LED Strip (ws2812b) and Power supply question?


I have just flashed WLED onto a NodeMCU and connected this 5M LED strip to it via usb cable and apple usb wall charger (Output = 5V 1A).

Everywhere i have read online and the software itself says that i need a 9A power supply and that i should power the strip every 30 LED’s (which is every 1 meter). I live in UK and even if these are US (110V) calculations then i would still need more than 4.5A!

But it seems to me to be working fine for me??? any ideas? am i missing something?

The amps are calculated at 5v so the 230/110v doesn’t come into it.

It may be at full white brightness it might not cope or not be very bright. Could date the charger if it overloads it for prolonged periods.

Al ok - that makes sense.

I don’t think they could get brighter - they don’t seem to be working at a difficiency!

a 2A phone charger will quite happily power a node with 70 pixels. :slight_smile:

Sorry, I don’t understand what this means

its not so much about the length of the LED strip, its more about how many lights (pixels) it has.
i can confirm a 2A USB mobile phone charger puts out enough power to run a 70 LED strip and a node MCU.
have you checked out dr ZZZ 's youtube channel? some great wled info on there. :slight_smile:


But look at this?!

60 milliamps per LED (pixel) is the theoretical max at full RGB brightness. In reality, they use less than that. That’s why a 5VDC/2A phone charger may be able to support a 2m or 70 LED strip, but the output is limited to 2A at 5VDC and you run the risk of burning out the charger. However, don’t get total current draw and the amperage output of the power supply confused with voltage drop over a long distance. the reason it is recommended to inject power every meter or so is due to voltage drop on the 5V rail. measure the voltage after 1m, 2m, etc and you’ll see the 5V rail can no longer supply 5V. The LEDs are still attempting to do full brightness, but the 5V rail cannot support it therefore you get color shift and white starts to look more yellow and dim the longer you go.

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In addition to the already good advice given here I’ll toss a couple more at you.
Most of the time you want to install a capacitor at the point where your power is injected and also a resistor between your nodemcu and led strip on the data line. I don’t have references for you now, but something to keep in mind.

Also just fyi they make 12volt versions of these. Higher voltage means lower amps and 12 volt supplies are easy enough to find as well.
Have fun!

To expand upon what @danbutter said, a 1000uF/6.3V capacitor at the beginning of the LED strip between 5V and GND is a good practice to reduce the likelihood the sudden inrush of current will burn out the first LED chip thus preventing the rest of the strip from lighting. a 470 ohm resistor between the micro-controller and the first LED on the data line isn’t as important, but still good practice to prevent spikes on the data line from killing the first LED. Additionally, if you plan to place the LEDs in a different location from where the micro-controller will be or the LEDs are powered by direct 5V, you may need a logic level-shifter to take the 3.3V output signal of the micro-controller to the required 5V data in signal the LED is expecting. I’ve be able to get away without a logic level-shifter because the LEDs are connected directly to the micro-controller (less than 6 inches) and 3.3V is just barely on the edge of acceptable signal level for a binary 1 or “on” in the data stream.

The 12V version (WS2815) also has redundant or backup data lines in the off chance an LED anywhere in the strip dies, data is still transmitted to the rest.
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My strip shifts to the red on voltage drop. Running some red/black siliconed wire is on my to do list to resolve it :frowning:

End voltage is around 3.8V