This is more a general question on LEDs, not FastLED library.

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This is more a general question on LEDs, not FastLED library.
I installed a WS2812B LED Strip under my handrail in my loft area to provide some indirect lighting. I used 5V 60/M strips and it’s a total of 453 LEDs. This is my first time using LEDs for anything and I didn’t realize how bad the voltage dropped off with these. If using full brightness and set the LEDs to white, probably a meter into the strip I start seeing the color shift and by the end of the strip its only a dim red. I’m having to set the brightness to about 25 in order for these lights to look right. I only have power on one end and the only way to insert more power in will be to run wire along the back of the LED strip the entire distance. There’s just no other option for bringing power in and I’m not even sure if I have enough room for the additional wire. Would it be worth replacing the strip with a 12V strip? Are there any other options to keep power up?

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each led in a ws2812b uses 60ma (miliampere). It seems that your power supply is way belong this. Which power supply are you using?

First you need to feed them with enough power. then, depending on the lenght of the strip, you might need to feed it in different points of the strip.

sometimes it also helps to connect the ground to the end of the strip. check out this video at 4:20

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Power supply isn’t an issue, I have a 40amp power supply. Just too much resistance. I’m going to attempt running a couple 14-16 AWG wires along the strip to serve as a power bus and then attach every 1.5 meter or so.

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@Leo_Bettinelli - Not sure if you meant to attached a URL to a video?

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Hi @Kory_Kearney
Good idea to run heavy gage wires along the strips. Have a look at this to calculate the voltage drop that your planned mod would have…
http://www.calculator.net/voltage-drop-calculator.html
WS2812 data sheets specify operations with voltages down to 4.5Vdc. You can actually go below that but then correct operation is not a sure thing !

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Note that the strip itself has some ‘conductance’ and will of course improve any calculated voltage drop from that tool !!

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@JP_Roy - I had found a similar voltage drop calculator but wasn’t sure how to calculate the load current. My total current for all LEDs on full brightness displaying white would be just shy of 30 amps but doing this as a DC Power bus, I wouldn’t need full 30 amps at the tail end of the wire, probably just 3.5 or so if I were to insert power every couple meters. I suppose I could do several calculations to cover every time I insert power, the distance it is to that point and the distance remaining, current draw, resistance, and current left over… good point on the fact that the strip itself has some conductance which i wasn’t accounting for before…

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ey kory. there: https://www.youtube.com/watch?v=8fTzvx9IIsg

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Hi again @Kory_Kearney ,
My own experience shows that a WS2812b device actually draws only about 45 ma at full brightness white. However, I always use 60 ma per device in all my power calculations as that gives you a nice margin for PSU and wiring specs.
Very good point about the total current actually dropping each time you tap-in to your strip and you definitely need to account for that in your calculations…
With 453 LEDs, if you tap in after each 90 LEDS…
At LED 0 you have 450 X 60ma = 27 amps
but at the 1st tap (LED 90) you actually have 360 X 60ma = 21,6A etc… etc… so that first 1.5 meter only carries 21,6 Amps and that is not considering the strip so that would only give you an improved performance AND the actual draw will not be 60 ma but 45 ma !!!
If you can afford it… in available physical space, assembly hassle and $$$… always overdesign that power distribution !!!

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thanks @JP_Roy . This is my first time doing anything with these lights… and I guess now I know I need to plan for that on future projects. Even as it sits now with limited power, this FastLED library makes it easy to control the master brightness and while it isn’t super bright during the day time, when it gets dark, they are still plenty bright when set at 25%. I will still attempt to run the extra wire and take what it gives me… if I decide in the future it still isn’t what I want, maybe I’ll swap out for some 12V LEDs.

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what would be the benefit of using 12v led strip?

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The short version is that a 12-volt strip might work better. Here’s why:

  1. In a 12-volt strip each LED is still actually a 5-volt LED.

  2. There are little 5-volt-output voltage regulators all along the 12-volt strip taking in power from the 12-volt lines and supplying 5 volts to the LEDs.

  3. These voltage regulators will output a steady 5 volts for the LEDs as long as their input voltage is (say) 6.volts or more.

  4. So EVEN IF the voltage at the far end of the 12-volt power rails sags two volts to 10v, or sags four volts to 8v, or even sags six volts to 6v, that’s still enough the the voltage regulators to supply steady 5v to the LEDs.

Contrast this with a 5v strip: if the power at the far end of the 5v strip sags two volts (down to 3v), that’s just not enough to light the LEDs any more.

So I find that for long runs of LEDs, say more than 100, using 12-volt power rails is definitely a useful option.

The only other two alternatives that I can think of are: run a nice thick set of + and - wires along next to the LED strip, and ‘inject power’ into the LED strip every so often, or just drop the brightness until the voltage sag is tolerable – which you did!

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thanks mark for the information