Is It Safe To Use a Battery Tender In a Closed Garage?

Is it safe to use a battery tender in a closed garage

Have you ever wondered if is it safe to use a battery tender in a closed garage?

Battery tenders are much loved by the motoring community for ensuring that the batteries inside of their vehicles are kept topped up, even when the vehicle is not being used for long stretches of time. This often occurs around the winter months, particularly with RVs.

However, anybody that has ever used a battery tender will likely notice a massive warning in the instruction manual saying that it shouldn’t be used in an enclosed area.

Some people may even have heard horror stories of batteries ‘exploding’ when using a battery tender for long periods of time.

Is it safe to use a battery tender in a closed garage? Yes, it is safe to use a battery tender in a closed garage. However, they have put those warnings in the battery tender’s instruction manual for a reason.

On this page, we want to talk a little bit about whether it is safe to use a battery tend in a close garage and, if it isn’t, what you can do to ensure that using the battery tender is safe.

Is It Safe to Use a Battery Tender in a Closed Garage?

Not many people realize this, but when a battery is charging, gases will start to build up around the battery. On one side of the battery, you have oxygen being produced. On the other side of the battery, you have hydrogen being produced.

In a normal situation, the production of these gases won’t be that much of an issue. When your car is running, they will be whisked away pretty quickly.

However, when your vehicle is connected up to a battery tender, you don’t have that ‘luxury’. Instead, all of those gases are building up in an enclosed location, and they aren’t going anywhere.

Now, if you had the garage door open, the air would flow in and blow gases away from that battery. However, if the door is closed, there is very little airflow.

Basically, you will have an explosive gas combination scattered around an explosive battery. Even the smallest of sparks can send it up in flames.

As long as you have proper air flow into your garage and around the battery, then there shouldn’t be any issues having a battery tender in a closed garage.

However, if you have no ventilation around the battery, then it is pretty much a ticking time bomb, and you will need to do something about it. 

Read also: How Safe Are Battery Tenders?

How Can You Ensure That the Battery Tender is Well-Ventilated?

In an ideal world, you would have your garage door open. However, we are going to assume that you are keeping your vehicle inside because it is a bit cold outside.

Our suggestion is to ensure that, at the very minimum, air can flow around the battery. This may mean that you need to pop the hood to expose the battery contacts. Although, ideally, the battery wouldn’t even be in the vehicle at all.

You would keep it separate, just in case there is any sparking.

You should have a small fan set up in your garage pointed directly at the battery. Make sure that this fan is on for at least a couple of hours per day. This should help to prevent gases from building up around the battery.

Obviously, it is not going to be preventing those gases from building up completely as that would go against basic chemistry. However, it should ensure that the gases are dispersed around your garage to the point where they will not pose any problem.

If you cannot get a fan into your garage for some reason, then you could always bring the battery inside of your home.

Obviously, it is going to be taking up a bit of space and a battery tender can make an awful sound, but at least you won’t have to worry about the battery exploding on you!

Every couple of days, we suggest that you open up the garage door for 10-15 minutes. This will allow fresh air to flow in and disperse those gases a little bit better.

This isn’t going to be strictly necessary if you are only charging a small battery, but you may as well try and reduce the risk as much as possible, right?

Should You Do Anything Before You Take a Battery Off of the Battery Tender?

If you have been keeping the battery area well-ventilated, then there isn’t much that you need to do. It is unlikely that there will be any sort of gases floating around the battery.

However, since there is still a small risk, and eliminating that risk takes mere seconds, you may as well do a bit of preparation before you disconnect everything.

We are going to assume that you have already switched off the battery tender. If you haven’t done that, then do this first. Remember, with the battery tender on, that battery is going to be generating those gases.

Now, head to the battery. However, before you disconnect anything, you will want to fan around the battery with a newspaper. This will help to disperse the gases and ensure that it is safe to disconnect everything.

There are some people that haven’t fanned their batteries properly, and some haven’t even turned off their battery tender first. The problem with doing that is you will likely cause a bit of sparking when you disconnect the clips from the battery.

Remember what we said before? It only takes a small spark to ignite those gases. The battery inside of a vehicle could kill you if it explodes.

How Long Can a Battery Stay Connected to a Battery Tender?

There is no danger in having the battery tender hooked up to the battery forever. In fact, there are some people that will have their batteries hooked up to a battery tender all year. It is not dangerous at all, as long as you ensure that the area is properly ventilated.

The main issue that you will have is not so much whether the battery tender is going to cause the battery to go up in flames, it is more the fact that the battery life will be drastically reduced when it is hooked up to a battery tender.

Remember, batteries only have a limited number of charges on them before they start to falter. A battery tender will be constantly charging the battery which, of course, means that the lifespan of the battery will be drastically shortened.

In our opinion, you probably wouldn’t want to have the battery tender hooked up to the battery for short periods of time. We would only recommend that the two are connected up if the battery is going to be left unused for at least a month or two.


While it isn’t advised, it is safe to use a battery tender in a closed garage. However, if you want to guarantee that your battery isn’t going to randomly explode due to a build-up of gases, it is vital that you have some sort of ventilation flowing around the battery.

A fan should be all that you need here. If you do not do that, then you run the risk of losing your battery or your vehicle. In fact, a serious explosion and subsequent fire could cost you your home. 


Mike Gilmour

Hi, I'm Mike, co-founder, and editor of RV and Playa. My passion is traveling (with my RV) and enjoying the day at the beach (Playa)! Well, I originally created this blog as a way to share what I've learned by experimenting with the RV lifestyle, and I want to help others develop in life through new skills and opportunities.

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