One of the most critical components of your RV is the 12 volt RV deep cycle battery. Virtually everything in your RV from the lights to the water heater is powered by it. Since the RV battery is such an essential part of the vehicle, it is important to know how to reach full charge using a generator especially when you’re in the middle of nowhere with no access to shore power. Even if you have solar panels or wind generators installed to the roof of your vehicle, or reached full capacity with a battery charger, you may still encounter the risk of running out of juice if you have a short battery life, use a lot of energy, or don’t have enough sun or wind production. The easiest and most practical way to fill your battery when you are off-grid is with a fuel-powered generator. Generators can be used both as a power source for 120 volt outlets and a battery charger to fill up the batteries. Since it is a dual purpose unit and particularly useful in a pinch, we recommend everyone with an RV has a fully functional and charged generator in their vehicle to avoid a disruption or have to end their trip early to connect to a power source. 

While a portable generator is not the fastest way to charge your battery, it is the most useful especially when you are traveling off grid or unexpectedly loose power. We put together nine easy steps to charge RV batteries with a generator so you can quickly get back to enjoying life on the road with minimal unwanted disruptions.

Before you begin, be sure to follow all safety precautions for handling a 12 volt battery and portable generator. Make sure that all units are in safe, working order and inspect them for any damages or imperfections that may impact the unit’s functionality. When you are recharging your battery with a generator, perform these tasks in a well ventilated area and wear goggles and gloves to help prevent unwanted, potentially serious injuries. Additionally, it’s best to charge your RV battery when it’s not too cold and not too hot to ensure that it can hold the optimum amount of power. Always refer to the manufacturer’s instructions to help keep you and your loved ones safe when recharging your camper battery.

Before we get to how to charge your RV battery with a generator, we want to address some questions you may have:

Does running a generator charge an RV battery?

Yes, we recommend always having a generator on hand because it can be used in emergency situations as a charger for your RV battery. Although it can take a while to bring your battery back to full charge, if you’re in a tight spot, the generator can be a real lifesaver that will get your appliances back on so you can get back to having fun in no time. Having a generator as a backup, alternative power source will help ensure you don’t have to disrupt or end your adventures early and find a town or campsite to plug in.

What size generator do I need to charge my RV batteries?

Typically, a generator will need about a 3,500 watt capacity and 8 amp power to fully recharge your 12 volt RV battery. However, a generator with a 4,000 watt capacity can be useful in charging your battery more quickly. When charging RV batteries, it is important to monitor them so they do not over charge or overheat which could cause permanent damage to your battery. Be sure to check your battery specifications to make sure you select the best RV generator for your unit. 

What methods can I use to power my RV batteries?

You can charge your 12 volt batteries with an alternator, or using a generator, solar panels, wind generator, battery charger, or plugging it in to a shore power source. Each method has its pros and cons, so be sure to fully understand the pitfalls of each and determine the best solution to get your camper batteries fully charged especially if you tend to venture off grid.

How do I charge my RV battery with a charger?

Charging an RV battery with a three or five stage battery charger provides a fast and effective charge when connected to shore power or the electricity from your home. It starts charging the RV battery at a higher amp level until it reaches about 80% capacity at which point it transitions to a lower and lower amp charge to optimize the battery life until it reaches the maximum capacity and is fully charged. This type of charger is a great, long term solution for charging and maintaining your battery’s life during winter months or when you are not using your RV regularly. There are less expensive charger options that do not monitor the battery levels. While this is a great budget-friendly option, unless you keep a close eye on the battery charge level, the battery can become overcharged and may eventually become damaged or hold less juice. 

How long do I need to run a generator to charge RV batteries? 

The best answer: it depends. If your RV battery is down to 20% power, it can take up to ten hours to fully charge. Additionally, the capacity of your batteries, the output of your generator, how many appliances you have running, and the number of batteries you are charging all impact the amount of time it takes to fully charge your RV battery. If your battery is almost full, it could take just two hours to return to full capacity.

How often do I need to charge my batteries?

In general, you should be charging your batteries with a battery charger before you set off on your RV adventure. Using a charger before you venture out will ensure you have full access to your appliances and help ensure they are functioning properly. Once you begin to actively use the appliances that rely on your RV battery, you may need to charge it after about 20 hours of use. However, depending on the age and condition of your RV battery, you may need to charge it more or less than that. If you have a battery bank set up, it may require less frequent charges. Using a battery monitor and observing your  usage will help determine the best time to charge RV batteries based on your needs. 

How can I extend the power life of my battery?

By regularly cleaning and maintaining your battery and not overcharging it, you will ensure the battery is in the best condition and provide the maximum power time for your vehicle. If you want to spend less time charging, a battery bank can be a useful addition to your setup. A battery bank is two or more batteries that are connected to each other and provide more power to your RV than a single battery can provide. To safely bank batteries, the two batteries must have the same voltage and amp rating, be identical in brand and model, and be about the same age. 

When do I need to buy a new battery for my RV?

An RV battery can last a few years up to almost ten years depending on your usage and maintenance habits. To help keep your batteries in their best working condition and help potentially elongate their lifespan, avoid storing batteries in extreme heat or extreme cold, try and prevent the battery from fully losing its charge, and be sure to perform regular battery maintenance according to the manufacturer’s instructions. Depending on your maintenance schedule, usage, and the type of battery you have, the unit may last only 400 charges or up to 5,000 charges.

Here are nine simple and easy-to-follow steps to charge a deep cycle RV battery with a generator: 

  1. Before you set out on your RV adventure, make sure your portable generator has enough juice to fully charge your 12 volt RV battery (or to charge it enough until you can make it to another power source). Check to see if you need to top off the gas or oil level.
  2. Turn off your RV and engage the parking brake to help prevent potential injuries during the battery charging process.
  3. Unplug and turn everything off inside the RV. Doing this will help your battery charge faster and more efficiently because no appliances are using the power your battery needs. 
  4. From the battery, remove the black (negative) cable followed by the red (positive) cable.
  5. Check your RV battery for dirt, grime, cranks, leaks, corrosion, or any other potential issues. Clean away any foreign particles and make sure the battery is in a safe and usable condition. If it is damaged, be sure to repair it before using it again or replace it.
  6. Pop open the fill cap and check the battery’s electrolyte level and fill with distilled water to the fill line if needed. 
  7. Reattach the cables to the battery attaching the red cable first followed by the black. If necessary, use a wrench to securely refasten the cables. 
  8. Connect the RV plug to the generator to charge the battery.
  9. Be sure to monitor the battery as it charges to make sure it does not over charge which can negatively impact the battery’s performance or lifespan.

 

Do you have any tips on expanding the lifespan, charging, or maintaining your RV battery? We want to hear from you, so tell us about them in the comments.