Do AGM batteries need to be vented?

      by Phil Borges // in Articles

AGM stands for Absorbent Glass Mat, which is an advanced type of lead-acid battery that can be used for all your needs. It's spill-free and maintenance-free, meaning you won't have to worry about any spills or dirtying up the vehicle with grease as other types do.

Do AGM batteries need to be vented? The question of whether AGM batteries need to be vented is a big one. The answer, as it turns out, is both yes and no. It really depends on the type of AGM battery you're using. For instance, some AGMs require venting because they contain gases that can build up pressure if not released from time to time. These types of batteries are known as "wet cells" or "flooded." In contrast, other AGMs do not contain these gases, so there's never an issue with gas buildup at all. In these cases, there's no need for a vent.

Can AGM batteries be mounted inside?

AGM batteries can be mounted inside. Many manufacturers have designed their installation kits to accommodate mounting the battery in many different ways, as well as giving you a wide range of sizes and styles to choose from. All AGM batteries are hermetically sealed, so there is never any danger associated with venting them or charging them.

Traditional wet cell batteries can be harmful to your vehicle and the environment if they sulfate. AGM, on the other hand, is less reactive than its traditional counterpart because of how it works with chloride solution inside an alkaline lined container that holds calcium hydroxide electrolyte fluid (conventional battery types). You may mount these in any orientation without risk of corrosion or damage from moisture water content.

Do AGM batteries produce fumes?

These batteries are designed with the environment in mind, so they won't give off any fumes or emit harmful chemicals like other technologies can do. During charging sessions, chemical reactions occur inside of them, which produce gasses, most types released during this process stay confined within their own space. Still, with some older types of batteries, gases can leak outside, which is why vented containers were necessary.

They are commonly installed in sealed battery boxes or other enclosures that prevent the escape of hydrogen gas emissions. Additionally, these batteries have a very low internal pressure, so it is unlikely that any gases would ever vent from them unless there's damage or corrosion.

Are AGM batteries safe indoors?

AGM batteries can be used indoors. They are safe to use inside your home or office, similar to the way you would use a sealed lead-acid battery. You should not place them in an unvented location as this is bad for their life expectancy and general safety of usage. As long as they have enough ventilation space around them, you can store them indoors.

AGM batteries do not give off any gas (hydrogen) when charged, so there is less concern about ventilation because they don't produce toxic fumes like the old-fashioned zinc cells did.

AGM batteries do not require any special handling or maintenance. They are less likely to be damaged by overcharging than the more common flooded lead-acid cells because AGM's can withstand a higher charging voltage without damage. This also means that your battery bank will last longer with AGMs since you can charge them to a higher voltage, which means that the batteries will be less likely to sulfate and lose capacity over time.

Does AGM battery leak gas?

AGM batteries are sealed, so they do not need to be vented. The only difference between AGM and flooded batteries is that the gas produced by an AGM battery can escape through its valve rather than cause a dangerous explosion.

That's why you should not store your batteries in sealed compartments like the bilge, where they may build up explosive levels of hydrogen gas.

Remember that H2 buildup can have dangerous consequences for anyone who has placed a battery under a combustible surface or intends to charge one close to a flame source. Indeed, even though the exterior parts of an AGM battery are typically composed of synthetic rubber material that is insulated from the electrolyte fluid inside its container, which contains high levels of voltage electricity currents - those materials still present fire risks if they're exposed to heat or flame.

This is why it's extremely important to only charge the battery when you're in proximity and monitor its status while charging, especially during overnight use of a charger that emits heat or has exposed wiring.


It is vital that the battery does not overheat and should be kept in a cool place. Having a sealed battery that doesn't vent toxic gases into the environment makes it an excellent choice for many applications. If unsure of the battery's ability to vent, check with the manufacturer. They will be able to tell you if it is safe to use a sealed or vented battery.

About the Author

Hi, I'm Phil Borges.. thanks for reading.. My wife says I can't shut up about batteries so to save my marriage I've started this blog .. where I'd be ranting about batteries! Please leave a comment if you have any questions, I'm happy to help!