What devices do you need batteries for? Just about any battery can power a low-drain device like a remote control or a flashlight. However, for high-drain devices like cameras, battery life varies widely, depending on type. Lithium batteries generally last the longest in high-drain devices, but rechargeable ones can provide better long-term value, especially in devices that see a lot of use. If you're choosing rechargeable batteries for a high-drain device, look for a high capacity, as measured in milliampere-hours (mAh). The higher the mAh rating, the longer it will run on a single charge. However, high-capacity batteries also cost more and don't have as long a service life, so they're not worth using for low-drain devices.
How will you store your batteries? Heat and humidity can shorten a battery's shelf life. However, according to experts, it's a myth that batteries should be refrigerated to prolong their life. This was true for old carbon-zinc batteries, but for today's alkaline batteries, any reasonably cool and dry place will do. Some experts recommend against keeping loose batteries in a pocket or purse where they can clash against other metal objects, such as paper clips or coins. This could short-circuit the batteries, resulting in overheating or leakage.
Do you plan to recycle the batteries when they die? If so, rechargeable batteries are your best choice. There are more than 30,000 locations in the U.S. and Canada that will take rechargeable batteries for recycling, including large chain stores such as Sears, Target, Walmart and Home Depot. (You can find a site near you at Call2Recycle.org.) Drop-off recycling for disposable batteries, by contrast, is hard to find in most areas. The exception is Vermont, which has over 100 drop-off locations in retail stores, libraries, and other public areas. Other states have a few drop-off locations, but often you have to recycle this kind of battery by mail at your own cost.
If you're investing $10 or more in a set of rechargeable batteries, you'll want them to last as long as possible. Experts recommend using a "smart" charger to prolong battery life. Smart chargers, which are available for as little as $10, can sense when a battery is fully charged and shut themselves off automatically. Less expensive chargers, by contrast, simply run for a fixed length of time. Batteries may end up undercharged, giving you less than full power, or overcharged, shortening their life. Any charger that is a smart charger will say so on the label. Testers at TheWirecutter.com particularly like the Panasonic Advanced Charger BQ-CC17 (Est. $17), which comes bundled with four AA Eneloop Rechargeable batteries.
When alkaline batteries get old, they can develop leaks. The fluid inside them, potassium hydroxide, is harmful to eyes and skin. As it dries, it reacts with carbon dioxide to form potassium carbonate, a white powder that's much more stable, but can still damage your devices. Here are some tips to prevent leaks and deal with them if they occur: