Relay 12V
- Updated:
- By: Kevin van Mierlo
Contents
What is a 12V relay?
A 12V relay is an electrically operated switch that uses a low-voltage signal to switch a high-voltage circuit on or off. It is often used in cars, trucks and ships to efficiently control accessories such as horns and headlights without direct mechanical action.
Electromechanical relays that work by activating an electromagnet to attract a set of contacts to make or break a circuit. They are mainly used to activate horns, headlights and fan motors. A 4-pin 12V relay connects to both the positive and negative sides of the vehicle power source via a switch, providing efficient current regulation.
How a 12V relay works
Relays are installed between the power source and the electrical accessory that needs on/off power. When the relay is energised, the high current to operate the accessory flows from the power source through the relay and directly to the component.
When to use a 12V relay
Relays are crucial when it comes to controlling a circuit with a low-power signal, where complete electrical isolation between the controlling and the controlled circuit must be ensured. In addition, relays are used to manage multiple circuits with just a single signal.
Connecting 4-pole 12V relays
A 4-pole relay offers a lot of flexibility and control options compared to other types of relays. These relays have four connections that can be configured in different combinations of open and closed states, such as two open and two closed, three open and one closed, or all four open.
| Pole number | Connection | Description |
|---|---|---|
| 86 | Control current input | The PIN where the control voltage enters the relay, used to activate the coil. |
| 85 | Output control current | The return pin for the coil, usually connected to earth. |
| 30 | Main power input | The common power input for the relay, the source of the main current. |
| 87 | Output main current | The output where the main current leaves the relay when activated, to the switched device. |
This versatility makes it possible to control complex circuits and adapt them to specific system needs, such as simultaneously managing multiple circuits with different current requirements. 4-pole 12V relays use 2 pins (85 & 86) to control the coil and 2 pins (30 & 87) that switch the current on one circuit.
There are 2 types of 4-pin relay available; normally open or normally closed. A normally open relay switches the voltage ON for a circuit when the coil is activated. A normally closed relay switches the voltage OFF for a circuit when the coil is activated.
Connecting a 3-pole 12V relay
A 3-pole relay has three connections and is more limited in configuration, often only having the ability to operate in a normally open state. This means that current only flows through the relay when it is activated. Such relays are simpler and are often used for basic on/off switching tasks where no complex circuitry or multiple output configurations are required.
How do you connect a 4-pole relay?
To connect a 4-pole relay, connect PIN 85 to earth and PIN 86 to the control voltage to activate the coil. PIN 30 is connected to the power input and PIN 87 to the device you want to switch. This switches the current when the relay is activated.
Canbus proof i-LS Relay
For the automotive industry, we recommend the i-LS Relay from LED Autolamps. The built-in microprocessor prevents unreliable interference signals being generated by indicator lights. Which can be caused by the extremely low current draw of LED lights when installed on traditional incandescent lighting systems.
The i-LS relay is designed for use in conjunction with our i-LS microprocessor. This enables you to reliably detect interference in an LED indicator.
The system warns the driver when an indicator is faulty by speeding up the indicator.
Video: 12V Planet
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Kevin van Mierlo
Lighting expert at TRALERT® - Kevin tests lighting and finds out everything about legislation. He can tell you all about it.
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