Using a 12V LED Strip in a 24V System

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Using a 12V LED Strip in a 24V System

You may be familiar with the differences between 12V and 24V DC systems and the various advantages they offer. But you might still be stuck with a mismatch between an LED strip at 12V and a power supply at 24V.

While we strongly recommend using products and accessories that have matching specifications, we'll show you how one can connect the 12V LED strips to the 24V power supply without (in theory) damaging the LED strips!

Before we show you how to connect the 12V LED strip to a 24V power supply, please read:

Disclaimer: Incorrect or accidental connections that lead to over-voltage can cause permanent damage to the LEDs. The information provided here is for educational purposes only. Waveform Lighting does not take any responsibility for any damage.  To be safe, we recommend testing with a small LED strip segment to ensure that the setup works prior to connecting a longer section.

Series vs Parallel

Let's first take a look at the circuitry of a 12V LED strip. It's tempting to think of an LED strip as being many LEDs in series because of the way they are laid out linearly, but in reality, a 12V LED strip is usually many parallel groups of 3 LEDs. The 12V is comprised of 3 LEDs in series at 3 volts each, and a current limiting resistor that also corresponds to 3 volts or so, for a total of 12V.

Each subsequent group of 3 LEDs, even though they are linearly laid out, are actually connected to each other in parallel. The copper pads on the LED strips are therefore all equivalent in terms of voltage.

For a 12V LED strip, the voltage difference simply just needs to be 12V for it to operate as intended.

Connecting 24V to 12V LED Strips

Simply connecting 24V to the 12V LED strip copper pads will obviously cause the LEDs to burn out due to over-voltage. So, what can we do that doesn't involve any transformers or additional accessories?

The most straightforward way to force a 12V LED strip to work in a 24V system is to split a 12V LED strip into two identical 12V LED strip segments and connect the copper pads in series, such that the sum of the voltages adds up to the 24V supplied by the power source.

By connecting the LED strips in this way, the 24V power source is effectively "split" between the two LED strip segments which expect 12V each. Because the two LED strips are connected in series, the current draw for each LED strip will be identical.

Warning: the two LED strips connected in series must be IDENTICAL!

In the example above, we mention the fact that two LED strips are forced to draw the same amount of current due to the fact that they are connected in series. This is expected and not an issue since the LED strips draw the exact same amount of power due to their identical length and power draw specification.

But the two LED strips must be identical!

Why is this so important?

Let's imagine two 12V LED strips with different lengths connected in series, such that at 12V they draw 0.5A and 1.0A, respectively.

Since they will be connected in series, they will be forced to share the same forward current value. Let's suppose that current value happens to be 0.75A - the midpoint.

For the longer LED strip, to match the lower current of 0.75A vs the rated 1.0A, the voltage may need to drop to 11V or even 10V. But the 24V constant voltage input is, by definition, constant at 24V. So the shorter LED strip segment is now forced to "make up" the remaining 13 or 14V. This will lead to an overcurrent situation in the shorter LED strip, potentially causing damage to the LEDs.

Going the other way - 24V LED strips on a 12V power supply

If you're trying to go the other way and connect a 12V power supply to operate 24V LED strips, unfortunately, you are out of luck. You'll need to purchase a transformer or voltage booster, or, more straightforwardly, a 24V power supply.

The reason is that a 24V LED strip has 6 LEDs in series per group, and there is no way to "split" this to match a 12V power source. Simply put, the copper pads need a 24V voltage differential for the LEDs to operate.

Bottom Line

In theory, connecting two identical 12V LED strip segments in series can be a solution for pairing with a 24V power supply. In practice, however, it can be somewhat risky and we recommend going down this path only if you're in a pinch!

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