Electronic – Powering 20 m LED strips

led strippower

I'm going to be powering some 20 m of LED strips at 24 V. After testing the strips, I can see that this will draw about 6 A.

Of course when inserting power from one side the voltage drop across the strip is large enough to make a significant difference to the brightness of the LEDs towards the end of the strip.

I would like to insert power from both sides of the strip, like shown below where I have modelled to resistance between across the power lines.

My concern in that the two 24 V lines might somehow compete with each other, having some unwanted power loss between them.

My question is whether this is a genuine concern or not? Would it be preferable to cut the 24 V line towards the middle of the strip?

Schematic

simulate this circuit – Schematic created using CircuitLab

Edit: I think I was a bit ambiguous. To be clear, I will be using a single power supply, inserting power at both ends (not sure if that makes a difference).

Best Answer

You don't need two power supplies. One is enough. Just connect the positive wire to one side of the strip and the negative to the other. Then you will have equal voltage at each LED group and this will ensure equal brightness of all LEDs.

schematic

simulate this circuit – Schematic created using CircuitLab

Using two separate power supplies has some drawbacks:

  • In the middle of the strip voltage will be lower than both ends. LEDs in the middle will shine less than LEDs at both ends.
  • One of the supplies may fail and not be noticed for long time, until someone sees the difference from one end to the other.
  • Two power supplies almost always are more expensive and installing mains supply (230VAC/115VAC) connection leads to additional costs.

Update: When current through the strip is higher that the strip could handle safe, you need to cut the strip to pieces and power each piece separately. However the cut pieces can also be powered as I suggest above to ensure equal voltages and brightness.

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