Why and How RV Batteries Need to Be Vented?

How are RV batteries vented

Does your RV have proper battery ventilation? If you are not sure, or not even sure what that means then this is an article you need to read now, before you head off on your next trip! The fact is that battery ventilation is very important, as we’ll now explain.

RV Battery Basics

Most common RV battery types – lead acid, gel cell and AGMs – produce a gas, hydrogen, that is explosive. Which is fine, as long as the gas remains sealed in the battery. If you have ever left a spent AA or AAA battery in a device for a long period of time you may have seen it leak. And had the vapor pressure built up enough, or, as is the case in the video below it is overcharged, it could have exploded.

AA batteries are tiny. RV batteries are not. That’s why, if you take a take a closer look, you’ll see that battery manufacturers attach a warning notice to their batteries that stresses the importance of proper battery ventilation.

In some cases, if a battery is overcharged it will produce hydrogen. And hydrogen has no color and no smell. Unsealed batteries do emit a smell, but that smell is not hydrogen. Without proper instrumentation, a hydrogen leak is undetectable.

If a battery is overcharged it starts ‘boiling‘, and will produce lots of hydrogen. If that hydrogen is allowed to reach a 10% buildup the battery may explode. Or, if it leaks out, the tiniest spark can ignite it. RV battery ventilation prevents these nasty scenarios.

The Overcharging Issue

The average RV battery can handle a small amount of overcharging. But not very much. If your RV battery is properly ventilated and ‘boiling’ occurs – and it is away from any possible source of ignition – the potentially dangerous hydrogen will dissipate away harmlessly into the air. 

But, and we can’t stress this enough – that will only happen if you have taken the issue of battery ventilation seriously.

What is RV Battery Ventilation?

Why you should vent RV batteries

Although it sounds fancy, and rather technical – venting an RV battery is not quite as complex as it sounds. All you really need to do is add a few holes – about 25mm in diameter to the top and bottom of your battery enclosure. It’s a simple enough procedure and it could prevent a disaster.

What’s the best way to make those holes? 

A drill is the most efficient way to do so as it is relatively quick and easy. A handheld drill is probably easiest to ease, as you will be able to get to just the right spots more easily.

Some people may have noticed that there are a number of specialist vented RV battery boxes available for sale these days. Do you need one of those? Maybe. 

The old vent-it-yourself method is still viable, some people do prefer to purchase and install one of these instead.

If you chose to do so, you will need to make sure the vented battery box you choose is large enough to accommodate your battery comfortably (not too tight, not too loose) and that you will be able to install it in the spot where your RV battery is right now.

Why Do Some Say You Don't Need to Vent RV Batteries?

You will, if you spend enough time around other RV enthusiasts, or in enough RV forums, encounter people who say that RV batteries really do not need to be vented. This is not advice we would suggest you listen to.

It’s true that the risk of an explosion is small. As long as your RV battery is in good shape, it will keep any hydrogen produced by an overcharge safely enclosed in the battery. But battery explosions do happen, and it’s such an easy thing to do, why would you take the risk?

Do I Need to Vent Lithium-Ion RV Batteries?

Lithium-Ion RV batteries are one of the newest options for RV owners, and those who have made the switch, or who are considering doing so, may wonder if they need to vent these batteries.

Lithium-ion batteries do work in a different way to any other. We can actually let NASA do the explaining for us here:

It would be very unusual for a lithium ion RV battery to be damaged by a little bit of overcharging, and if it were to be damaged, it would immediately give off a lot of smoke, just as is the case in this video. It’s hard to fail to notice here that something has gone very wrong (or in this case right, as it was the intention of the demonstrator).

So, although the explosion is rather different to the one in the first battery explodes video as you can see, you – and your RV will still benefit from the battery box that contains it being vented, and we suggest that you still do so. 

The Importance of Checking Your RV Battery

Even if you have vented your RV battery you should inspect it occasionally. As an RV battery ages, as is the case for a standard car battery, its clamps and connectors may loosen and, in the case of the connectors, crack. Over time this may mean that you are adding a fire hazard as a single spark could ignite slow escaping hydrogen. Again, it is rare, but it can, and sometimes does, happen.

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