How Much Power do LED Strips Really Require? (Perhaps Less Than You Expect)
In order to buy the right power supply for your LED strip project, you need to determine the power requirements of your LED strips. It may seem simple to calculate this by visiting the LED strip’s product page and checking the energy usage, usually listed as W/m (Watts per meter). However, it’s not as straightforward as it appears.
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Color Strips Are Often Less Power-Hungry Than You Think
For single-channel LED strips, the calculated maximum power should be relatively accurate. However, for multi-channel LED strips, where you have a controller to adjust the power for each channel and create the desired color, the actual power consumption is typically much lower than the stated maximum.
Let me give you an example. I recently installed RGBCCT LED strips with five channels above the crown molding in my dining room. The product listing showed a maximum power usage of 12W/meter. The perimeter of my dining room is about 42 feet, approximately 14 meters. Therefore, I initially expected a maximum power usage of:
12W/m * 14m = 168W
However, after installation, I used my trusty Kill A Watt to measure the power consumption and found that the lights were only drawing a maximum of 50W. That’s significantly less than the expected 168W!
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Not All Channels Are Used Simultaneously
The reason for this difference lies in the LED controller. In my case, I used a Gledopto Pro Zigbee controller connected to the Philips Hue app. When using the color spectrum, only the RGB channels are used, while the WW and CW channels remain unlit. Conversely, when using the white spectrum, only the WW and CW channels are used, with the RGB channels unlit.
This means that at any given time, a maximum of three channels will be used. So, if only three out of the five channels run at maximum power, the new maximum usage should be:
(3/5) * 168W ≈ 100W
Already, this is a significant reduction. But there’s more to it!
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Consistent Brightness Between Colors
To ensure consistent brightness as you change colors, the controller makes additional adjustments. For instance, when transitioning from pure red to a color in the center of the color wheel, you are going from one channel at 100% power to three channels at 100% power. Without adjustment, this would result in a noticeable difference in brightness. To compensate, the controller lowers the power of each channel as more channels are mixed in.
This approach creates a relatively even brightness, regardless of the color you choose. It also leads to a substantial drop in maximum power usage.
To illustrate further, let’s look at the real numbers from my dining room setup. When I set the color to pure red, only the red channel runs at 100% power, while the other channels are off. In this case, the Kill A Watt reads 39.0W.
Next, I set the color to the center of the color wheel, which requires an equal mix of the three RGB channels. One might expect the controller to run all three RGB channels at 100% power, but that’s not the case. Instead, the power usage is 41.4W.
>>>> more: How Much Power do LED Strips Really Require?
What If You Want to Use LED Strips at Full Power?
Of course, the downside to controllers automatically adjusting power is that you can’t make full use of the LED strip’s maximum brightness. If you prefer full control, there might be controllers available that allow you to manually control each channel. Unfortunately, I’m not aware of any. If you know of a way to do this, please share!
What I do know is that for my demonstration, I used a Gledopto Pro 1ID controller, which treats the LED strip as a single device. This simplifies usage but prevents the RGB and CCT LEDs from being used simultaneously. Gledopto also sells a 2ID model that treats the RGB and CCT LEDs as separate devices, allowing simultaneous usage but still automatically adjusting brightness.
Different controllers may behave slightly differently, but the ones I’ve seen all work similarly.
Final Thoughts
The key takeaway here is that if you’re using an RGBCCT LED strip with a commonly available controller, the actual maximum power usage will be significantly less than the LED strip’s maximum (about 1/3 in my case). This means you can use a smaller power supply than originally planned, reducing the cost and complexity of your project.
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