Many of my favorite things as a child — like my Walkman, for example — required AA or AAA batteries. Batteries back then weren’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, chief executive and founder of Cadex Electronics a battery technology company based in Canada, explains on Battery University, the company’s educational resource site, 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.
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In most cases, today you’re better off using rechargeable batteries over disposable ones. 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 we also have 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 average life span of some popular rechargeable batteries) instead of the 188 disposables you would otherwise need. 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:
Electronics that constantly draw low amounts of power — such as some wall clocks, headlamps, or bike lights — work better with disposable alkaline batteries. Alkalines release power consistently right up until they die, whereas a rechargeable battery’s voltage gets gradually lower and lower over time, slowing down the device or cutting off power prematurely.
Most alarm manufacturers recommend against using rechargeable batteries to power a smoke alarm. Smoke alarms that are not hard-wired into your home’s electrical system get power in one of two ways: a built-in battery designed to last up to 10 years, or a disposable 9-volt battery 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 when your cellphone 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, a 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.
Disposable batteries are also your best bet for emergency preparedness kits because, as Mr. Buchmann explains on 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,” Mr. Buchmann said in an interview.
Disposable batteries can also come in handy when it’s inconvenient or impossible to recharge, said Mr. Buchmann, such as on backpacking or camping 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 of all types, check Earth911, or your local recycling center.
A version of this article appears at Wirecutter.com.