Can You Operate a 12V LED Strip at Less Than 12V?
But what does "required" mean? Quite intuitively, providing more than 12V DC on a 12V LED strip is not a good idea, because you may cause the LED strip to be over-driven, burning out the diodes or causing excessive heat buildup that can damage both the circuit and on-board components. But what if we supply 11V, or even 9V? Is that "allowed"? Is it bad for the LED?
The short answer is no, not at all - using a voltage level lower than the specification is perfectly acceptable and safe. We also ran some tests to provide you with some real-life data so that you know what to expect if you choose to under-drive your LED strip lights.
Why Does This Matter?
Before we get into our test setup and results, you might be wondering in what situations an LED strip might be under-driven, or if under-driving an LED applies to your particular set-up.
LED strips are designed at the circuit level to be paired with a specific voltage in mind. For example, we offer 12V and 24V DC power supplies to go with our 12V and 24V DC LED strips, and in most cases, the voltage will be an exact match.
Virtually all specifications, such as power draw per foot and lumens per foot assume that the supplied voltage is exactly at the rated voltage level (i.e. 12V DC or 24V DC).
That being said, it is perfectly safe and permissible to under-drive an LED strip by supplying a lower voltage than the rated voltage. But most LED strip products do not publish any information on how and to what extent under-voltage affects LED strip performance, and that is why we decided to conduct our tests. Our test results show some rough estimations that can be used.
There are three primary situations in which you may have a power supply voltage that is lower than the LED strip voltage specification. The first is an intentional choice to use a lower voltage to achieve a lower light output than the rated light output. You might, for example, find that 450 lumens at 5.5 watts per foot is too much for your needs, and you instead would prefer to run the LED strips at 2.3 watts per foot. Using a 20V power supply on a 24V LED strip could be a simple and effective way to achieve this without needing to purchase and install a dimmer.
The second situation may arise out of existing system constraints. If you intend to install your LED strips on a battery system, for example, the power supply voltage may drop below 12V DC as the system discharges. Our data below should prove useful in determining what level of power consumption you can expect if and when the supply voltage drops below the LED strip's rated voltage.
The third situation can be caused by insufficient wire gauge and resulting voltage drop. When too much current passes through a long copper wire that does not have enough thickness, the voltage level can drop before it even begins supplying power to the LED strip.
Our Test Setup
We took a 1-ft (30 cm) segment of our Ultra High 95 CRI LED strip lights, and hooked it up to a benchtop power supply. The benchtop power supply has variable input voltage capability, and we measured the current draw as a function of input voltage, in 0.1V increments.
We repeated this test for both the 12V and 24V versions.
We first measured the current draw at their respective rated voltage, and then decreased the voltage in 0.1V increments, and took the current draw reading. Below are the results plotted on a chart.
Important: note that these results are based on limited tests of our own LED strip lights only. Results will differ among different products and manufacturers.
Our Test Results
Below are a graph showing the relationship between input voltage and power draw (calculated by the input voltage x current draw). You will see a fairly linear relationship between 1.0 watts per ft and 5.0 watts per foot.
General Takeaways from Our Test Results
What we first notice is that the LED strips do not light up until a minimum threshold voltage. This is approximately 7.5V for 12V LED strips, and 15.5V for 24V LED strips. This is a bit counter-intuitive, since this implies that you cannot simply expect a 6V power supply input on a 12V LED strip to simply produce half the power. (Learn more about how diode voltages and circuits work, and why this is the case).
After this minimum threshold voltage, power draw increases by approximately 1.0 watts per foot every 0.75 volt and 1.5 volt increase for 12V and 24V LED strips, respectively.
A common voltage level for laptop power supplies is 19.5V DC, so you might find these results useful if you're in a pinch, and that is the only power supply you have on hand. According to our results, a 19.5V DC input will provide a power level of approximately 2.0 watts per foot on a 24V DC LED strip, a quick and easy way to intentionally reduce light output by about 60%.
Downsides to Under Voltage Operation
As we mention above, under-driving LED strips by using a lower voltage than its rated voltage is completely safe and has no detrimental effects on the LEDs or the circuitry.
If anything, by driving them below their rated current, the LED strips' theoretical lifetime and longevity will be even longer.
From a technical standpoint, there really aren't any downsides. From a practical perspective? The only downside would be the fact that you are in a way over-paying for power capacity.
A good quality LED strip is designed to comfortably provide a certain level of brightness, and it therefore is designed with the appropriate number of LEDs per foot, as well as sufficient copper thickness to handle the power. This inevitably means you are paying more for higher quality and quantity of components & materials, but by under-driving them, you are not utilizing them to their fullest extent. You could say it's a bit like buying a sports car, but not driving it any faster than 50 miles per hour.
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