Can a 9-volt battery start a fire in an RV?

In a word, YES. So let’s explore why, and under what circumstances.

Can a 9-volt battery start a fire in an RV?

In a word, YES. So let’s explore why, and under what circumstances.

But first, a short personal story about why I know this. Perhaps 25 years ago I was doing a big sound gig outside for the Maryland Symphony Orchestra on the 4^th of July. So it was hot, sunny and I was crawling around on stage setting up 60 microphones.

Some of my wireless mics used standard 9-volt batteries, just like the ones you’ll find in most smoke detectors and many transistor radios. You know the ones that look like a little rectangular cube with a pair of contacts on the top. And those contacts are uninsulated, which is why I literally had hot pants that day.

You see, I had stuffed a new 9-volt battery in my pocket along with some loose change. I didn’t think about this until I noticed my leg feeling hot. At first I assumed it was the hot sun beating on my leg since I was laying on the stage under some chairs running cables.

But the heat soon got unbearable and I reached down to feel my pants, which were REALLY hot. When I jumped up I noticed my jeans were smoking. Yes, literally hot pants. What had happened was the 9-volt battery in my pants was shorting out on the quarters in my pocket and was now too hot to touch. A few more minutes and my pants could have caught on fire. Of course the other guys in the crew thought it was pretty funny, and I was amused if a little burned.

So why did this happen and can it happen to you?

Well, a standard 9-volt battery has a lot of energy in it. After all, it can power a smoke detector for a year or more and run a transistor radio for dozens of hours. And if that energy is released quickly, it converts into a lot of concentrated heat. So any metallic object bridging the terminals on the top of the battery will create a short circuit which quickly causes the cells inside the battery to overheat.

Normally when these batteries are sold they’re packaged so the terminals can’t contact anything metallic. And professional battery packs include a plastic cap that insulates the terminals from making contact with anything conductive.

But throw a 9-volt battery in your junk drawer and anything metallic can accidentally come in contact with the terminals as your RV is driving down the road. If that occurs, you can have a fire start inside your RV in a few minutes, and there’s few things more scary than a fire in an RV, especially if you’re driving down the interstate.  

Keeping Safe

What to do to keep safe? Well, many industrial-duty batteries like I use have a little plastic keeper on the top. This prevents them from shorting out.

If you don’t have a plastic keeper on your battery, then a simple wrap of electrical tape over the top of the battery will protect it from short circuiting and catching on fire.

Let’s play safe out there…. Mike