Electronic – Powering 17 meters of RGB LED strip – Worried about voltage drop and wire size

led stripvoltage

I'm modifying an IKEA Ramvik coffee table by mounting lengths of individually addressable RGB LED strip under the glass controlled by a Raspberry Pi. The LED strip is pretty standard; running at 5v with 32 RGB LEDs per meter, each one has an WS2801 which talk to each other via SPI. It's identical to this one: https://www.sparkfun.com/products/11272

In total there's going to be just under 17m of strip: 16 rows split into 106cm sections. I'm going to be wiring the rows up snake style and dual feeding to keep brightness consistent across the array.

At full brightness, with all LEDs on, each row of strip will draw just under 2 amps, multiplied by my 16 rows, that's 32 amps in total. With this much ampage running I'm concerned I'm going to need some hefty wires to handle the load without dropping voltage. Unfortunately the design of the table means that there's only around 3mm space underneath the glass so the diameter of the wire is important.

The 5v power supply is going to be mounted inside the table, around 0.5m from the start of the LED strips. I've been running some calculations which says even if I use 16awg wire I'm still going to see a drop of ~0.5v.

Is there any way I can negate this or do something to prevent it?

Best Answer

I'm going to be wiring the rows up snake style and dual feeding to keep brightness consistent across the array.

If Dual Feeding is what I think it means, you already know what to do.

Feed the 5v to each 106cm section individually or in pairs. Don't chain the power through the entire 17m length. Sure, this means 8 or 16 sets of 5v and Gnd cables, but with each only carrying 2A or 4A over a small length, heat/current/resistance issues go away. Same reason you only see 18 AWG wire in ATX Power Supplies. Instead of a single 10AWG 12v Cable, it uses 8 or 12 18AWG wires to carry the same current.

You would keep the data cable the same. Just make sure to tie the grounds together.

Actually, pretty much how the datasheet for the Sparkfun item you linked to already has it, for a snake layout. enter image description here

For 1M strips (106cm = 1.06M) the voltage drop would be insignificant.

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