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Does an RV Battery Need to Be Vented?

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Last Updated on September 20, 2022 by Jessica Lauren Vine

Are you asking, “Does an RV battery need to be vented?”

Most modern RVs have at least one battery to power the DC circuits and appliances when the RV is not connected to shore power. Depending on your RV’s battery, it will need to be properly vented. Determining if your specific battery needs to be vented is fairly simple. Let’s look at the different batteries you can use to power your RV and their venting needs.

Flooded Lead Acid Batteries

Flooded lead acid batteries are the least expensive and most common batteries found on new RVs. These old-school batteries have removable caps that allow you to add distilled water to the battery cells periodically. The need to add water is due mainly to the hydrolysis of the water during the battery’s charging process.

When current is applied to charge the battery, the water in the cells is split to form oxygen and hydrogen gasses. If you remove the caps while charging, you will see bubbles coming to the water’s surface in the cells as this process occurs. The caps must include breather holes that allow the hydrogen and oxygen to escape into the surrounding air to prevent pressure build-up from that gas production within the battery.

Hydrogen is a highly flammable gas and can be explosive when confined in closed quarters. For this reason, any flooded lead acid battery in your RV must be properly vented. Proper ventilation will allow the hydrogen gas to be safely dispersed into the surrounding area, significantly reducing the risk of fire or explosion.

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Sealed (Maintenance Free) Lead Acid Batteries

Most modern car batteries are filled with electrolytes (the liquid that bathes the plates inside the battery), and then the access holes at the top are sealed with a non-removable cap. These “maintenance-free” batteries don’t require you to add distilled water periodically during the battery’s life. Maintenance-free batteries also emit hydrogen while charging, albeit much lower than their flooded lead-acid cousins. Even so, these batteries should also be vented when used in your RV.

AGM Batteries

AGM stands for absorbed glass mat, which refers to the internal construction of the battery. 

Unlike flooded or maintenance-free lead acid batteries, the liquid inside the battery is not free to slosh around in the cell. Instead, a glass matting material absorbs the electrolyte to keep it in place. These batteries are more expensive than the lead acid batteries discussed above, but they have several advantages. First, they tend to last longer and require little to no maintenance. Their biggest advantage is that they do not generate gas while charging. Therefore, AGM batteries do not need to be vented.

Gel Batteries

Gel batteries are similar to their AGM cousins in that the electrolyte inside the battery is not free to slosh around inside the cells. However, instead of using a glass mat to bind the electrolyte, an additive must be added to convert the electrolyte into a thick gel. The result is essentially the same. These batteries also do not emit gas while charging and do not need to be vented.

Lithium-Ion

The newest batteries commonly used in RV are lithium-Ion batteries, most commonly LiFePO4 – or lithium iron phosphate batteries. These batteries are much larger versions of those commonly found in rechargeable cell phones, computers, and tablets. They are a completely different design than the batteries listed above and have no liquid components in their construction. These batteries do not emit flammable gasses as you use them, so they do not need to be vented in your RV.

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Determining Which Batteries You Have 

Flooded lead-acid batteries are usually the easiest to identify. They will have removable screw caps on the top to add water. They should also be labeled somewhere on the case noting that they are flooded with lead acid batteries. Maintenance-free lead acid batteries, AGM, and Gel batteries will all look very similar. 

To differentiate them, look for labeling on the case that notes they are “AGM” or “GEL”. If you don’t see that, play it safe, assume they are lead acid maintenance-free batteries, and vent them. Lithium-Ion batteries will all look different from the other styles and will also look different from each other based on the manufacturer and model of the battery. This battery type should be marked on the case as Lithium or LiFeP04.

Does an RV Battery Need to Be Vented? – Other Considerations

Venting is just one thing to consider with batteries. Keep in mind that this store’s much energy which can be released to disastrous results if not properly maintained. Because venting is not required, don’t install your batteries into some enclosed RV corner that you can’t easily access. Maintenance-free batteries still need to be maintained, and you should have routine battery checks as part of your RV maintenance schedule.

Before you head off, make sure you check out these other RV-related articles.

How Far Can You Drive an RV In a Day?

How Do I Maintain the Outside of My RV?

What Can I Use to Clean the Outside of My RV?

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