDIT] Found the power cord for the Alitove model.
@Mebejedi,
No harm in oversizing the power supply a little. Of course you can get one that is large enough that it could put out a serious level of current if shorted, but it’s generally better to have an overpowered supply rather than underpowered when it comes to safety. Some of the cheap ones don’t like being overdrawn and get hot, drop voltage, and/or fail.
Adding an inline fuse from your power supply to the LEDs is a good idea. Most good power supplies have short circuit protection, but very high power supplies may not trip if the short is at the end of a long run of resistive wire.
Taking your example of a 300W power supply, which can put out 60A at 5V. A resistance as much as 83 milliohms (0.083 ohms) could draw 60A and not trip the supply’s protection circuit. If you plan on using much less, a fuse can help protect from shorts becoming a fire hazard.
For wiring, I like to consult this wire chart:
Take into account how long your wire will run for (counting both directions!) find the current you plan to run in the list, then check the resistance at the length you’ll have. Smaller wire will have more resistance and drop voltage over longer runs.
You’ll want to inject power into the start of the first strip, and at each joined segment thereafter. The strips themselves won’t carry enough current for later strips at full power, and will generally have more resistance which causes power loss and heat than the wire you’ll use.
OK, I’ve got 3 strands, a 300W power supply, and some boosters. My next question is this: Each strand has the data connector and pos/neg at both ends. If I put a booster between two strands, does power only go in one direction (Arrow A), or does it provide power in both directions (B)? If (B), then can I put a booster at the end of the strands?
And I’m assuming I should cap off any unused power lines, correct?
Hey @Mebejedi! In your diagram, power supply 2 transmits power both ways, IE to the second and third strip.
By “booster”, I think you are referring to “data boosters”, AKA signal amplifiers AKA null pixels (and not some kind of power booster product); when we want to re-boost the voltage I usually just call that as power injection.
I’ve never used the data booster things, but I think the concept is that they take degraded 5V data and restore it to a cleaner 5V digital signal.
Since apparently it’s recommended to use them every 10M, I assume you’re thinking of putting the booser between strands 2 and 3, where the A and B is labeled. In this case, although power is flowing both directions, the dirtiest signal is at the end of strand 2, and it’s clean again on the DIN side of strand 3. This should probably work. The data booster itself would be powered at the injection point in your diagram and consumes very little power. In your setup, if you were boosting signal between strands 1 and 2, you’d power the booster by tying its power-in side to either strand, but NOT both.
Therefore, a data booster at the end of a run of strands doesn’t do anything (but power injection is common at the end of a run).
I would insulate any power lines that have exposed metal conductor. If it’s pre-stripped injection wires, yeah, snip them or use electrical tape. If it’s female barrel connector or female JST-SM I typically leave them exposed. On most power supplies, the terminal block screws are well isolated and don’t need too much extra protection.
Sorry, yes. That’s what I meant…power injection. And it does look like it goes both ways.
Unfortunately, I have intermittent problems with my Pixelblaze losing its wifi settings, and it won’t switch back over to my home network. Kind of annoying.
That’s strange. You don’t have an external button wired up, do you? What firmware revision is it running? I seem to recall more WiFi setup issues on older firmware, but for the most part if I set it to join a network it stays on it. Now, glitching when the WiFi is weak - that’s a much more common problem for me.
And I noticed when I trusted them against each other, the orange light on the PB would start flashing and it would connect. Some other threads in here talked about how a poor power supply or connection could affect the wifi, so I guess that was it.
Now I have another question: what’s a good way to mount or cover this power supply for outdoor wiring? Like on the backside of my eaves?
I’ll probably have the PB and first power supply on the left side of the house, and try to insert a power injector at points B and C. Is there anything I should plan for or be aware of?
Hi @Mebejedi,
One thing I see with your power injection setup here:
I’ve added power quality gradients, basically distance from power. Parts of the strip farther away from a solid power source may have lower voltages than those close to power, which is caused by voltage drop. Voltage drop is caused by resistance, and will change with current draw.
It’s possible for them to swing differently than each other, causing issues with data, and glitches, especially at higher current setups or with longer runs.
When joining 2 power zones, it’s best to inject power to the end and start pixel so they are both near their respective 5V power supply levels.
That also applies to Pixelblaze itself, you don’t want to power it at the far end of a strip away from the power source.
Thats not to say you will have data issues, but its worth testing before you commit to an install.
Also, keep in mind if you have the same power supply, you can keep the V+ lines connected. It may be easier to run wire in parallel with your strips and tap in every strip or two.
This is my first year doing this stuff too, but I’m trying some somewhat generously sized outdoor waterproof boxes with adapter plates for my power supplies. I’m ordering them from HolidayCoro.com; this is my first time using them so no record one way or the other for you yet. I’m using their HC-2500 box with base plate predrilled for Meanwell LRS-350W series (up to 4 PS with a tight fit). I’m doing this because I want to put PB and peripherals (e.g. relays / MOSFETs) in the box. Other people will just wire directly to a waterproof supple like the Meanwell LPV/HLG series or popular budget waterproof supplies.
Regarding:
For power injection techniques, there seem to be quite a few. If you don’t mind using Facebook ( ) the LEDs Are Awesome group has many posts about different techniques (like this one).
A few ways I’ve done this: zip tie large gauge copper wire to the back (you should size up by 2 AWG if using the budget copper-clad aluminum “CCA”). Look for some videos on a technique called “window stripping electrical wire” to solder tap in with minimal extra width, or get a quick automatic wire stripper with a strip length stop for speed and consistency and use Wago 221s. If you window strip, don’t forget planning for your heat shrink on the correct side (or use electrical tape).
So, I was actually thinking of wiring my lights like the top diagram with my 300W power supply, and then was lucky enough to run across this picture that demonstrated it.
My question is this: Could I also do it like the bottom diagram with the PB? Or would this require the expansion board as well?
The bottom diagram is pretty much what the expansion board is for. Do be thoughtful about current, though, as that diagram seems more appropriate to some of the driver boards that are meant for larger power distribution.
For several projects I have wired both power and data in a star pattern using the output expanders, but if using over 150 pixels total with the normal expander (750 on the Pro), make sure +5V and GND power is separately delivered through appropriate size wire, not through the expander.
For your outdoor lights, How far from your LEDs is your power supply and PB? I’m debating if I should mount those inside my garage, and run about 10ft lines to the strip.
(FWIW, tomorrow, I’ll be running 25+ feet of data line from the expansion board in my main control box to the upstairs balcony roofline. The lights are up and that section has its own power supply, so it’s just data and common ground. I’ve got several things to try, from shielded wire to a fake null pixel mid-run. Will post results after the experiment.)
) the LEDs Are Awesome group has many posts about different techniques (
