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How to Charge RV Batteries With a Generator? – 2 Methods

Written by Philip Lopez / Fact checked by Paul Lemaire

how to charge rv batteries with a generator

RV batteries usually refer to 12-volt house batteries that need more significant amounts of energy to work correctly. If you want these batteries to work more efficiently, charge them when they’re less than 50% correctly. Lucky for you, I get them all covered with 2 methods below.

The process of how to charge RV batteries with a generator is actually easy. You can use a battery charger or simply connect the RV batteries straight to your generator.

Table of Contents

What You’ll Need


Here are the materials that you need to prepare when charging RV batteries with a generator.

  • Generator

The generator is a handy machine to charge the RV batteries to full power. Typically, a generator needs around 8-amp power and 3,500 capacity to completely charge a 12-volt house battery. However, you can look for a 4,000-watt capacity generator if you want a faster charging time.

Oftentimes, an RV generator uses a converter to offer 12-volt power for your motorhome while hooked to an A/C outlet. Recharging the batteries with a generator usually takes time, so make sure that you turn off all other appliances while doing so.

  • Gasoline

To power your generator on, you’ll need to fill the tank with gasoline or other fuel. Typically, a 5,000-watt generator consumes one gallon of gas per hour. A 5,000-watt generator run by propane consumes about 1-1.5 gallons of propane each hour.

Check the fuel tank capacity to know how much fuel your generator can hold. If you want the generator to work longer, look for a generator with a large capacity tank.

  • Three-Stage Battery Charger (only for Method 2)

A three-stage battery charger is a good replacement for a normal RV converter. This type of charger is fully automatic and will recharge the RV battery faster. More importantly, it can minimize the power to prevent battery overcharge.

When buying a charger, look for one that suits your RV battery type. The most basic type of RV battery is flooded lead acid or wet cell, which suits most types of chargers.

Now, determine the battery size in amp-hours. A typical auto battery is around 50 amp hours, so look for a 10-amp charger that would recharge for six hours.

  • Gloves

When dealing with a portable generator, you need to wear gloves for hand protection. You can avoid many small incidents when you take correct precautions when operating this type of heavy equipment. Choose rubber insulating gloves to protect yourself from electrical shock.

The best gloves for operating with generators should be comfortable and adequately durable to last for many uses. Don’t forget the leather protectors to give maximum electrical safety. Make sure that the leather protectors should be as big as the rubber insulating glove.

  • Safety Goggles

To protect yourself from sudden electrical discharge, consider wearing safety glasses. More specifically, a pair of dielectric safety glasses fit in operating with a portable generator. This type of goggles is designed with a non-conducting frame without any metal parts.

Check the lens coatings and make sure that they can make the eyewear last longer. The most durable lenses are scratch-resistant. Look for an anti-fog model if high humidity and diverse temperatures are a concern.


  • Adapter

If the shore plug on your rig is 30A, then you might need to use an adapter. You can skip with this device if you have the standard 15A plug. Some generators may already have the 30A plug, so it relies on what model you purchased.

When buying a new adapter, make sure that the voltage and current ratings are compatible with your generator. The voltage should be the same and the amperage equal to or greater than the generator you have. Aso, the adapter’s polarity has to be the same.

  • Baking Soda + Water

Before charging, you need to clean the RV battery’s terminals from any dirt and debris. A combination of water and baking soda will do the trick. Baking soda helps loosen and dissolve the dirt in water, making it potent for cleaning.

You need a little water to dissolve the baking soda properly. The mixture should bubble up intensely and foams for a couple of minutes. Typically, the baking soda becomes more effective if it bubbles more.

  • Wire Brush

The wire brush comes in handy when you try to eradicate any leftover rust. Use this cleaning tool after applying the baking soda mixture around the terminals. Since the terminals are more delicate, look for a brass bristle wire brush.

On the other hand, stainless steel bristles clean faster and tougher on corrosion, but you need to be extra careful not to damage the terminals. A little effort is enough to remove the rust when using stainless steel ones.

Step-By-Step Instructions


Now that you’ve gathered all the necessary materials above, here are the steps you should follow. Pick between these two methods to suit your preference.

Method 1: Plugging Directly To The Generator

This method is very straightforward, but it can take much time. When using this method, make sure to turn off all other appliances that are hooked up to the generator. This way, the generator will recharge your RV batteries effectively.

Step 1: Inspect The RV Battery

Before recharging your RV battery, do a little checkup. First, turn off your rig and conduct a visual checkup of your RV battery. Inspect for cracks, swelling, or corrosion because these problems can shorten the battery’s lifespan.

If you see any rust, scrub the terminals with a baking soda mixture and a small wire brush. Don’t forget to take out the cables from the terminals of your battery before doing the cleaning. Also, wear your safety goggles and gloves for protection.

Step 2: Check Your Shore Power Plug

Unhook all other appliances from your generator to optimize charging capacity. Next, check your rig’s shore power plug. If it’s a 30A plug, use the adapter. You’re pretty much set up if the plug is 15A.

Other generators might have these outlets, so it depends on what model you owned.

Step 3: Power On And Charge

Now, fill your generator with gas or other fuel required. Once done, turn on the power and let your generator run for about 3-5 minutes before hooking in the RV.

There’s no exact time how much the charging lasts, but this method tends to take much more time and consumes more gas than Method 2.

Method 2: Using Three-Stage Battery Charger

This particular method charges faster, but it involves a little more work. A three-stage battery charger quickens the charging process, hence consumes less fuel.

Step 1: Disconnect The Battery Form The System

First, disconnect your RV battery from the system. Find the Battery Disconnect Switch in your rig to ensure that we’re not powering other appliances in the generator. If you’re uncertain, read your owner’s manual.

Step 2: Prepare For Charging

This step is the same as Method 1’s Step 1 and 3. Check the RV battery for any corrosion and other indications of damage. Remove any rust with baking soda mixture and wire brush.

After the visual inspection, fill your generator with gas. Let your generator operate for around 3-5 minutes. Again, wear your safety goggles and gloves.

Step 3: Connect The Battery Charger

Now, hook your three-stage battery charger to the generator. Look at the status lights to ensure that the charger is working correctly.

Hook the black negative cable of the battery charger to the battery’s negative terminal. Do the same with the positive cable and terminal. Make sure that the terminal’s metal parts don’t get into contact with any other metal materials.


It’s important that you know how to charge RV batteries with a generator, so you can have a hassle-free road trip. Remember, always wear your safety gear always to protect yourself from accidental electric shocks. Read the product manual before doing any maintenance for safety.

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