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How to Store Your RV Batteries for Winter Without Damage

If you’re giving your rig a break for the winter, its important to know what to do with your batteries. Correct RV battery storage is crucial to prevent irreversible damage during the colder months.

If you’re wondering how to protect your batteries from damage, you’ve come to the right place. Below, we discuss how to store the various types of RV batteries in the winter, including which type of battery is easiest to maintain. Keep scrolling to learn more. 

Do Lithium Batteries Work In Cold Weather? Testing Lithium Vs Lead Acid in Freezing Temps

Why it’s Important to Properly Winterize Your Batteries

RV batteries are the heart of your RV’s power system and are expensive to replace. If you don’t correctly care for them during winter storage, they can suffer from many issues, like freezing, sulfation, and self-discharge, that will permanently damage them. 

rv battery storage in the snow
Here is an image from my security camera of our RV stored for the winter in 10 degree temps. What did we do with the batteries?

Freezing Electrolyte Damage

A lead-acid battery can freeze if the temperature drops significantly, especially if the battery is weak or discharged. The freezing point of the electrolyte within a lead-acid battery varies depending on its state of charge:

In a fully charged lead-acid battery, the electrolyte is primarily sulfuric acid, which has a much lower freezing point than water. Typically, the electrolyte in a fully charged battery will not freeze until the temperature drops to around -70°C (-94°F) or below.

As the battery discharges, the sulfuric acid is converted into water, which increases the freezing point of the electrolyte. In a fully discharged state, the electrolyte’s freezing point is approximately the same as that of water, 0°C (32°F). Therefore, if a discharged lead-acid battery is exposed to freezing temperatures, the water content in the electrolyte can freeze.

When the electrolyte in a battery freezes, it can expand and cause physical damage to the battery’s internal structure, including cracking the battery case or breaking the internal plates. Such damage is often irreversible, leading to a significant reduction in battery performance or complete failure.

Self Discharge

Batteries naturally self-discharge over time, and this process can accelerate in cold conditions for some battery types. If a battery self-discharges too much and is left in a deeply discharged state, it can lead to sulfation in lead-acid batteries or a reduced lifespan in lithium-ion batteries.

Damage To Anode And Cathode

In lead acid batteries that self-discharge, the plates can become sulfated. In deep discharges, the lead plates react with sulfuric acid in the electrolyte to produce lead sulfate and electricity. This is a normal part of the battery’s operation. However If the battery is not recharged in time or let to sit, the lead sulfate can begin to crystallize and harden on the battery’s plates. This crystallization is what is known as sulfation. This reduces the surface area of the plates, reducing contact area and battery performance, causing permanent damage.

Deep discharges do not inherently damage Lithium Ion batteries, but charging in temps below a certain point can cause lithium dendrites to form. At low temperatures, the electrolyte’s conductivity decreases, and lithium ions do not move as freely or evenly, exacerbating the uneven deposition that leads to dendrites. These dendrites reduce surface area like sulfation, resulting in capacity and performance loss. However, they can also cause catastrophic failure if they reach far enough to pierce the seperator and short the battery out.

Different Batteries Have Different Requirements

RVs typically use different battery types, each with a set of storage requirements. The most common types are flooded lead-acid batteries, absorbed glass mat (AGM) batteries, and lithium-ion batteries. Understanding the specific needs of your RV batteries is crucial for ensuring they remain in optimal condition during the winter.

Winter rv battery storage
We tested lead acid vs lithium in simulated freezing temperatures

Lead-acid and AGM can lose charge quickly, even without connecting to a power drain. This is the self-discharge rate, and it can be as high as 20% per month for lead-acid batteries. In contrast, lithium-ion batteries have a self-discharge rate of about 3.5% per month. In addition, as mentioned above, lead acid batteries can freeze solid and destroy themselves if they become too discharged, so it’s essential to keep them charged. With lithium, making sure there is no drain and completely disconnecting them is the better choice.

Pro Tip: Prepping for some winter weather? Find out Do Lithium Batteries Fail In Cold Weather?

How to Properly Store RV Batteries Over the Winter

Let’s take a look at the three methods I recommend to store your RV batteries.

1. Keep The Charger Running All Winter (Lead Acid)

In most cases, you should store your RV batteries at full charge. A charged battery is less susceptible to freezing, and it minimizes the risk of sulfation. If your RV has a built-in battery charger or maintainer, we highly recommend using it to keep the batteries topped up during storage.

Alternatively, you can invest in a quality battery charger/ tender for long-term maintenance. The charger can ensure a constant trickle charge to keep the batteries in good condition. This is especially crucial for lead-acid batteries, as they have a much higher rate of self-discharge. 

**Warning- If you have cheaper lithium-ion batteries that do not have low-temperature cutouts, leaving the charger on can destroy them. Even with low temp cutout we recommend method 2 for lithium ion as the cutout might stop charging and allow full discharge.

2. Disconnect From All Power Drains (Lithium or no power available)

If you cannot provide power to keep the batteries charged, they must be fully charged, then disconnected. This is true for all RV batteries because even the smallest drain can kill the batteries. As mentioned before letting batteries sit dead, especially in the cold is the worst thing for them.

The best way to do this is with a battery switch. As long as you’ve installed it correctly, a flick of this switch should completely disconnect all potential power drains from the battery. It’s also crucial to ensure there aren’t any electronics bypassing the battery switch. 

If you don’t have a battery switch, you can always disconnect the negative terminal of the battery to prevent residual drain from parasitic loads. This will ensure that your battery experiences only the natural self-discharge rate. 

Ideally, a battery tender or even a small solar trickle charger can keep them topped off. Regardless always make sure the battery is fully charged before disconnecting.

** Pro Tip – If you have solar panels, be sure to disconnect them from the charge controller when you disconnect the batteries. Otherwise its possible that the controller could try to power the electrical system without the battery and cause problems.

3. Remove The Batteries Completely

If you will be storing in extremely cold temps below -20F regularly, you might want to remove the batteries completely and store them somewhere with higher temps. Freezing is ok, but extreme cold can cause damage to all battery types. We personally have never done this, but the coldest we experience is around -10 for a brief time.

batteries removed for winter
If you want to do the best thing for your batteries, pulling them out completely and storing them above freezing is best, but a lot of work!

For Flooded Lead Acid, Make Sure Fluids are Topped Off 

Compared to lithium-ion batteries, lead-acid batteries require much more maintenance. Flooded lead-acid batteries require special attention to the electrolyte levels. Before storing your RV for the winter, check the fluid levels in each cell and top them off with distilled water if necessary. Be careful not to overfill, as the electrolyte expands during charging. Overfilling can lead to leakage. Maintaining the correct fluid levels helps prevent the plates from exposure, reducing the risk of sulfation and enhancing the battery’s longevity.

Pro Tip: Curious to know what battery fairs best in the winter? We tested multiple RV batteries to determine which one is the best of the best.

How Long Can You Store Deep Cycle RV Batteries? 

The duration of RV battery storage depends on various factors, including the type of battery, its state of charge, and environmental conditions. Lead-acid batteries are designed for regular discharge and recharge cycles. However, if you properly store them, they can typically retain a safe charge for several months. This is especially true if you use a battery charger or tender. 

RV parked in snow
Proper storage can help you avoid having to replace your batteries every year.

In the right conditions, lithium-ion batteries can be stored for up to 10 years. If you’re storing them for long periods, it’s crucial to store them in a cool and dry environment, away from direct sunlight. The ideal state of charge for lithium batteries is around 75%, but they will discharge at a percentage or two per month.

Avoid Replacing Your Batteries Each Year with Proper Storage

Correctly storing your RV batteries for winter is vital. The last thing you want is to discover your batteries need replacing when you’re ready to hit the road. By disconnecting from all power drains, fully charging the batteries, and checking and topping off fluid levels for flooded lead-acid batteries, you can avoid the pitfalls of improper storage. Remember, investing in the care of your RV batteries will pay off. You’ll have reliable power and a longer battery lifespan when you’re ready to travel in the spring.

Do you have any questions about how to store your RV batteries in the winter? Drop them in the comments below!

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About Tom Morton

Tom, a Pacific Northwest native, is our technical genius. Born in Washington and raised in Alaska before settling in Michigan. He's the man who keeps our operation running, both figuratively and literally.

With a background in Electrical Engineering, Tom specializes in RV solar systems and lithium batteries. He made history as the first documented individual to use a Tesla battery module as an RV battery. Tom has personally assisted countless RVers with system installations and has educated thousands more through his videos and articles.

Cinematography is another of Tom's passions, showcased in his work on the Go North series. You can see his camera skills on display in The RVers TV show on Discovery Channel and PBS where he also stars as a co-host.

Tom's mechanical expertise extends beyond RVs to boats, planes, and all things mechanical. He's renowned for taking on maintenance and repair projects single-handedly and is often spotted underneath RVs, making him the technical backbone of our endeavors.

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Dr. Mike

Friday 15th of March 2024

Your article is very well written, but focuses on a cold winter climate. Here in North Florida, our “winter” is around 45 degrees and our camper is kept in a climate controlled garage with electric to keep the batteries fully charged. We do your suggestion #1, but have 8 AGM batteries. We have not had any issues in past winters.

Paul Sklut

Wednesday 13th of March 2024

I’ve heard that if you have a solar panel and you remove your batteries the controller for your panel may be damaged. It’s my understanding that the power from the panel to the solar controller should be disconnected wherever the batteries are removed. The other option would be to cover the panel(s). Is this true?

Tom and Caitlin Morton

Thursday 14th of March 2024

Well, I have seen this done a few times and while I have not seen controller damage, It does very weird things to the circuit. When the load exceeds the panels output the controller usually goes into an under voltage condition and switches on and off rapidly which can actually damage other things in the system. So Yes, disconnect the solar panel (via switch, fuse or physically) before disconnecting batteries. I forgot to mention that in the article but will add it!