3 Things to Know About Smoke Detectors and Batteries


A smoke detector is a typical piece of kit for the modern American home. Nearly every home has at least one; many homes have two or more. We install them because we know they save lives. To the extent that batteries power our smoke detectors, you could say that batteries are life-saving devices as well.

How much do you know about smoke detectors and batteries? If your knowledge is limited, you are about to learn three things you might not have otherwise known. Just remember this: a smoke detector has to be in proper working order to do what it is designed to do. It is not enough to have smoke detectors installed on the ceiling. They have to be working smoke detectors.

1. Why Batteries Last So Long

Perhaps you have noticed that smoke detector batteries last a long time. It is not unusual to install a battery and not have to think about it again for more than a year. Other electronic devices in your home go through batteries like they were nothing. What’s the deal?

Most of the consumer smoke detectors now on the market work on one of two technologies. The first is ionization. This technology features two electrically charged plates that create a current running between the two of them. The current is the result of ionized air. Smoke disturbs the ionization and disrupts the current, triggering the alarm.

The other technology is photoelectric. Instead of current and ionized air, it relies on infrared light. Light moves from a transmitter to a receiver. If that light is disrupted by smoke, the alarm is triggered. In both cases, the components do not require much electrical current to keep working. Infrared light and ionization are both low energy technologies.

How Often Batteries Need Changing

Next up is the frequency with which batteries need to be changed. There is no hard and fast rule in terms of battery life. A good lithium-ion battery, like the one sold by Utah-based Pale Blue Earth, could easily last a year or longer. Experts prefer we not let them go that long.

Your local fire department probably recommends changing batteries twice per year, coinciding with the time change. When you set your clocks forward at the start of daylight-saving time, you change your smoke detector batteries. You change them again when you set the clocks back in the fall.

If you use lithium-ion batteries, changing twice a year is no big deal. You just throw the old batteries on the charger and use them for something else. But if you are using disposable alkaline batteries, changing twice annually could be a waste of money. You could be throwing out perfectly good batteries that have plenty of life left in them. What’s the solution? Use lithium-ion.

Not All Smoke Detectors Need Batteries

One last thing to know is that not all smoke detectors require batteries. Most of the detectors in our homes are battery-operated for simplicity’s sake. Battery power doesn’t require you to access your home’s electrical system. Having said that, it is not uncommon for new builds to offer hardwired smoke detectors.

The advantage of a hardwired detector is never having to worry about changing batteries. The disadvantage is that it will not work if the power goes out. As such, most hardware units also accommodate battery backup.

It is a safe bet that your home has at least one smoke detector. If not, you really need to change that. If your home does have smoke detectors, when was the last time you checked the batteries? Remember that a nonworking smoke detector is useless.

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