How to calculate LED controller output?
LED controllers are a vital part of the lighting control system. LED controllers are employed to regulate the LED strips, change the colour for RGB and RGBW LED strip lights. Controllers also adjust the colour temperature of colour temperature changing CCT LED strip lights and change the brightness of single-colour, white LED strips to different light levels.
You may have seen LED controllers with various outputs in the market and you may be confused about how it works with the power supplies you have. The LED strip controllers are available in the market with output wattage in the range of 60W and 180W across 4 channels. It sometimes confuses users when trying to know if their power supplies have the right wattage for the LED strip to cover. It may appear that the controller is telling it can manage high wattage drivers but it is not the case and we have to consider it in terms of amperage.
Let’s take an example of an LED strip controller which states the power output of 4 x (60-180) W. It doesn’t imply that you can add the maximum driver load of 720W and it will work normally. In contrast, it means that the LED controller can handle a maximum of 5 amperes per channel. Here is the calculation to convert the wattage to amperes. LED strip controllers usually work at the range of the volt between 12 and 36 V, so we can get the amperage by dividing watts by the volts. For instance:
12 Volts = 60 W (60/12 = 5 Amps)
24 Volts = 120 W (120/24 = 5 Amps)
36 Volts = 180 W (180/36 = 5 Amps)
While doing the calculation for LED controllers and LED strips, we should remember some simple and basic rules. In case the LED strip controller can handle a maximum of 5 amps per channel, you have to ensure that the number of strips being installed to a single strip controller is done considering the safety.
It doesn’t mean that you fed the strip controller to its maximum limit as it can damage the controller and LED strips. We should always calculate the output amperes for overhead and it sometimes means settling on 3 or 4 amps. There are always loopholes in the case event and you require a lot of meters covered. One of them is by simply doubling up the LED strip controller and combining them to the same zone. In case the LED strip is a single colour, you can choose a controller and bridge the channels to generate a maximum current of 10 amps per channel.
For instance, consider an LED strip with 14.4 watts per meter that run for up to 20 meters to a single strip controller. In this case, the output wattage will be 14.4 x 20 = 288W. To calculate for overhead, multiply 288W by 1.2 and it will come out to be 345W, so a 350W power supply will be required. Until you make the calculations right for your driver size and consider the 5 amps rule, you will not experience any problem.
When operating a specific length of an LED strip light through either a single colour or multi-colour controller for dimming purposes, it is essential to know that we should not surpass the number of permissible amperes per channel which is usually 5 amperes per output channel for many controllers. It is also important that you don’t run the controller at its maximum allowed capacity to prevent overheating and damage to the LED strip and controller. To safely handle the flowing current to the LED, you should always make use of a suitable wiring diameter.
The right way to calculate the total wattage is to use the equation given below:
Total wattage = length of LED strip x strip watts per meter
For instance, an LED strip having 14.4 watts per meter, the calculation will be:
5 (meter) x 14.4 (watt/meter) = 72W (in case the LED strip is 24V, then 72W % 24V = 3 Amps)
Let’s take another example of an LED Strip having 19.2 Watts per meter current, the calculation will be:
5 m x 19.2 W/m = 96W % 24V = 4 Amps
If the LED strip has 28.8W/m the current calculation will be:
5 m x 28.8 W/m = 144W % 24 = 6 Amps
In the last example, you can see that the current flow across the LED strip controller connection terminal is 6 amps for a particular channel. It implies that we need to check and regulate the way we wire the LED strips to the terminals. A very simple way to do this is by a process we called "Bridging".
As is the case each of the 4 output channels has a current limit of 5 amps but what to do if we need more? If it is the case, we can use 2 output channels from the LED strip controller and join them in parallel to a single cable, so that creating 10 amps effectively, which we will feed to the LED strip.
It is important to remember that you can’t bridge all 4 output channels but it is okay to bridge channels 1 and 2 separately to make it able to handle a maximum current of 10 amps and similarly bridge channels 3 and 4 to make another 10 amps bridged output. So, keep in mind that you can’t bridge all 4 channels together.
If the calculation is made for multicolour LED strips, the calculation will be:
5 (m) x 14.4 (W/m) = 72W
And in case the LED strip is 24V, then 72W % 24V = 3 Amps %4 = 0.72, or 1 amp per channel
You should always ensure that the calculations for amps per channel are made correctly. Feeding too much load on your LED strip controller will lead to severe damages to your strips and LED strip controller and can even cause a fire.