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How to Charge an RV Battery With a Generator Properly?

Writen by Dane Heldt

Fact checked by Robert Clark

how to charge an rv battery with a generator

There is no denying that the 12-volt RV deep cycle battery is one of the most critical components of recreational vehicles. From lights to water heaters, almost everything in your RV gets power from batteries.

So, as an RVer, it is essential to know how to charge an RV battery with a generator. It will be beneficial when you do not have access to shore power.

The good news is that charging deep cycle battery with generator isn’t a daunting task, and you won’t need professional help. Instead, what you need are some tools and a reliable guide, which we provide in this article.

Today, we’ll take a look at 7 simple steps to charge a 12 Volt battery, including:

  • Step 1: Plug in your generator
  • Step 2: Inspect the RV battery
  • Step 3: How to clean your battery
  • Step 4: Check out electrolyte levels
  • Step 5: Reconnect your RV battery
  • Step 6: Turn off the lights and unplug electrical appliances
  • Step 7: Plug your RV plug into a generator

Keep reading to see more!

7 Easy Steps to Charge an RV Battery With a Generator


If you want to recharge your house batteries using the internal generator, here is how to connect them properly:

Prepare the Necessary Things

Of course, you will need a portable generator to charge 12v battery. But you’ll need more than that to get the job done. Here are all the items you will need:

  • A wrench
  • Baking soda
  • Distilled water
  • A toothbrush and a clean rag
  • Petroleum jelly or battery rust protector

Step 1: Plug in your generator

First, it is essential to make sure you have fully charged your portable generator. It is possible to plug it into an AC outlet directly. We also recommend turning off your RV and engaging the emergency brakes to prevent accidents.

Step 2: Inspect the RV battery

Checking your RV batteries should be done periodically for cracking, bulging, and corrosion signs. Once you spot any fuzzy, green, yellow, or white stains on these batteries, it is essential to clean them. If your terminals and batteries are dirty, move to the following step. If not, jump to step 6.

Step 3: How To Clean Your Battery

Let’s begin by removing the cables using a wrench. You’ll need to remove the negative or black cable first, then the positive (or red) cable. Next, make a mixture of water and baking soda.

Use a toothbrush to apply this mixture to your battery terminals. A wire brush also comes in handy to eliminate corrosion.

Step 4: Check Out Electrolyte Levels

Since the RV batteries are not factory sealed, you have to check the electrolyte levels. If you notice the fluids levels are low, pour distilled water slowly until it hits the fill point.

Step 5: Reconnect Your RV Battery

Once your battery is as clean as possible, connect the battery component.

You will start with the positive (red) cable, then the negative (black) cable. Make sure the cables are well fastened.

Step 6: Turn off the Lights & Unplug Electrical Appliances

It is wise to unplug all electrical appliances to maximize the charging RV battery with generator. This is essential if your generator is wired directly to the RV’s electrical system. Also, it will help to shut off the lights.

It is always best to use your generator with a 120V AC outlet.

It is okay to plug the portable generator into a 12V C output. But the RV generator battery charging will be slower, and you will not charge the battery to its full capacity.

The temperature can also significantly affect the charging time of your RV battery. For example, charging RV battery with generator at a temperature below 40 degrees may limit the charge capacity.

So, we recommend parking your recreational vehicle or placing the battery and generator where the temperature is over 40 degrees.

Step 7: Plug Your RV Plug Into A Generator

Once your generator is properly plugged into an AC outlet, connect it to your battery.

Under excellent conditions, you can expect the charging to be completed in 2 to 4 hours. However, if your RV battery is depleted, it may take longer to charge fully. Avoid letting the RV battery go under 20% since this may reduce its lifespan.

Bonus Tips


  • Before purchasing a generator, check the specifications of your RV battery as RV batteries may differ in size, amps, battery discharge level, converter output level, and more.
  • Know how to stop the generator in emergencies.
  • Only operate the generator outside and at least three feet away from open vents, windows, or doors.
  • Read the owner manual and understand each of the receptacles and controls and all safety precautions for your vehicle.
  • If you use a portable generator to charge an RV battery, it is best to place your unit on a level and firm ground.
  • Check any cord you plug into your generator and replace them if damaged.
  • Replace your RV battery before it hits the expiration date.
  • Limit the usage of electrical items to save energy.
  • Clean the RV batteries regularly.
  • You should go with a backup power source in emergencies, such as when your generator runs down on energy.



1. How Long Does An RV Battery Last?

With regular care and maintenance, you can expect an RV battery to last five to seven years. When in use, you should check your RV battery every 30-days. Moreover, it is best to disconnect the battery when your RV sits idle for long periods.

2. What Should I Do When My Generator Do Not Charge The RV Battery?

In case your generator cannot charge the RV battery, you should:

  • Check out the water level and overall condition of your RV battery.
  • Make sure the main breakers on your generator are not tripped.
  • Ensure fuses are still good and the converter circuit breaker is on.
  • Check the battery to ensure it is not disconnected.

If you don’t have the skills to do it correctly or the time to spend on troubleshooting the RV’s electrical system, bring your vehicle to a trusted RV professional.

3. What Are the Fast Methods to Charge My RV Batteries?

The fastest way to charge RV batteries is by linking them to shore power.

Charging your RV battery with an alternator while on the go is a slower method. But it is possible to boost it up significantly by utilizing a DC to DC converter.

4. How long does it take to charge my RV batteries using a generator?

Your battery charge time will depend on the amount of charge required to supply it to a complete state. Also, it depends on the size of the battery charger. For example, a 10-amp battery charger should take longer to charge the RV battery than a 50-amp one.

5. Is It Possible To Charge RV Batteries Using Solar Panels?

The short answer is yes! It is an excellent pick to charge the 12 v batteries while on the go. It is especially beneficial if you own a “Two Way” fridge, and you need to operate it on electricity while driving your RV from one point to another.

A lot of hardware stores offer them for a cheap price tag. You can set it up in a south-facing direction, and photovoltaic cells will transfer charge to your RV battery.

The wattage produced by consumer-grade solar panels is relatively pretty low. As a result, it might take a day or more to charge a dead 12v battery fully.

6. Will My RV Batteries Charge When Plugged Into Shore Power?

Even when you plug your RV battery into a reliable shore power source, it can still die. But if you’re running your RV appliances strictly off shore power, the drain on your battery should be minimal.

Some entertainment facilities feature power inverters, allowing you to charge a 12 Volt battery off shore power directly. But this can take up to four or six hours, depending on the specifications of the inverter and the state of the battery.

Wrapping It Up

Hopefully, by the end of this article, you know how to charge an RV battery with a generator and do not have to worry about your RV’s battery being drained where shore power isn’t available. All you need to do is connect your batteries to the generator and wait a few hours for them to be fully charged.

Thank you for stopping by! Please share this article with other RVers.

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