Electronic – Serial chaining of LED strips

currentledled strip

I need to confirm / refute my assumption about current in LED strips. I know they are usually wired in paralel blocks of several serial connected diodes. This means that current consumed by the LED strip flows thru the entire strip power wiring, right? So if I connect for example 2 strips in series, I will double the current flowing thru both strips. Is this right?

If it is, how much current can typical LED strip handle? I could not find this information for every single LED strip I tried, I only assume this is given by the width and thickness of the copper wire of the flexible PCB used.

Best Answer

Let's say that this is a LED strip:

schematic

simulate this circuit – Schematic created using CircuitLab

The voltage at the ends of D1...Dnv line is the same as the voltage across D1a..Dna and D1x...Dnx and is equal to the supply voltage because they are connected in parallel.

The current drawn by the whole strip is the sum of currents drawn by each series strip like D1...Dn. The current drawn by a single LED is equal to the current drawn by the other LEDs in series with it. Only the voltage is lower because they are connected in series.

So, to supply similar devices with the normal voltage/current:

  • parallel: voltage remains the same across every element of the circuit and it is the voltage of the supply. The supply must be able to provide a current which is at least the sum of all currents drawn by each parallel device
  • series: current remains the same for every element of the circuit. If the devices draw different currents then they shouldn't be connected in series. The voltage of the power supply must be equal to the sum of voltages required by each device.

If you connect LED stripes in series, then you'll need the same current as for a single LED strip but a voltage n times greater, where n is the number of stripes you are using.

Only connect in series identical LED strips with the same ratings!

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