Full Size Cars offer unparalleled comfort and space, but they often come with increased electrical demands. From advanced infotainment systems to power-hungry accessories, the stock battery can sometimes struggle to keep up. For full size car owners looking to enhance their vehicle’s electrical reliability and capacity, especially for aftermarket additions or camping setups, installing an auxiliary battery is a smart and effective upgrade. This guide provides a comprehensive, step-by-step walkthrough on how to install a secondary, or auxiliary, battery in your full size car, ensuring you have ample and consistent power for all your electrical needs.
Preparing Your Full Size Car for a Dual Battery Setup
Before you begin the installation, it’s crucial to ensure your full size car is ready for a dual battery system. The first step is to disconnect the car’s main battery. This is a fundamental safety precaution when working with any automotive electrical system. Always disconnect the negative terminal first, followed by the positive. This prevents accidental shorts while you’re working around the battery terminals.
Alt: Disconnecting negative terminal of car battery, a crucial safety step before installing auxiliary battery system in a full size car.
Next, you need to identify a suitable and safe location to mount your auxiliary battery. In full size cars, common locations include the trunk or cargo area, or even under the hood if space permits. Consider factors like ventilation, accessibility, and protection from the elements when choosing a location. For optimal safety and longevity, it’s highly recommended to use a dedicated battery box to secure the auxiliary battery and protect it from vibrations and potential damage, especially in the often spacious cargo areas of full size cars.
Setting Up the Voltage Sensitive Relay for Your Auxiliary Battery
The Voltage Sensitive Relay (VSR) is the heart of your dual battery system. It intelligently manages the charging of your auxiliary battery by automatically connecting it to the main battery when the engine is running and disconnecting it when the engine is off. This ensures your main battery always has sufficient charge to start your full size car.
Mount the VSR as close as practically possible to your primary starter battery. This minimizes voltage drop and simplifies wiring. Using heavy gauge wire, ideally 6 AWG (American Wire Gauge) or thicker, connect the positive terminal of your starter battery to one side of the VSR. This heavy gauge wire is essential to handle the high current flow necessary for charging, particularly in full size cars which may have larger alternators.
Alt: Wiring diagram illustrating connection of Voltage Sensitive Relay between main and auxiliary car batteries in a full size vehicle, highlighting heavy gauge wiring.
From the other side of the VSR, run another length of the same heavy gauge wire to the positive terminal of your auxiliary battery. Securely attach battery terminals to ensure a solid and reliable connection. A robust connection is vital for efficient charging and power delivery in your full size car’s electrical system.
Grounding Your Auxiliary Battery System
Proper grounding is just as critical as positive connections in any automotive electrical system, and it’s especially important in full size cars with their larger chassis. The VSR will have a negative wire that needs to be connected to the car’s chassis ground. Ensure this connection is made to a clean, bare metal surface for optimal conductivity.
At the auxiliary battery itself, run another heavy gauge wire (6 AWG) from the negative terminal to a solid point on the car’s metal body. Again, make sure this grounding point is on bare metal, free from paint or rust, to guarantee a good electrical connection. Use appropriate connectors on both ends of all wires and thoroughly test the grounding with a multimeter to confirm correct and low-resistance grounding. Effective grounding is crucial for the safe and efficient operation of your auxiliary battery system in your full size car.
Alt: Close-up of a secure grounding point on a car chassis, essential for proper installation of an auxiliary battery in a full size car.
Finalizing and Protecting Your Auxiliary Battery Setup
Once all wiring is complete, double-check all connections for tightness and security. As mentioned earlier, ensure your auxiliary battery is securely mounted. In a full size car, the battery could be subjected to significant movement, so a battery box and secure mounting are paramount.
For added safety and convenience, consider installing a battery isolator inline between your auxiliary battery and your accessories or a distribution fuse box. A battery isolator allows you to quickly and easily disconnect the auxiliary battery from the rest of the system, which is useful for maintenance, troubleshooting, or preventing parasitic drain when the car is not in use for extended periods. This is a valuable addition to any full size car auxiliary battery setup, providing an extra layer of control and protection.
By following these steps, you can successfully install an auxiliary battery system in your full size car, providing a significant boost to your electrical capacity and ensuring reliable power for all your adventures and electrical demands.
