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Should I Disconnect My RV Battery When Plugged In?

John Marius
John Marius
—
16/01/2024

In the world of recreational vehicle (RV) ownership, understanding the ins and outs of proper battery maintenance is crucial. One common question that often arises among RV enthusiasts is whether they should disconnect their RV battery when the vehicle is plugged in.

In this article, we will delve into the pros and cons of disconnecting an RV battery while it is plugged in, providing you with the necessary insights to make an informed decision.

Is it Harmful to Keep Your RV Continuously Plugged in?

In general, the answer is no, especially with modern smart chargers now being standard in most RVs.

Most RVs manufactured in the last decade, whether a travel trailer, fifth wheel, or motorhome, include an integrated converter. This component not only manages power distribution but also converts the Alternating Current (AC) from shore power or a generator into the essential 12V Direct Current (DC) for charging the batteries. Additionally, it actively oversees and regulates the power supplied to the batteries, effectively protecting them from overcharging—a potential threat that could significantly reduce battery lifespan.

Related reading: AC VS DC, What are the Differences

ac vs dc

To confirm if your RV includes a built-in converter, ideally with a float mode, consult the provided manual or look up the model number for your power distribution panel. If your RV lacks this feature, we can explore alternative methods to ensure your batteries remain charged without overcharging.

For short periods of time (say a month or less), generally, it's acceptable to leave the RV plugged in.

However, for long-term storage, especially if your RV has an old or inefficient converter/charger that could lead to overcharging, it may be necessary to disconnect the RV battery to prevent damage.

If you store your RV for an extended period, particularly in very cold temperatures, consider completely disconnecting the house batteries and possibly storing them in a warmer location for the winter.

Potential Issues with Keeping Your RV Continuously Plugged into Shore Power

Keeping your RV continuously connected to shore power isn't as simple as it seems. While modern lithium RV batteries are equipped with advanced battery management systems, prolonged, unattended charging can damage your battery and electrical components.

When an RV battery is constantly connected, three main problems can occur:

  • Overcharging: Modern converters with smart charging capabilities can reduce this risk, but older systems may continue to push current, causing battery fluid evaporation and premature degradation of internal components.
  • Sulfation: Batteries that remain in a charging state for extended periods can develop sulfate crystal buildup, reducing the battery's capacity and lifespan. This subtle damage often goes unnoticed until there is a significant drop in performance.
  • Thermal Stress: Continuous charging generates heat, which accelerates battery aging and can cause electrical system failures, especially in older RV models or extreme temperature conditions.

Does the RV Battery Charge While Connected to Shore Power?

Yes, charging an RV battery via shore power relies on two crucial factors that many RV owners often overlook.

First, check if the battery disconnect switch (typically located near the battery in a compartment or nearby) is set to "off." If it's off, the batteries won't charge until you turn the disconnect switch on. Surprisingly, many RVs are brought into dealerships due to this simple oversight. Often, new RV owners are unaware of the in-line disconnect that needs to be activated.

Next, ensure that your RV is receiving sufficient shore power to meet all power requirements and still have leftover capacity to charge the batteries. For example, if a small 1500 Watt generator is running your RV, and heavy power draw appliances like air conditioning and a hairdryer are simultaneously in use, there might not be enough power left over for the converter to charge the batteries.

Fortunately, modern converters are automatic and seamlessly redistribute power to the batteries when there's a break in power draw, requiring no manual effort on your part.

Can an RV Converter Function without a Battery?

This topic is heavily debated online. To test the converter's performance, follow this simple procedure.

First, connect the recreational vehicle to shore power. Next, turn on various twelve-volt systems, such as lights and water pumps. Finally, disengage the battery disconnect switch.

You may notice that most twelve-volt systems keep working even without a battery. This finding challenges the common belief that a battery is essential for most 12V electrical components in an RV.

However, there is an important exception to keep in mind. Some electrical motors, especially those for slide-out mechanisms, may struggle without a battery. The issue arises from how a power converter and a battery supply power. While a converter delivers a steady current, high-demand motors need a burst of power that only a battery can provide.

Keep in mind that slide-out functionality can differ greatly between RV models. Manufacturers usually offer clear guidelines on operational needs. To find specific requirements, owners should check the original documentation or look for informational stickers near the slide-out controls on their RV.

Engaging in Electrical or Appliance Maintenance

Whenever you undertake maintenance in your RV, whether it's replacing a light fixture or servicing the water pump, it's important to pull the fuse for the circuit and consider using the battery disconnect. Not only does this action protect you in the event of an electrical mishap, but it can also help prevent costly issues in the long run. This simple precautionary step is vital for the safe and efficient maintenance of your RV.

Proper Use of an RV Battery Disconnect Switch

Alternatively known as: What is this component, and when should I use it?

An RV battery disconnect switch is a crucial feature for any vehicle with a house battery. A single action (often a twist) allows you to swiftly and easily disconnect the main RV circuit from the battery, safeguarding not only the battery itself but also other electrical components of your RV.

battery disconnect switch

Usually located near the battery in its compartment or in a nearby maintenance bay, this switch is often overlooked or even forgotten, hidden behind various items inside a storage bay.

Batteries tend to discharge slowly over time, even when the appliances they're connected to are turned off. Even in the off position, electrical appliances draw small amounts of energy passively in anticipation of startup. Wiring itself also gradually drains power. This type of energy loss leeches at least some charge from your battery and can ultimately lead to a dead battery precisely when it's least expected or needed.

When to Utilize an RV Battery Disconnect

Understanding the appropriate times to use an RV battery disconnect is essential for all RV owners. When dealing with electronics, it's crucial to take proper safety measures to avoid causing damage or risking injury. Here are key times to use the RV battery disconnect:

litime battery disconnect switch 

During Long-Term Storage

If your RV will sit for weeks or months, turn off the disconnect switch. This stops parasitic loads—small power draws from devices like smoke detectors and clocks—from draining the battery. It helps keep the battery charged and healthy during periods of inactivity.

While Performing Maintenance

When you work on your RV, such as changing a light fixture or servicing the water pump, always pull the fuse for that circuit and use the battery disconnect. This protects you from electrical accidents and avoids costly problems. This simple step is vital for safe and effective RV maintenance.

To Prevent Overcharging

If your RV lacks a built-in converter with a float mode, use the disconnect switch when plugged into shore power for long periods. This helps prevent overcharging, which can damage the battery and shorten its lifespan.

To Protect Against Power Surges

In areas with unstable power, disconnecting the battery while on shore power can protect it from damage caused by surges.

Using the battery disconnect switch at these times ensures your RV’s electrical systems work safely and efficiently.

Storing Your RV without Shore Power

If your RV will be unused for more than a week or two and lacks the option to connect to shore power (even a standard 15A household circuit is sufficient to maintain the batteries), it's important to disconnect the batteries. Doing so minimizes current loss caused by excess wire runs and appliance trickle.

Using a 7-Pin Receptacle on Your Tow Vehicle

If your RV possesses a 7-pin connection to your tow vehicle, one of the pins provides charging power for your RV leisure battery. While this capability helps recharge your house batteries during trips, it can also lead to issues.

Leaving your RV plugged into your tow vehicle for an extended period (hours) without the tow vehicle running can result in draining the vehicle battery to charge the RV batteries.

Certain vehicles automatically shut off the power to that pin when the ignition isn't on, whereas older models often lack that function.

What to Do If Your RV Doesn't Have a Built-in Float Charger?

If your RV doesn't come with a built-in float charger, you can consider using an external battery charger or a separate float charger like MPPT solar charge controller and DC-DC charger. External battery chargers can be connected to your RV's battery when it's not in use. A float charger, also known as a battery maintainer, is designed to keep a battery at its fully charged level without overcharging, making it an excellent choice for maintaining RV batteries during periods of inactivity. Please keep in mind that the battery maintainer is not suitable for lithium batteries.

When choosing an external charger or float charger, ensure that it is compatible with your RV's battery type (e.g., lead-acid, gel, AGM) and that it provides the appropriate charging voltage and current. Additionally, verify that the charger has features such as automatic voltage regulation and overcharge protection to ensure the safety and longevity of your RV's battery.

Conclusion

In conclusion, for RV owners, the dilemma of whether to keep batteries connected while plugged into shore power used to be a significant concern due to the limitations of older technologies. However, advancements in RV battery technology have made this decision much easier.

LiTime's deep cycle RV lithium batteries are designed with low self-discharge rates, ensuring minimal power bleed when left connected. This feature simplifies maintenance and reduces hassle, making it easier for RV owners to manage their power systems. This advantage becomes especially apparent when returning from extended periods away from your RV, as the batteries retain their charge better than traditional lead-acid options.

To learn more about the experiences of LiTime users and to stay updated on the latest news, consider following LiTime on Facebook.

Frequently Asked Questions

1. Should the battery disconnect switch be on or off when plugged in?

The battery disconnect switch should generally be on when your RV is plugged into shore power. This allows the converter to charge the battery and supply power to 12V systems. However, if your RV will remain plugged in for a long time and lacks a smart charger, it’s wise to turn the switch off to prevent overcharging. Always check your RV's manual for specific recommendations.

2. Should the RV battery be on when connected to shore power?

Yes, the RV battery should typically be on when connected to shore power. This ensures the converter can maintain the battery's charge and power essential 12V systems like lights, fans, and control panels. If your RV doesn’t have a built-in float charger, keep an eye on battery levels to avoid overcharging. Refer to your RV's manual for best practices tailored to your setup.

3. How can I tell if my RV battery is overcharging?

Signs of overcharging include excessive heat from the battery, swelling, or a strong sulfur smell. Additionally, if your battery voltage exceeds the manufacturer’s recommended levels, it may be overcharging. Regularly checking the voltage with a multimeter can help you monitor the battery's health.

4. What happens if I leave my RV battery connected while not in use?

Leaving your RV battery connected while not in use can lead to parasitic drain from devices like clocks and alarm systems. This can deplete the battery over time. Using a battery disconnect switch helps prevent this issue.

5. Can I use my RV appliances while plugged into shore power?

Yes, you can use your RV appliances while plugged into shore power. The converter will provide power to your appliances and charge the battery simultaneously. Just make sure your electrical system can handle the load of the appliances you are using.

6. How often should I check my RV battery?

It's a good practice to check your RV battery at least once a month, especially during long periods of inactivity. Look for signs of wear, check the water levels (for lead-acid batteries), and monitor the charge status to ensure optimal performance.

John Marius
John Marius
John Thompson, an automotive engineer with 15+ years of EV and lithium battery experience, holds a Master’s in Electrical Engineering from Stanford. He’s passionate about advancing battery tech and promoting green energy.

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