How to Charge an RV Battery from a Vehicle

Charge your RV battery from your vehicle efficiently and safely with the right equipment and setup. This guide will help you understand the different methods and considerations involved in charging an RV battery from a car or van.

Understanding the Charging Process

When it comes to charging an RV battery, you have several options, including using a built-in charger in your vehicle or employing a generic charger. However, the most suitable approach depends on the battery's specifications and the charging equipment you have available.

Charging with a Personal Charger

Any charger can be used to charge an RV battery, provided the charging rate matches the battery's requirements. Typically, the charging rate is 1/10 of the Ampere-hour (Ah) capacity of the battery. For instance, if your RV battery is 12V and 100Ah, a charger with 10 Amps of capacity will suffice.

Ensure that the charger's current capacity does not exceed the ampere-hour rating specified on the battery. Using a charger with a higher current capacity than the battery's ampere-hour rating can result in overcharging and potential damage to the battery.

Voltage Considerations

While the voltage of the charger and the battery should match (typically 12V for both), you should be aware of the differences in charging times. High-amperage RV batteries will take longer to charge using a standard car charger due to their larger capacity.

Using a DC to DC Charger

A DC to DC charger is the recommended method for charging an RV battery. It allows you to match the charging speed to the battery's size and charging requirements. A DC to DC charger provides a controlled charging process, ensuring that your battery is charged without exceeding its capacity.

Consider the size of your battery bank and the speed at which you want to charge it. Factors such as the charger's output voltage, current, and efficiency should all be taken into account. Additionally, you can also set up a dual alternator system, one configured for the battery you want to charge, to provide a steady and reliable charging source.

Connecting to a Ford Truck Charging System

Many Ford trucks come equipped with a diode and a connection point for auxiliary battery charging via the vehicle's electrical system. This setup is conveniently located in the electrical distribution box on the driver's side engine compartment.

For optimal charging, you need to run appropriate gauge wire to the battery bank. The wire size should adhere to safety standards, considering the AWG (American Wire Gauge) rating. For instance, 15 amps of current would require a 14 AWG wire, as 15 x 0.80 12, and this is the minimum safe current. For higher currents, a larger wire or parallel wire runs may be necessary.

Connecting Batteries for Charging

To charge an RV battery using another battery, follow these steps:

Ensure you use appropriate gauge wire to prevent short circuits. Connect the positive lead of the auxiliary battery to the positive lead of the RV battery. Connect the negative lead of the auxiliary battery to the negative terminal of the RV battery.

Note that the charging rate of the fused system may be 1.5 volts lower, making it unsuitable for charging a dead battery. This setup is primarily for maintaining a charge in the auxiliary battery.

Conclusion

Charging an RV battery from a vehicle requires a well-thought-out and properly equipped system. Whether you opt for a DC to DC charger, a dual alternator setup, or a built-in vehicle charging system, make sure to choose the right method for your specific needs to ensure your RV battery remains in top condition.