Rankedgenerators is audience-supported. When you buy through links on this site, we may earn an affiliate commission that we use for site maintenance. Learn more


How to Charge an RV Battery with a Generator: Detailed Guide

How to Charge RV Battery With Generator
Written by Jamie Masterson

If you are out camping and your RV battery runs out, recharging it with a generator can be the easiest way. There are a 120-volt AC battery, a 12-volt DC system, and 6-volt RV batteries used for the additional home appliances like bulbs, fridges, and other devices.

You can take your RV battery as a power source for your camping or outings as they tend to supply power for a long time with a steady flow of current.

Using a generator is not actually the ideal way to charge an RV battery. However, if any other source is not available, you can still manage to charge your RV battery with the generator by following the steps below.

How to Charge an RV Battery with a Generator: Step-by-Step

How to Charge an RV Battery with a Generator


  • Recharge the Generator

First of all, the generator needs to be recharged to function as the power supply of a steady current for the RV battery charger. You need to double-check the gas or oil level. If it’s empty then full it to the tank’s ‘full’ level.

Now connect an electrical outlet to the generator to recharge fully. You can start the generator a few minutes before to get it started. If you are confused about the procedure, make sure to check the battery’s guiding principle that comes with it.

  • Clean the Battery

You need to clean your RV battery before you charge it. Look for any dirt, or yellow or green rusty stuff on your battery by removing the cable wires. When you are removing the cables, always remember to pull out the negative cables (black) first then the positive (red) ones.

If there is any dirty part, take a piece of cloth to dust off the dirt. Then mix baking soda with water and use a toothbrush to get into the parts to clean them. Rub till it is clean. Don’t forget to dry the area before plugging it in.

Before the cleaning process, turn on the emergency brake mode and switch off the car to avoid an unnecessary accident.

  • Prepare the Battery

At this step, prepare the battery for recharging by checking the electrolyte level. Pour distilled water in the battery to the “full” level. You should not charge your battery when it is running on a low liquid.

Next re-plug the cables into its terminals. This time attach the positive wire then the black one.

Now subjoin the battery alligator clips to the socket. Pin the red clip with the plus signed terminal and the black clip with the minus signed terminal.

  • Unplug Other Devices

You should unplug any other device that might drain your battery during the charging process. Connect the battery to a 120-V AC outlet.

If you want to fast charge your battery, unplug any device, or light bulbs that are sourcing power from the battery. This will help minimize the charging time and maintain longevity for your battery.

Another thing that impacts your battery’s charging time is the outside weather temperature. The battery will not charge to full aptitude if the temperature is or above 400C.

  • Plug the Battery

After everything is set up, plug the battery with the generator to recharge. Use a three-stage charger to the plugin. This keeps the current flow steady and does not do any harm to the battery.

It will take 2-3 hrs to recharge depending on the generator. It might take longer for a full charge if the battery was fully drained.

Discharge when fully charged.

Tips & Cautions

  • While charging the battery and the generator both produce gas such as hydrogen and deadly carbon mono-oxide. So it is important to charge the batteries in an open or ventilated place.
  • Use goggles and gloves while cleaning the battery to protect from dust or acid burn.
  • Keep flammable liquids, hand sanitizer, rubbing alcohol, and gasoline far away during cleaning and charging the battery
  • Rub Vaseline around the clean terminals to keep corrosion from forming very quickly
  • Charge your RV battery every 3 months to retain from your battery plates to get harden.
  • Do not touch the battery while charging.
  • Charge your battery to “FULL” to get better output and long-lasting battery health.
  • Monitor your charger so that it does not over-charge which might end up ruining the battery’s overall performance.
  • Do not store RV batteries in cold places. Batteries will not be able to store power and will supply less power if kept at a low temperature.
  • Before starting to charge, always double-check the red and black wires. If they get misplaced it can cause great harm.
  • Also if the batteries do not start charging after plugging in, then there might be a problem with the converter or the wire.


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

Ans. To charge a 12v RV battery, a generator should be of 3500 watts capacity and 8 amp. It can be more than 3500 watts which will allow charging the batteries faster. But a 3500 watt is also good to go.

2. Is It Possible To Charge An RV Battery Directly From Shore Power?

Ans. One of the easiest ways to charge a 120V AC RV battery is to connect it with the shore power. You will need a 30-amp or 50amp plug to connect the battery to the charging point. After you plug it in, it will automatically start charging.

3. Can I Charge My RV Batteries With Solar Panels?

Ans. Charging RV batteries with solar panels is a good option to explore. The power supplies through the solar panel to the amp controller or the charge controller to the battery.

An amp controller assists the battery in not overflowing with charge.

The key factor in charging your batteries with a solar panel comes down to understanding the right charge controller. The amp of the charge controller has to be higher than the combined amp of the solar panels and battery.

Divide the solar panels’ watt capacity with the volt power of your battery bank to know the amp of the charge controller.

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

Ans. If your RV battery has broken terminals or cracks on the case, it is high time to replace your battery. A deep-cycle battery should give service for more than 6 years. Depending on the maintenance and utilization of the batteries, an RV battery can last longer than that.

About the author

Jamie Masterson

With decade-long experience as a generator technician, Jamie has worked with USA’s top generator manufacturers and suppliers as an independent contractor.

The long years of service to the industry has taught Jamie the ins and outs of troubleshooting, repairing, and maintaining all kinds of generators in home, industrial and outdoor settings.

Jamie thinks this platform is a great opportunity to share his tips and tricks with you so you can make the most of such power equipment for better living.

Leave a Comment