When it comes to setting up a dual battery system in your vehicle, a 12v split charge relay is an essential component. It allows you to charge your auxiliary battery while driving, ensuring a consistent power supply for your accessories, without draining your main battery. A split charge relay is relatively easy to install, but it’s necessary to understand the wiring diagram to ensure proper setup.
What is a 12v Split Charge Relay?
A 12v split charge relay is an electronic device that connects to two batteries. It charges the auxiliary battery while the vehicle’s engine is running, and disconnects it when the engine is off. This way, the auxiliary battery receives power while driving, and the main battery is not drained. The split charge relay is commonly used in campervans, boats, and other vehicles that require a dual battery system.
How Does a Split Charge Relay Work?
A split charge relay works by using a small amount of current from the main battery to energize its internal switch. This switch then connects the auxiliary battery to the alternator, allowing it to be charged while the engine is running. When the engine is turned off, the switch disconnects the auxiliary battery, preventing it from draining the main battery.
Why Use a Split Charge Relay?
Without a split charge relay, the auxiliary battery would drain the main battery, leaving you stranded in the middle of nowhere. Additionally, a fully charged auxiliary battery provides backup power for your camping trip or outdoor adventures. A split charge relay ensures that your auxiliary battery is always charged, and your accessories have a consistent power supply.
Wiring Diagram for a 12v Split Charge Relay
The wiring diagram for a 12v split charge relay is relatively simple. You’ll need a few essential components, including the split charge relay itself, a main battery, an auxiliary battery, and some cables.
| Component | Description |
|---|---|
| Split Charge Relay | An electronic device that connects to two batteries. |
| Main Battery | The primary battery that powers the vehicle. |
| Auxiliary Battery | The secondary battery that powers accessories. |
| Cables | Wires that connect the components together. |
Step-by-Step Split Charge Relay Wiring
Follow these steps to wire a 12v split charge relay in your vehicle:
Step 1: Disconnect the Battery
Before connecting any wires, always disconnect the negative terminal of the main battery to prevent electrical shock and damage to the vehicle.
Step 2: Mount the Split Charge Relay
Mount the split charge relay in a secure location close to the main battery. This ensures that the cable runs aren’t too long, which can cause voltage drop and affect the charging system’s performance.
Step 3: Connect the Main Battery to the Split Charge Relay
Connect a cable from the positive terminal of the main battery to the input terminal of the split charge relay.
Step 4: Connect the Auxiliary Battery to the Split Charge Relay
Connect a cable from the positive terminal of the auxiliary battery to the output terminal of the split charge relay.
Step 5: Connect the Split Charge Relay to the Alternator
Connect a cable from the split charge relay’s sensing terminal to the alternator’s positive terminal. This completes the circuit, allowing the split charge relay to energize and connect the auxiliary battery to the alternator.
Step 6: Connect the Negative Cables
Connect a cable from the negative terminal of the main battery to the vehicle’s chassis, and another cable from the negative terminal of the auxiliary battery to the same point. This ensures that both batteries have a common ground.
FAQ
What Size Cable Should I Use to Connect the Batteries?
The size of the cable depends on the amperage rating of the alternator and the distance between the batteries. A general rule of thumb is to use a cable that can handle twice the amperage of the alternator and a distance of less than 1.5 meters between the batteries. Consult an electrician for more specific sizing requirements.
What Happens if the Split Charge Relay Fails?
If the split charge relay fails, the auxiliary battery will no longer be charged while driving, and the main battery might drain if too many accessories are used. In this case, it’s best to replace the split charge relay as soon as possible to avoid further damage to the charging system.
Can I Use a Split Charge Relay to Charge More than Two Batteries?
No, split charge relays are designed to connect only two batteries. If you require more than two batteries in your system, consider using a battery isolator or a DC-DC charger instead.
Conclusion
A 12v split charge relay is an essential component of a dual battery system. With proper installation and wiring, it ensures that your auxiliary battery is always charged, and your accessories have a consistent power supply. Follow the wiring diagram and steps mentioned in this article to install a split charge relay in your vehicle, and enjoy your outdoor adventures without worrying about power supply issues.
