Does an RV Battery Charge When Being Towed?

To make this concept easier to understand, consider an RV battery as a flat tire. As you all know, greater air pressure is required to fill up to inflate the flat tire. If, however, the pressure is less, the tire will simply push the air back out. Similarly, as the battery approaches maximum capacity, the charge is pushed back. 

How are RV Batteries Charged

A battery can be charged in various ways. The important aspect is to check that the battery is being charged. You may need an RV battery monitor for this. Note that a fully-charged 12V battery will output 12.6 volts or more, while a half-charged battery will put out between 12.06 to 12.1 volts (NOT 6 volts).

For now, let’s take a closer look at some of the ways your RV battery can be charged.

Converter-Charger

A converter takes AC power and converts it into DC power. This is one of the basic ways to charge an RV battery. So while your RV is plugged in, the charger/converter system converts the 120v shore power into 12V DC power, allowing the battery to store energy.

In fact, 55 amps of DC can easily provide power for all the RV lighting and appliances.

Inverter

Class A RVs typically have an Inverter-Charger. They work in the opposite way of a converter-charger. An inverter increases the voltage coming from the DC power supply (the 12V battery) and changes it into AC when there is no shore power. 

Single Stage Chargers  

These are found in low and mid-range trailers and smaller RV battery chargers, especially older ones. A fixed voltage is applied, so initially, there is a lot of amp flow at first. However, the constant voltage causes the charging rate to decrease as maximum capacity is reached. 

Multi-Stage Charger 

A more modern method of charging is used in the multi-stage charger. This approach focuses on optimizing battery charging by breaking down the process into three stages: Bulk, Absorption, and Float.

The Bulk stage is when a battery promptly charges on a low charge till it reaches about 80% capacity. The battery is constantly charged at 25% of amp capacity. 

As the battery begins to push back the charge after 80%, the charger increases the voltage in order to keep the amps at a constant rate.

During the Absorption Stage, voltage is maintained to about 14.1 – 14.8 volts to allow the battery to reach its maximum charge capacity. The last stage, or the Float mode, helps keep the battery fully charged at 100% by maintaining a voltage of 13.6V. 

Charging an RV Battery While Towing

An RV’s battery can also be charged directly through the tow vehicle’s alternator when the RV motor (or tow vehicle) is running. This is how cars typically charge their own 12v batteries. The same concept applies to charging your RV’s house batteries.

Mechanical energy is generated every time you start the engine, and a belt rotates the alternator. The alternator converts this mechanical energy into electrical energy, helping to charge the batteries.

While this is great for extended road trips, it’s not ideal for people camping in one spot for a lengthy period. That would require you to idle your vehicle so that the batteries are charged. This not only is this inefficient, but it’s also bad for your vehicle.

Alternatively, RV batteries can be charged with solar power, wind power, or when you’re running your generator.

How to Effectively Charge RV Batteries While Driving

The house battery runs the electrical components in your living space when the RV isn’t plugged into shore power. An RV battery bank charges while you are driving, allowing you to use your RV without an electrical hook-up or gas generator. 

However, this is true if you have a 7-way connector wired to your vehicle’s starting battery. The trailer battery gets a small trickle charge while you are driving. Because the amount may not be too large, it may not necessarily be an effective way to charge.

You can use a 12V feed to charge the RV battery while driving. Furthermore, you must install a battery isolation solenoid that allows this line to be disconnected when the tow vehicle is off.

Otherwise, the trailer battery could end up draining the tow vehicle’s battery. More importantly, you need to use a wire gauge heavy enough to allow the charging current to pass through to the trailer battery. Consider using a minimum of a 10-gauge wire.

Final Thoughts

Remember that your RV battery will charge while you are towing as long as the motor of the RV or tow vehicle is running.

It’s also important to ensure proper charging protocols for your RV’s battery if you want it to last.

Routine maintenance, recharging discharged batteries as soon as possible, and avoiding overcharging can help extend the life of your RV battery.