Like the rest of our equipment, we like to take good care of our RV’s batteries. However, there comes a time when even well-maintained batteries begin to lose their ability to hold a charge. That’s why knowing how to replace them is essential. In this post, we show you exactly how to do that, even if your battery bank has several batteries that appear to have a complex wiring configuration.
- 1) What Is an RV House Battery?
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2)
How to Replace Your RV Batteries
- 2.1) Take a Photo of Your Current Battery Bank
- 2.2) Draw a Diagram of Your House Batteries
- 2.3) Create a Tab on Both Ends of Every Cable
- 2.4) Turn Off All Power Coming to Batteries
- 2.5) Begin Removing the Cables
- 2.6) Disconnect the Main Negative Cable Leading to the RV
- 2.7) Disconnect the Remaining Cables and Remove the Batteries
- 2.8) Clean Your Battery Box and the Cable Ends
- 2.9) Install Your New Batteries
- 3) Step-by-Step Battery Replacement Video
- 4) How Can You Tell If Your RV Battery Is Bad?
- 5) How Long Should an RV Battery Last?
- 6) Can I Replace My RV Battery with a Lithium Battery?
- 7) Have You Replaced Your RV Batteries as a DIY Project?
What Is an RV House Battery?
As you may recall from our RV Battery Guide: House, Chassis, Lithium & More, the “chassis” battery (starting battery) starts your RV’s engine, while the “house” batteries power the interior lights, vent fans, water pump, and other 12-volt equipment. Through the use of an inverter (which converts 12-volts DC into 120-volts AC), they can also power your coffee maker, hair dryer, TV, microwave, and other household appliances.
One of the greatest things about RVing is the ability to travel widely with all or most home amenities handy. However, you need a working house battery bank for all of these amenities to function properly (especially when you enjoy boondocking the way we do). There are different types of 12-volt batteries, but our Battery Guide post can provide a detailed explanation.
It’s easy to be intimidated by the prospect of replacing batteries, especially if you’ve got a complex setup such as a bank of four or more 6-volt batteries wired in series-parallel. Just the sight of all that wiring is enough to tempt many people to walk away. However, as long as you follow a few simple guidelines and precautions, installing new RV house batteries can be a relatively easy DIY project.
Let’s show you how replacing RV house batteries is a manageable task that can ensure your power needs are met.
How to Replace Your RV Batteries
We were on the road full-time for 20 years, so we had to replace our RV batteries more than once. Our motorhome came from the factory with four 6-volt, flooded lead-acid house batteries wired in series-parallel, which is like having two large 12-volt batteries. When the time came to replace them, we installed four Lifeline AGM (Absorbed Glass Mat) batteries, also 6 volts, wired in the same series-parallel configuration.
The AGM batteries were more expensive but superior to traditional “wet” lead-acid batteries. They’re completely sealed, accept a charge faster, and perform better in every way. They’re also maintenance-free, so well worth the added cost. We later switched to the ultimate: lithium batteries, which, while even more expensive than AGM, worked incredibly well with our large array of solar panels (and when we sold that motorhome and bought our current travel trailer, the first big project we had done was the installation of a huge lithium battery bank and large solar array).
In both photos, you can see our chassis batteries on the left. On the right side of the top photo, you see our old flooded lead acid batteries, with the Lifeline AGM batteries at the bottom.
Regardless of what kind of batteries you choose, here’s how to replace them:
Take a Photo of Your Current Battery Bank
As with most projects, planning is a crucial part of the job. And among the most essential steps in the planning process is taking a photo of what you’re about to replace, so you’ll have a reference to look back on, should you need it. Take a clear photo of the top of your current battery bank so you’ll have a record of the wiring layout, allowing you to safely route the cables for the new batteries in the exact same way.
But a simple photo isn’t enough…
Draw a Diagram of Your House Batteries
Despite having a photo to refer back to, it’s best to draw a diagram of the layout of your house batteries as well. If your RV battery replacement project also includes your chassis batteries, be sure to include those in the diagram (Note: We were only replacing our house battery bank at that time, so our diagram included only those four batteries).
Create a diagram of the batteries you’re replacing. This will be VERY helpful during installation.
Number the batteries on your diagram, and be sure to include the battery posts, marking them as positive and negative.
Be sure not to skip this step. We know it’s tempting, but the diagram really is crucial, so take the time to sketch one out before you begin the battery replacement process.
Create a Tab on Both Ends of Every Cable
Use masking tape to create a tab on both ends of every cable on every post. We used a Sharpie to mark the tab for the negative post on battery #1 with a 1- (to indicate battery 1’s negative post).
We used a Sharpie to mark the tabs on the ends of each cable with a number corresponding to the appropriate battery and positive or negative post. Here you see we’ve marked the tab for the negative post on battery #1 with a 1- (to indicate battery 1’s negative post).
Next, we marked the other end of the same cable with 3-, to indicate battery #3’s negative post.
Here we’ve marked the tab for battery #3’s negative post with a 3-.
Note that each end of every single cable connected to a post gets labeled. For example, every cable end connected to battery #1’s negative post is labeled “1-“.
In this example, all cables that attach to battery #1’s negative post are labeled “1-“. You’ll do this with all cables on each battery’s positive and negative posts.
In this example, you see all cables attached to the positive post of battery #3 labeled “3+”.
Continue in the same manner, ensuring that you tag each end of every cable on every post. Did we already mention that? You’re darn right we did! If you fail to tag all the cables, you’ll know why we’re making a big deal about this when it comes time to reinstall everything.
If you plan to remove/replace your chassis batteries, be sure to tag and mark them as well.
Turn Off All Power Coming to Batteries
Before proceeding with this project (and before removing a single cable), ensure that all power sources to the batteries are turned off. Switch off the circuit breakers and unplug your power cord from the pedestal. Make sure your generator is off, and any solar panels are disconnected.
TIP: If you have solar panels but don’t have an on/off switch or breaker to disconnect the power, use towels to cover the panels to prevent them from sending power to the batteries, especially on a sunny day.
Also, turn off all power coming from the batteries inside the RV and at your battery disconnect switch(es).
Begin Removing the Cables
Using a socket wrench, begin removing the cables, starting with the main negative wire leading out to the RV. Be sure not to accidentally allow the ends of your socket wrench to touch a positive and negative post at the same time. Touching hot and cold terminals at the same time is dangerous and can cause sparks to fly, potentially leading to a fire or even an explosion.
Use caution when removing the cables, making sure the ends of your socket wrench never accidentally touch a positive and negative cable at the same time.
Using a socket extension is a good idea to keep the end of the wrench further away from the terminals. Better yet, wrap the entire handle of the socket wrench with electrical tape, which will insulate the metal handle and prevent it from completing a circuit.
Using a socket extension makes touching positive and negative terminals at the same time far less likely. Wrapping the handle with electrical tape is also a great idea.
Disconnect the Main Negative Cable Leading to the RV
Always disconnect the main negative cable leading to the RV first. It’s likely one of the thickest black cables in the bunch and will lead from the battery bank into the RV.
This is the main negative cable leading into the RV. It’s the FIRST one you should DISCONNECT and also the LAST to RECONNECT at the conclusion of the project.
The main negative cable is not only the first one to disconnect but also the last one to reconnect at the end of the job.
Disconnect the Remaining Cables and Remove the Batteries
Once you’ve disconnected the main negative cable, you can continue disconnecting the other cables one by one until they’ve all been removed from every battery. Then you can remove the batteries from the RV and set them aside.
Clean Your Battery Box and the Cable Ends
This is the perfect time to clean your battery tray. A paste of baking soda and water neutralizes battery acid. We also used a wire brush to remove loose paint and any rust, and then repainted ours with black Rust-Oleum paint. While the paint was drying, we used the wire brush to clean the ends of all the cable ends until everything shone like brand new!
- Wide, stainless stripper brush for removing rust and corrosion
- Safe to use with paint removers
- 12 pack, 14 oz. boxes of ARM & HAMMER Baking Soda Fridge-n-Freezer Odor Absorber
- FLO-THRU TECHNOLOGY: The only baking soda brand with Flo-Thru technology that has dual panel vents for maximum odor control
- Weather and corrosion resistant coating protects exterior/interior surfaces like wood, metal, concrete, masonry and more
- Oil-based formula provides a durable protective coating with excellent rust prevention
Install Your New Batteries
Place your new batteries into the RV, and connect all the cables in accordance with your diagram and the tags you created with the masking tape.
Remember to connect the main negative cable that goes into the RV last!
Note: If you’re installing regular lead-acid batteries, sliding a felt battery washer down over each post before reattaching the cable will reduce corrosion.
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Pangda 6 Pieces Battery Terminal Anti Corrosion Washers Fiber battery post shims Battery Terminal Protector battery corrosion cleaner (3 Red and 3 Green)
- Quantity: comes with 6 pieces battery anti-corrosion washers include 3 red and 3 green
- Features: the battery washers can prevent corrosion around the battery terminals, prolong battery life, for use with 6 and 12-volt battery
Finally, remove all the masking tape tags and turn the power switches back on.
We hope these steps, along with the accompanying photographs, have been helpful. But if you’d prefer a more visual tutorial, check out our video:
Step-by-Step Battery Replacement Video
How Can You Tell If Your RV Battery Is Bad?
It may be very easy to tell that your RV batteries are failing. Signs such as lights being dim or vent fans running more slowly than usual can be nagging indications that your batteries need replacing. To check the condition of your RV batteries, use a multimeter to test the voltage of each battery. Using a hydrometer, you can also check the specific gravity of the electrolyte in flooded lead-acid batteries.
Conduct either or both of these tests when the battery is fully charged and “at rest” (that means no power coming into the battery and no loads coming out).
- Backlight/Large screen LCD display/NCV/Live wire test
- MAX/MIN
- Professional Battery Tester
- Compact hand held tester reads specific gravity of battery acid
How Long Should an RV Battery Last?
The answer to this question depends on the type of RV batteries you have, how they’re used, and how well you maintain them. However, we can offer some generalizations:
- A well-maintained flooded lead-acid battery should last anywhere from 4 to 5 years.
- AGM and Gel batteries tend to last a bit longer, often in the neighborhood of 6 years or more. The Lifeline AGM batteries we had before we upgraded to lithium lasted us 7 years… and still had some life left in them.
- Lithium batteries have the longest lifespan (depending on the brand, they list between 10 and 20 years!), and often come with a 10-year manufacturer’s warranty.
Can I Replace My RV Battery with a Lithium Battery?
Although many lithium battery manufacturers advertise their batteries as “drop-in replacements,” that claim primarily refers only to the battery’s physical size. While they may be designed to fit into a standard flooded lead-acid battery’s space, other components of your rig’s electrical system are likely to require upgrading, such as the converter/charger, solar charge controller, and possibly other charging components.
This is the most of the equipment that MYT Solar installed for us as part of our new battery & solar system (the batteries are installed in the front pass-through compartment).
Even the system that takes power from your chassis battery and alternator to charge your house batteries while you drive may need to be upgraded. Therefore, you may be able to fit a lithium battery into the space where your lead-acid battery sits, but other factors also need to be considered.
To learn more, read “Everything to Consider When Switching Your RV to Lithium Batteries.”
Have You Replaced Your RV Batteries as a DIY Project?
Did you replace RV batteries yourself? If so, we’d love to hear about your experience and the type of batteries you chose. Leave a comment below with the deets!
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Jay
Saturday 7th of June 2025
If your battery tray has a slide out, you will obviously need to use it. After labeling all of the cables and before disconnecting any of them, takes some pictures of the layout at a few different angles. It's more than just reconnecting the same cables to the same posts. Their orientations need to be the same so that they won't interfere with pushing the battery tray back in.
Keep any washers, nuts or wing nuts from your old batteries just in case the new batteries don't have them.
I never saw any benefit from the red and green felt washers. I experienced the same corrosion with and without them. Increased corrosion can be a sign of a defective battery. While testing a wet battery's cells' specific gravity is inexpensive, reaching all of cells can be awkward at best. It requires sufficient electrolyte to pull up into the glass, testing cylinder and you're playing with sulfuric acid, which will damage your clothes. If you disconnect an individual battery's grounding wire, you can more easily check it with a load tester and you won't have to test every cell's specific gravity. The specific gravity battery testers are fragile and their rubber pipette hoses and the squeeze bulb get damaged from the battery acid.
If one of the batteries in your bank is bad, you will generally need to replace them all. You shouldn't mix types, sizes or ages.
Lithium batteries are completely different beasts. You can't just swap for them. The inverter needs to be compatible. You can discharge them to their full capacity (unlike lead acids, which can only be safely discharged to 50% of their listed capacity) however, more than that can permanently damage them. That's something to consider if your RV is not going to be powered for an extended time, such as when you drop it off for servicing. You need to have a disconnect switch for them.
Peter Shelley
Saturday 8th of June 2024
Perfect Timing! I need to replace mine soon. We just got back from 3 weeks in Barcelona Italy etc. Your Toad is running great. Thank you. I enjoy your columns. Peter
TheRVgeeks
Saturday 8th of June 2024
Hey Peter! So great to hear our trusty CR-V is still going strong! It’s the best all-around car I’ve ever owned. And we LOVE Barcelona! ❤️ Hope you’re having a great summer, and have an easy time replacing your batteries.
Bob Sunday
Sunday 8th of October 2023
Trying to find r-vision condor Coach battery location. Help!!
Ted E Phillips
Wednesday 21st of June 2023
Somewhat new to RVing .... I will be installing new Lithium batteries to replace my worn-out AGMs(2). I plan on going bigger to 200ah batteries(2) for a total of 400ah ...the unit is a 2001 Coachman class A with the WFCO Wf-9800 series converter/charger with a Progressive Industries 50-amp electrical management system. there is also a solar panel(1).
My question is, and I believe I know the answer is, will I need to replace my converter for it to recognize the Lithium batteries?
Thanks, Ted
TheRVgeeks
Wednesday 21st of June 2023
As a follow up, @Ted... found this thread about WFCO's "Auto Detect" feature: https://diysolarforum.com/threads/wfco-auto-detect-converter-does-not-auto-detect.45508/ Not sure if they've fixed/updated their units since this was an issue, but it doesn't sound like it's the best bet for ensuring your batteries stay properly charged if they're lithium. If you're going to upgrade the converter/charger, you may want to look into other options (like Xantrex or Victron) instead. They may not be drop-in replacements for what you have, but they'll do a better job keeping your lithium batteries healthy.
TheRVgeeks
Wednesday 21st of June 2023
Hi Ted,
Can't say 100% for sure on that, but it's quite likely you'll need to replace the converter/charger. The CURRENT version of the WFCO WF-9800 lists that it's Lithium compatible... but, assuming you have the original one installed back in 2001, we'd doubt that it was back then. So your best bet would be to try contacting WFCO (have the model and serial number of your unit handy) and see if they can advise you. You'll definitely want the answer to that before going ahead with the battery upgrade... so you don't risk damaging your new Lithium batteries.
Ben Benson
Saturday 10th of June 2023
Just a reminder, verify 6volt vs 12volt on your replacement batteries, when you soxument tour diagram and wiring set up, you can use 12volt in lieu of 6 volt but you have to wire them differently, i good idea, if your in a jam and cant locate 6volt batteries