The Ultimate Guide to Charging an RV Battery: Tips and Techniques

Keeping an RV battery fully charged is vital to ensuring a smooth and enjoyable trip. A fully charged battery will power important appliances and keep your motorhome running efficiently. So whether you’re an experienced RV owner or a newcomer to the RV world, knowing how to properly charge your RV’s battery can save you time and hassle.

In this general guide, you’ll discover everything you need to know about RV battery charging, including the different methods available, step-by-step instructions, and best practices to ensure your battery stays in tip-top shape.

Understanding RV Batteries

What Are RV Batteries?

What is an RV battery? In simple terms, an RV battery is the electrical source of supply for all electrical systems in a motorhome (RV). There are two types of batteries typically found in drivable RVs:

• Starting Batteries (also known as chassis batteries). This is the battery that starts the RV engine and powers the lights and other electrical systems while the vehicle is running. These batteries are similar to car batteries but are designed to be more durable and provide consistent power over a longer period of time.
• Household Batteries (deep cycle batteries) are used to power appliances and other electrical systems when the caravan is not connected to shore power. They are usually connected in parallel to increase capacity.

RV Battery Types

The three most common types of caravan batteries are available are flooded lead-acid (FLA), absorbed glass mat (AGM), and lithium (Li-Ion). Each type is suitable for use in motorhomes, but each has its unique advantages and disadvantages.

Flooded Lead Acid (FLA) Batteries. FLA batteries are tried, tested, and readily available, making them a good choice for customers on a budget. However, they require regular maintenance, including monitoring water levels. They can also spill or leak acid and are slightly less efficient than AGM or lithium batteries.

Absorbed Glass Mat (AGM) Batteries. While similar to FLA batteries in some ways (they are both lead-acid batteries), AGM batteries are sealed, maintenance-free, and more resistant to shock, heat, and overcharging. They also have a slightly higher energy density, which means they can store more energy in less space. Although AGMs are more expensive than FLAs, they have a longer lifespan.

Lithium-ion batteries (Li-Ion). Li-Ion batteries are the newest batteries available and are a good choice for customers who need a high-performance, lightweight, long-life battery. Li-Ion batteries can handle deep discharge cycles and high charge/discharge rates. However, the disadvantages are that they are more expensive than lead-acid batteries and require special charging equipment.

Battery Specifications

Volts or voltage (V)
Volt is the amount of energy given to an electronic circuit. For example, by circuit, we mean an electronic device. For 12V devices, the battery always “delivers” 12 volts. Batteries always have a fixed voltage (e.g., 12 volts, 24 volts, or 6 volts), and devices always operate at a certain voltage. For example, a device that operates at 12 volts needs a battery that also provides 12 volts.

Current – Amps (A)
When we talk about amps (or amperes), we are talking about how much electricity “flows” per second. If the amperage increases, so does the current flowing through the device per second. Electrical equipment usually operates at a fixed voltage, but the number of amps it draws will vary depending on factors such as the location of the tow engine.

Power – Watts (W)
Power is voltage multiplied by amperage, i.e. W = V x A. This is the amount of energy consumed by the device and therefore an indication of how powerful the device is. As the amperage goes up, so does the power.

Capacity – Amp Hours (Ah)
Battery capacity is measured in Ah or Amp Hours. As the name implies, this means how many amps the battery can put out in an hour.

For example, a 12-volt lithium battery with a capacity of 100Ah will provide 100 amps of current to a 12-volt device in one hour. The same 100Ah battery will power a 25 amp device for 4 hours (100/25=4). If a battery has a voltage of 12V50, it means that the battery operates at 12 volts and has a capacity of 50 ampere-hours. 24V100 battery operates at 24 volts and has a capacity of 100 amps, etc.

In reality, the nominal capacity of a lead-acid battery (how many amp-hours the battery can deliver according to the specifications) varies greatly from the effective capacity (how many amp-hours the battery can deliver during use).

Capacity – Watt-hours (Wh)
Another measure of battery capacity is watt-hours (Wh). Watt-hours are calculated by multiplying the battery voltage by the number of amps. For example, a 12V100 (a 12-volt battery with a capacity of 100Ah) has a capacity of 12 x 100 = 1200 Wh. A 24V50Ah battery has a capacity of 24 x 50 = 1200 Wh. So, these batteries have the same capacity except that one operates at 12 volts and the other at 24 volts. You will find that these batteries are about the same size and weight.

Cycles
The number of complete charge and discharge cycles a battery can undergo before its capacity drops significantly.

5 Different Options to Chargig RV Batteries

There are several different ways to charge an RV battery, and here are four safe and effective ways to do so:

• Shore power
• Generator.
• RV or trailer alternator
• RV solar panels

Next, we will talk about how to charge your RV battery using each of these methods. The following information applies to 12V deep cycle RV batteries.

Shore Power

Plug the RV into shore power.You can use grid power to charge your deep cycle RV battery. There are two ways to do this. The first is to plug the RV’s power cord into a 120V AC outlet at your campground. Your vehicle should have a converter that converts AC to DC so that your battery can be charged.

Another way to charge via shore power is to use a battery charger. Ideally, you’ll want to purchase a charger that matches the type of battery (lead-acid, AGM, lithium) for optimal charging. Some Lithium Smart chargers can charge lead-acid, AGM, and lithium batteries.

Always check the compatibility of a charger before using it on your RV battery. If you use the wrong charger, one of three things will happen. You’ll get snail-speed charging, no charging at all, or worst case scenario: you’ll damage the battery.

Which battery charger do we recommend? If you have a lithium battery, the smartest choice is a smart battery charger like this one. Your caravan battery will be fully charged in no time.

Pros:

• Convenient access to grid power at campgrounds.
• Can charge the battery quickly if using a suitable charger.
• Compatibility with various types of batteries (with the right charger).

Cons:

• Requires access to a power outlet or campground hookup.
• Relies on external infrastructure, which may not be available in remote locations.

Generators

There’s another easy, albeit noisyway to charge your RV battery. Some RVs are equipped with generators. You can also purchase a portable generator.

If your generator has a 120V outlet, simply plug in the RV’s power cord as you would with shore power. If it has a 220V outlet, you will need a converter. Be sure to follow the safety precautions explained in your generator owner’s manual, such as checking fuel levels and air filters.

Pros:

• Provides a reliable power source, especially in off-grid locations.
• Can charge the battery relatively quickly.
• Offers flexibility for charging in various environments.

Cons:

• Noisy operation, which can be disruptive in quiet camping areas.
• Requires fuel (gasoline or propane), adding to operating costs and environmental impact.
• Maintenance and upkeep of the generator are necessary.

Vehicle Alternator

Another method is to charge your RV battery while you’re on the road. But don’t expect a lightning fast charge! Your battery will only get a little charge when you use a tow vehicle (like a truck) and an alternator to charge it. If you need more than just a little, you’ll need to add a charger.

Pros:

• Charging occurs while driving, allowing for continuous replenishment of the battery.
• No additional equipment or setup required, as it utilizes the vehicle’s existing electrical system.

Cons:

• Charging rate is limited and may not fully replenish the battery during short drives.
• Adds strain to the vehicle’s alternator, potentially impacting fuel efficiency.
• Not suitable for extended periods of stationary camping.

RV solar panels

What’s the most environmentally friendly way to charge your RV battery? Solar power! You can use flexible solar panels on your RV roof and portable solar panels to charge your RV when you stop for a break.

But using solar power isn’t as complicated as it seems. We previously wrote an article on the difficulties of installation, and you can follow the tips in the article to hook up solar panels to RV batteries.

Pros:

• Environmentally friendly, using renewable energy from the sun.
• Silent operation, without noise or emissions.
• Provides a continuous trickle charge, even when stationary.
• Solar panels will protect your RV battery,  they can maintain the RV battery by charging it regularly, preventing it from being damaged when it sits idle for long periods.

Cons:

• Upfront installation costs can be high, although long-term savings may offset this.
• Effectiveness depends on sunlight availability and positioning of the panels.
• Limited charging capacity during overcast days or in shaded areas.

How to Charge an RV Battery: The Basics

Once you’ve decided what method to use to charge your RV battery, these general guidelines will ensure that your battery stays in good condition.

1. Make sure your batteries are kept clean, no matter what type they are. Water, oil and dirt can cause self-discharge and short circuits.
2. Install your battery charger in a clean, easily accessible place.
3. When you want to charge your RV battery, park your RV in a level area and apply the parking brake.
4. Remove the cables from the battery leads. (Negative terminal first, then positive).
5. Remove sulfation and add distilled water if necessary (lead acid batteries only).
6. Connect battery charger cable to battery (or converter cable). (Positive terminal first, then negative).
7. Plug the charger or converter into a power source.
8. If you have a smart lithium battery charger, you can check the charging status on your cell phone via Bluetooth. The indicator light on the charger will show when the battery is done charging.
9. Turn off the power and disconnect the battery.

RV Battery Charging Safety Tips

So now that you know which charging option is best for you, you should know how to ensure the safety of these rechargeable batteries. Here are some guidelines to ensure safety:

• Regardless of which battery you use, the battery should be kept clean. If there is water, oil or even dirt on the batteries, it may cause these batteries to discharge without any trigger, causing a short circuit.
• Never forget to charge the batteries using a charger that is clean and has access to the batteries.
• When you are ready to charge your caravan, you should park it on a level road. Only charge the caravan when the parking brake is on.
• In addition, before starting to charge the caravan, the cables should be removed in order. The negative cable must be removed first, then the positive cable.
• If you are using lead-acid batteries, you must always clean the sulphates and add distilled water.
• Make sure that only the charger cable is connected to the battery. Also, don’t forget to connect the positive cable first and then the negative cable.
• If you have a small lithium battery charger, you can also browse the battery status on your mobile phone. You can connect the charger to your mobile phone via Bluetooth.
• When the charger’s indicator light is on, the battery is fully charged.
• Once the battery is fully charged, you can switch off and disconnect the battery from the mains.
• When using lead-acid batteries, be careful of battery sulphation and clean the battery before charging. In addition, lead-acid batteries should always be kept in a ventilated area. However, this does not apply to 100% maintenance-free lithium batteries.
• When using a battery charger, choose one that is compatible with the battery, e.g. there are different chargers for lithium batteries and different chargers for lead-acid batteries.
• When charging a battery via a solar panel, always use a charge controller, which prevents the battery from being overcharged.
  Never charge a frozen battery. Although you can use RV lithium batteries below freezing, charging an RV battery below freezing can cause plating or crystallisation. This crystallisation can weaken the battery.
• You should also be careful of high temperatures when charging your battery and never use your battery at temperatures above 50 degrees centigrade.

If you use any other power source to charge your caravan, always read the specific instructions for each product first. This way, you can avoid any safety issues and keep yourself safe from any type of electrical accident.