Are Rechargeable Batteries Better Than Alkaline? Most of the Time.

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Many of my favorite things as a kid—from my Walkman to the TV remote—required AA or AAA batteries. That technology wasn’t always reliable. Sometimes I’d flip open the battery slot of a rarely used toy to find a crusty, whitish discharge from a leaky AA inside, or I’d leave the ’90s-era rechargeable batteries juicing up on a bulky charger for an entire day only to have them die after just a few hours of use.

Since then, rechargeable batteries have become less expensive, more reliable, and much longer lasting. As Isidor Buchmann, CEO and founder of the Canada-based battery technology company Cadex Electronics, explains on the company’s educational resource site Battery University, many of today’s rechargeable batteries are made of nickel–metal hydride (NiMH), a more efficient material than reusable alkaline, and are chemically sealed to prevent battery leakage from crusting up your electronics. They hold a charge for much longer than the rechargeable batteries that were available in the 1990s—or even a few years ago—and you can recharge them hundreds of times over.

In most cases, these days you’re better off using rechargeables. They’re safe and reliable, they create less environmental waste, and as we explain in the Wirecutter guide to rechargeable batteries, they pay for themselves after about six recharges, even with the added cost of a wall charger (for which Wirecutter also has a recommendation). Going by a 2012 case study for the California Department of Resources Recycling and Recovery, we can estimate that about 4 billion disposable batteries are shipped to the US each year. That means the average US household burns through about 47 batteries per year. But you could buy just 12 rechargeable batteries every four years (the lifespan of some rechargeable batteries) instead of 188 disposables. And you wouldn’t lose much performance: The best rechargeables can power your devices on a single charge for just as long as most high-quality single-use batteries can, but at a fraction of the cost over time.

However, single-use batteries are still the better option in a few instances.

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1. Low-power devices

Electronics that constantly draw low amounts of power—such as some wall clocks, headlamps, or bike lights—work better with disposable alkaline batteries. Alkaline batteries start with a slightly higher voltage that in many conditions decreases faster than that of rechargeable batteries. Whereas an alkaline battery may drop from “powering” to “dead” pretty quickly, a rechargeable battery may hang on at a lower voltage for slightly longer, resulting in unexpected behavior such as dimming lights or a clock that can’t keep time.

2. Smoke alarms

Most alarm manufacturers recommend against using rechargeable batteries to power a smoke alarm. Smoke alarms that are not hardwired into your home’s electrical system get power in a few ways: a built-in battery designed to last up to 10 years, or disposable 9-volt or AA batteries that you should replace once a year. No matter what kind of smoke alarms you have, according to the US Fire Administration, you should test the battery monthly and replace the entire device every 10 years.

“Kind of like your cell phone tells you when its battery is low, a smoke alarm should beep or chirp to tell you when it’s time to replace the battery, and it should continue to chirp for at least seven days,” said Richard Roux, senior electrical specialist for the National Fire Protection Association. “If you’re not using the recommended type of battery, the smoke alarm might stop chirping before you realize it needs to be replaced.”

If you’re not sure what type of battery the manufacturer recommends and you don’t have the instruction manual handy, said Roux, you can always look it up online using the serial number printed on the smoke alarm.

3. Emergencies or power shortages

Disposable batteries are also your best bet for emergency preparedness kits because, as Buchmann explains on the Battery University site, they have a much longer shelf life than rechargeables—up to a decade, versus a few years. Just be sure to check the expiration date on your single-use batteries so that you know roughly when to replace them.

“When you buy milk in the store, there’s a date on it, but when you buy alkaline batteries you don’t usually check the date,” Buchmann said in an interview.

Disposable batteries can also come in handy when it’s inconvenient or impossible to recharge, said Buchmann, such as on backpacking trips. He added,“The materials and chemistry of alkaline batteries are more rugged than rechargeables, so they can take more abuse.”

Regardless of which type you’re using, no battery lasts forever. To find out how to safely dispose of worn-out batteries, check the Earth911 site or your local recycling center.