I am looking to create an addressable RGB LED strip circuit with my NodeMCU v3 Wi-Fi. I am looking at a strip of 150 RGB LEDs, 5 meters long, so 30 LED/m. But I am only going to use about 50 LEDs for the backlight on my desk. My understanding is that if each RGB LED pulls 60 mA on full white, and I'm running 50 LEDs, then I will need at least 60 mA x 50 LEDs = 3000 ms (3 A) of power to sufficiently light all of them. I am thinking about upgrading this in the future, and so I am thinking about going with a 5V 10A power supply. Am I okay to go with a 5 V 10 A power supply? Or will this be too much current for the system.
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In your case I would use ledstrips with SPI protocol (like APA102). Using SPI, you can have your resources free (not having to bit bang), transmission speed is higher (no fixed delay) and you can allow more time for calculating the next pixel, so you don't have to store them all in memory. Also, the nodeMCU may not always be "atomic" or do every instruction in order (and has to yield every now and then) so the hard timed bit banging of neopixels may not be glitch free/doesn't seem correct for this application.– PaulDec 7, 2018 at 0:43
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I generally double my current needs when looking for supplies and wiring. So if you think your load is 3A then I would get a 6A power supply. I'm thinking like @Paul. You may have problems generating the timing of older addressable LEDs as the ESP8266 is also concerned with WiFi communications. The more complex the processor's responsibilities, the worse the real time response. That's why it's difficult to drive these LEDs from a Raspberry Pi.– st2000Dec 7, 2018 at 1:17
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the current rating of a power supply is how much current you can draw before the power supply overloads ..... the current rating is not how much current is forced into a connected load .... think about 100W light bulb compared to 5W nightlight .... both connected to a 15A 110V AC circuit ..... 100W bulb draws almost 1A .... 5W bulb draws about 50mA .... neither one has 15A forced through it– jsotolaDec 7, 2018 at 2:31
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1 Answer
Each will only draw as much current as they normally would from a 5 volt supply. If you had a 5 volt 100 amp supply they still would not draw any more.
The amount of excess current a power supply can deliver doesn't change what the load will take from that supply.
For example, if you had a 5 volt supply with a 1 ohm resistor as a load the current would be 5 amps. 5 volts / 1 ohm = 5 amps. And if you had a 5 volt 10 amp supply the current would still be 5 amps. Same with a 20 amp supply. As long as the voltage is the same, going up in current capacity is safe.
(LEDs are not resistors but with this application it is much the same)
When you do wire up the LED strips make sure you are using thick enough wires.
