How to Charge RV Battery With Generator

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In this article we will explain how you can charge the batteries of your recreational vehicle (RV) with a generator. We are referring to the larger and more complex 12 volt household batteries, which are often grouped together rather than in individual units. These batteries are what power household appliances when they are not connected to the ground.

The most common type of household battery is a 12-volt flooded lead acid battery, also known as a wet deep cycle battery, which as they charge and discharge, release gases through the caps. These batteries need regular maintenance, including replacing lost water and keeping them above 50% charge for optimal life.

Despite the above, they continue to be popular due to their balance between price and performance.

Charging your 12-volt RV or camper batteries with a portable generator is fairly simple, and it provides two options. The first involves the use of a battery charger connected between the RV's batteries and the generator. The second is to connect the RV directly to the generator.

List of Necessary Items (Tools Needed)

Before interacting with your RV batteries in any way, make sure you have the proper equipment:

  • Insulated Gloves
  • Safety Goggles
  • Pliers
  • Wrenches
  • Screwdrivers
  • Insulated Tools
  • Insulated Gloves
  • Safety Goggles

Before you Charge the RV Battery

There are two different ways to charge your RV batteries: the first is simpler but it is also the slowest method. The second is a bit more complicated, but it is faster. However, before proceeding to charge the batteries, do the following safety and maintenance steps.

  1. Turn off your RV and set the emergency brake.
  2. Locate the 12 volt (or 6 volt) batteries. The location and voltage may vary from one model to another. Consult your owner's manual if you are unsure.
  3. Make a visual inspection of the battery; check for cracks, bulges, or corrosion. Corrosion can shorten battery life and must be cleaned.
  4. If you notice that the battery is bulging, remove it from service immediately. Don't try to charge it!
  5. Remove the cables from the battery terminals taking care that no metal bridges the terminals.
  6. Using a mixture of baking soda and water, scrub the terminals to remove dirt. Use a small wire brush to remove traces of corrosion. Allow the battery to dry before starting to charge.
  7. Finally, unscrew the battery cover and check the liquid level. If it is below the full line, add distilled water until it reaches the line. If your battery has a "Maintenance Free" label, skip this step.

First method: plug in the RV

We already said that this may be the slowest method, as it requires powering the entire electrical system of your RV or caravan. You can run all your appliances this way, but it will slow down how quickly you can charge the RV.

If your RV was manufactured before the mid-2000s, the battery charger built into your system may only provide a trickle charge.

Important Note: Make sure the generator is compatible with your RV's power systems. RVs with 15A and 30A plugs should run on any generator that produces 120V power. If your RV has a 50A plug, you will need a more powerful generator.

Step 1

Give your generator a full charge or plug it directly into a shore power AC outlet.

Step 2

Double check the battery connections to make sure they are free of corrosion. If they have any yellow, green, or white fuzzy stuff on them, you will need to clean it with some wet baking soda and an old toothbrush.

Step 3

If you don’t have a factory sealed battery you should try checking the levels of electrolyte. If you the fluids are low you can slowly pour a small amount of distilled water until it reaches the fill line. Then reconnect the battery components and tighten down the lid.

Step 4

If your generator is directly wired into your RV’s electrical system, you want to turn off all lights and appliances to make sure as much potential charge as possible is going toward charging the battery. Also keep in mind that temperature can be a factor. If the ambient air temp is below 40-degrees, it can limit the maximum charge the battery can hold. If possible, try to move the generator and battery or park the RV somewhere over 40.

Step 5

Plug the RV generator in and connect it firmly to the battery. In ideal conditions you might be able to charge it up within two to four hours.

Second method: portable battery charger

This method is a bit more complicated, but the load is faster. It involves using the portable generator to connect a three-stage portable charger. These chargers automatically adjust and reduce their power to avoid overcharging the battery.

By choosing to connect the battery charger to the generator, you speed up the charging process, save money on fuel for the generator, and reduce pollution.

Step 1

If your RV has a battery disconnect switch, turn it to disconnect it from the electrical system. We do this to ensure that when we turn on the generator, we are not sending electricity to appliances or anything plugged in.

If you're not sure whether your RV has a battery disconnect switch, check your owner's manual. If not, make sure the batteries are disconnected from the system before connecting the battery charger.

Step 2

Locate the home batteries in your RV. This is different for every vehicle, the owner's manual should be able to help. Perform a visual inspection for corrosion or signs of damage.

Step 3

Fill your generator's fuel tank and start the generator. Let it run for about 3-5 minutes.

Stage 4

Plug your battery charger into the portable generator. Check the status lights to make sure they are working properly.

Step 5

If charging only one RV battery at a time, remove both cables from each battery. Start with the negative (-) cable. Then remove the positive (+) cable. Make sure the terminals do not touch any other metal.

Connect the black negative (-) cable from the battery charger to the negative (-) terminal of the battery. Next, connect the red positive (+) lead from the battery charger to the positive (+) terminal on the battery. When the battery is fully charged, go to the next one.

If you fully charge a battery bank at once, consult your owner's manual. There are different settings, and your owner's manual should provide precise instructions for your situation.

Tips And FAQ’S

1. How Long To Charge RV Battery With Generator?

It can take 12 hours to get from 50 to 100 percent in boost mode. A lead acid battery takes much longer to charge than discharge. If you have the charge wizard dongle you can manually control the mode. So if you manually put it in boost mode you may have to change it back to normal mode manually. 

2. Does running a generator charge an RV battery?

Generators are not specifically designed to charge an RV's on-board 12 Volt Batteries. Ideally, you want to use a smart charger, which is plugged into your home's electricity or an RV parks shore power. 

3. Can you use a generator to charge solar batteries?

Solar Panels offer a green solution, though usually charge slower than using a portable generator. Additionally, cloud cover could inhibit the power flow from the solar panels when charging RV batteries. Many modern RVs use a combination of generator and solar panels to charge, depending on the situation.

Safety measures to consider when charging RV batteries

DO NOT allow the two terminals of a battery to bridge with other metallic bodies. This can cause serious damage to the battery and yourself.

DO NOT allow the positive leads of a battery to touch metal. If they are still connected to the battery, it will start to discharge electricity into the metal. This can cause serious injury, death, or damage.

ALWAYS inspect your RV battery before performing any maintenance or charging. Watch for bumps, cracks, or any other signs of damage. If you see any of these, immediately remove the battery from service and replace it. Clean corrosion before putting the battery back into service.

ALWAYS charge your battery in a well-ventilated area when using a battery charger. During the charge cycle, your battery can produce toxic gas during its charge cycle, which can quickly build up to toxic levels.

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