What size relay for light bar?

Are you looking for the answer to what size relay for light bar, we are going to explain this in the article? We will deal with the explanation of how this works and some easy strategies for different cars. So, you don’t have to feel frustrated when you buy one for your car and it does not work.

what is a relay for on a light bar?

A relay is a device that connects between a control circuit and a device that you want to control. The relay has three terminals: One is connected to the control circuit. Another is connected to the device. Another is connected to whatever is providing the current. When someone wants to control the device, an electric current passes through the control circuit and through the relay. This sends power to the device.

The device will stay on as long as the control circuit is sending a current through the relay. When the control circuit stops sending the current, the device will turn off. One example of the relay is in a light bar. Most car light bars have a button on them with a word “ON” and “OFF”. The button actually activates a relay that turns the lights on and off.

What size relay for light bar?

The size of the relay depends upon the power consumption of your light bar and the size of the battery. If the battery can support the load, then a 15 amp relay is a good size. If the battery and load are higher than 15 amps, then a 20 amp relay will be necessary. The relay should be an SPST or SPDT depending on the wiring pattern of the vehicle. If it is a truck, then you can use the SPST. There is no benefit of SPDT over SPST.

Do I need a relay for a light bar?

Yes, a relay is required for a light bar. The Voltage and the Amperage need to match up. When it comes to installing a light bar on your vehicle, you have to make sure that the voltage of the vehicle is consistent with that of the relay. All relays are made for 12-volt systems so if your car has a different voltage powering it then there’s a possibility that it may not work effectively. If you have a 24-volt system, then you will need to find a relay that is capable of handling 24 volt systems.

Yes, a relay is required for the light bar application for three reasons:
  1. Save your vehicle battery to run electronics at the same time.
  2. Prevent too much voltage drop when using multiple lights.
  3. Reliable on/off control. The following is a basic circuit diagram for a simple light bar application.

What kind of relay do I need for LED light bar?

There are some factors you should consider while selecting relay. The first one is the voltage load. The relay you need needs to be able to handle that amount of load. The second factor is whether or not you will be controlling the relay with a PWM controller or not. If you need to control it with a PWM controller, then you will have to select a relay with an internal PWM controller.

What amp draw requires a relay?

Relay is an electromechanical device that switches current/voltage in accordance with the input signal. Relays are mainly used for switching high current/voltage and more importantly, the path between the input and output is not directly connected. A relay can only be used when the voltage/current draw is more than 10% of the relay rating. However, the actual percentage depends upon the design and brand of the relay. But the general rule is, if the relay is rated for 5A, it can be used for switches up to 6A.

Where to mount relay for the light bar?

led light relay wiring diagram

A lot depends on your mounting method for the light bar. If you plan to make your own mount, then you can drill a hole in the fender or somewhere else convenient for your bike.

For those who are purchasing amounts from a third party, it is important to check the specific instructions for the mount. The light bar should have a similar hole for an electrical connection, which the relay will connect to. Optionally, you can drill a hole in your handlebars to run the wires through. The best location is to mount the relay somewhere closer to the battery than the headlight.

LED light bar relay problems

One of the common problems related to the LED light bar relay is the wiring. The relay needs to be connected in a proper manner. It should not be connected in reverse order. The soldering too should be perfect. If the wiring is faulty, the damaged cable can be replaced with a new one. You can use a multi-meter to check the voltage of the circuit.

The reading should be consistent. You can also use a relay tester to check whether the relay is working correctly or not. The tester is available at many auto parts stores. It can be used to test relays for voltage, current, resistance, and continuity.

The most common reasons why LED light bars relay problems are as follows:

  • Improper circuit connection
  • Poor contact between terminal and copper wire
  • Poor contact between the copper wire and the terminal
  • Popper wire is too thin and is easy to tear
  • The terminal is inserted at an angle
  • Use of wrong terminal size.


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