What size battery do you need? Batteries come in various sizes called "Groups." You can find what size to buy by checking out your current battery or by looking it up in your car owner's manual. Most stores can also let you know the size you need using your car's make and model, but we've seen lots of reports that online tools that do that are not always accurate.
Do you live in a hot or cold climate? Choose your car battery accordingly. Hot-weather batteries, often labeled "South" or "S," are designed to endure extreme heat. Cold-weather batteries sometimes labeled "North" or "N" have higher cold-cranking amps (CCA).
Do you need a high-performance battery? Probably not, experts say, if you drive an ordinary car. But if you have loaded your car with power-hungry goodies such as power amps, extra lights, winches and more -- or if you like to run your accessories with the engine off -- you might want to spend extra for a high-performance battery like the Optima YellowTop D34/78 (Est. $200). It pours out plenty of power and shrugs off repeated drain-and-recharge cycles.
Do you drive off-road? Consider the Optima brand. Instead of fragile plates inside, Optima batteries have sturdy coils that stand up better to constant vibration. Also, Optima batteries have a completely sealed case, so they're less likely to leak when jostled around than a battery with caps.
Do you want it installed? Garages, most auto-parts chains and some other stores including Walmart will install your battery for free if you buy it there. Sears charges extra for installation (Est. $10), and Costco doesn't install batteries at all. Some online retailers, including Amazon.com, can arrange for local installation of batteries bought on line.
Choose a fresh battery. Like all batteries, car batteries lose strength as they sit on the shelf. Look on the case for a date, and make sure the battery is no more than six months old. Sometimes the date is written as a code: a letter representing the month (such as "A" for January) and a number for the year (such as "5" for 2015), ConsumerReports.org says.
Bring your old battery. When you buy a new car battery, the store will take your old one for recycling. In fact, in many states, you'll have to pay a $5 to $20 fee -- known as a "core charge" -- if you don't bring an old battery to recycle when you buy your new one (or within a specified time after the sale). States mandate the core charge to encourage recycling, which keeps the batteries' dangerous lead and acids out of landfills. It works: Car batteries are the most recycled items in the world, according to the U.S. Environmental Protection Agency., with a recovery rate of 99 percent.