5 Ways for Charging an RV Battery: Best Practices

Whether you're using shore power or off-grid, knowing the right RV battery charging methods ensures your systems run smoothly. In this guide, you'll discover the most efficient and safe ways to charge your RV battery.

5 Methods to Charging Your RV Battery

There are five reliable ways to charge your RV battery:

Shore power
Generators
Solar power
Vehicle alternator
Battery Charger

Method 1: Using Shore Power

Shore power is a common method of charging an RV battery when you have a power connection at a campground or RV park. When you plug your RV into an AC outlet, the built-in converter transforms the AC power into DC to charge the battery.

To recharge your RV battery using shore power, connect your RV battery’s converter to a 120V AC outlet at a campground or other power source. Make sure the converter is functioning properly, then allow the built-in converter to transform the AC power into DC. Use a battery monitor to check the battery's charge status to avoid overcharging, and unplug once it’s fully charged.

charging an RV battery with shore power

Method 2: Using a Generator

Using a generator is a reliable way to charge your RV battery, especially when you’re off the grid and lack access to electrical outlets. Many RVs come with a generator for emergency use.

Most generators output AC power, and your RV’s converter will handle the charging process. To charge your RV battery with a generator, connect the RV’s converter to the generator’s 110-120V outlet. Ensure the generator is positioned in a well-ventilated area and has enough fuel. Once connected, the generator will supply AC power, which the RV’s converter will convert to DC for charging. Keep an eye on the fuel level and battery charge to avoid any interruptions.

Method 3: Charging with Solar Power

Solar power is perfect for longer off-grid stays, and offers a quiet, fuel-free option. With solar panels installed on your RV or portable panels set up outside, the system captures energy from the sun and directs it to your batteries through a solar charge controller. The controller ensures a safe, steady charge.

With up to 99% peak conversion efficiency, the Redodo MPPT solar charge controller can track the maximum power point of the array and get the maximum power to charge the battery.

To recharge with solar power, connect one side of the solar charge controller to the solar panel, and connect the other side to the RV battery by attaching the positive (red) and negative (black) leads to the corresponding battery terminals. Position the solar panels in direct sunlight and ensure the controller is set correctly. The charge controller will manage the flow of power, providing a steady charge to the battery throughout the day.

Method 4: Charging with a Vehicle Alternator

For motorhomes and towable RVs, you can charge your batteries while driving. The vehicle’s alternator sends a charge to the RV battery as you drive, helping keep your battery from depleting. For towable RVs, the 7-prong trailer connector carries power from the tow vehicle’s alternator to the trailer battery.

Within the trailer cord plug and outlet, there is a specific connection dedicated to transmitting "auxiliary power." When properly wired, this connection allows for a 12-volt power feed from the tow vehicle's alternator. When the alternator has fully charged the starting batteries, the excess capacity will be sent to your RV battery. This method helps maintain the battery’s charge while traveling between destinations.

Method 5: Charging with a Battery Charger

A dedicated battery charger is a simple grid-electricity solution, especially when shore power or a generator isn’t available.

To recharge your RV battery by using a dedicated battery charger, attach the charger’s positive (red) and negative (black) clamps to the corresponding battery terminals. Plug the charger into an AC outlet and set it to the appropriate voltage and battery type.

Ensure the charger is compatible with your battery type (lead-acid, AGM, or lithium) for optimal performance. Monitor the charger’s display to track the battery’s progress, and disconnect once the battery is fully charged.

If your RV battery is LiFePO4 model, consider the Redodo 12V 20A LiFePO4 battery charger to make charging easier. It charges 2x faster than an ordinary 10A battery charger and can fully charge a 12V 100Ah LiFePO4 battery in 5 hours. It is recommended to charge your RV battery at a 0.2C charging rate.

What is the Fastest Way to Charge RV Batteries?

The fastest way to charge your RV batteries is through shore power or grid power because they provide a consistent flow. The RV’s charging converter efficiently transforms into DC power for fast battery charging.

For example, a 50-amp converter can charge a 12V 100Ah lithium ion battery in about 2 hours on shore power, and a 2000-watt generator offers similar speed with the same converter.

How to Charge RV Batteries in Parallel?

Connecting RV batteries in parallel is a method used to increase the overall capacity (amp hours) while keeping the voltage the same. You need to connect the positive terminal of one battery to the positive terminal of the other battery, and do the same for the negative terminals till the last battery.

Before charging RV batteries in parallel, make sure all of the batteries are of the same brand, type, BMS, and capacity, and the batteries are purchased in near time (within one month). Ensure the charger is compatible with your battery type (lead-acid, AGM, or LiFePO4) and set to the appropriate voltage, typically 12-14.6V.

To charge the RV batteries in parallel, attach the charger’s positive lead to the positive terminal of one battery, and the negative lead to the negative terminal of the other battery. Use two bus bars instead of battery terminals to connect all the positive and negative input cables, ensuring that the currents of each battery are balanced.

6 Tips for Charging an RV Battery

Use the Correct Charger for Your Battery Type

Ensure the charger matches your battery type, whether it’s lead-acid, AGM, or lithium. Using the correct charger prevents batteries from damage.

Monitor the Charging Voltage

Regularly check the voltage during charging to ensure it stays within the recommended range. For a 12V LiFePO4 battery, a safe charging voltage is typically between 14.2V to 14.6V. When the battery is fully charged, unplug it in time to avoid overcharging, which can damage the battery.

Avoid Extreme Temperatures

Charge your RV battery in moderate temperatures. For RV lithium batteries, the charging temperature range is 0°C to 50°C (32°F to 122°F). Avoid charging below 32°F (0°C) or above 122°F (50°C), as extreme cold or heat can harm battery performance and lifespan.

Avoid Deep Discharges (For Deep Cycle Batteries)

For deep cycle RV battery, it's best to recharge it before they reach 20% of their charge. Although deep cycle batteries are designed to handle deeper discharges, regularly depleting them too much can still shorten their life and reduce capacity.

Check for Loose Connections

Before charging, inspect the battery terminals for any loose connections. Secure connections help ensure efficient and safe charging.

Use a Charger with Trickle Charging Function (For lead-acid and AGM batteries)

When the battery is in a charged state for an extended period without requiring a large current, a charger with trickle charging function can provide a small current to keep the battery charged and prevent self-discharge.

Charge and Optimize Your RV Battery Now!

By mastering different charging methods above and following essential maintenance tips, you can keep your battery in top condition for every trip. Consider upgrading to high-quality RV batteries from Redodo, designed for durability and efficiency, ensuring you stay powered no matter where the road leads. Explore today for a worry-free RV experience!

FAQs about RV Batteries

Should I leave my RV plugged in all winter?

If your RV is equipped with a smart charger or battery maintainer, keeping it plugged in is beneficial and help maintain the charge without overcharging. However, if your RV has a simple converter without smart charging, leaving it plugged in continuously can overcharge and damage the battery.

What drains an RV battery when not in use?

Even when not in use, RV batteries can be drained by small appliances. These are called "parasitic loads." Over time, these small energy demands can significantly deplete the battery. To prevent this, disconnect the battery or use a battery disconnect switch to cut off any unnecessary power draws during storage.

How do I know if my RV needs a new battery?

You may need a new RV battery if it is no longer holding a charge or if it consistently dies quickly even after being fully charged. Other signs include difficulty starting electrical systems, visible damage like cracks or leaks, or corrosion that can’t be cleaned off the terminals. If the battery is over a certain number of years, it may be reaching the end of its lifespan and should be tested for performance or replaced.

Comparison of Group 24 VS Group 31 Deep Cycle Batteries

Deep Cycle LiFePO4 vs. Lead Acid Battery