Best car batteries

Getting stuck with a dead battery is an annoyance at best. If you're stranded in bad weather or an isolated location, it can jeopardize your safety. So, with winter around the bend, now is the time to check up on the health of your battery and replace it if necessary. (See our complete car battery advice.)

When shopping, don't assume that buying a well-known brand or spending top dollar is the way to go. Four different brands grabbed the top spot in the six group sizes we tested. That means a battery that topped one category may be an also-ran in the size you need.

DieHard batteries, for example, scored at or near the top in some of the group sizes we tested but ended up dead last in others. And with prices ranging from $110 to as much as $175, DieHard models were some of the most expensive.

On the other hand, relatively affordable EverStart batteries from Walmart were some of the top scorers in all six group sizes we tested. They're also among the most reasonably priced, ranging from around $85 to $110.

Absorbed glass mat (AGM) designs are strong performers, accounting for the top three models in Group 34. But they are also the most expensive, with the $210 Optima at the top of the range. AGM batteries are being used in more new cars to supply added power for electronic safety and convenience features, as well as fuel-saving engine stop-start systems. But our tests have found similar or better overall performance from batteries costing less than half as much.

Although cold temperatures can make a battery struggle to start a car, a battery actually degrades more quickly in hot weather, and one that has weakened over the summer may fail completely when the mercury drops. Moreover, because of the efficiency of modern electrical systems, most cars can now start with a minimum of cranking. So, you may not even know your battery is getting weak until it's too late.

The key to avoiding battery failure is regular testing. Have the battery tested annually by a mechanic once it is 2 years old if you live in a warm climate, or once every four years in colder climes. If your battery fails the test, don't hesitate to replace it, even if your car is still starting right up.

Batteries come in a variety of sizes. You'll find the right one for your car in the owner's manual or an in-store fit guide. Armed with that information, you can check our Ratings to find the best model for your needs and budget. Then, narrow your choices based on these three important criteria we evaluate in testing.

Life. Batteries that scored well in our life test are the models that held up longest through repeated cycles of draining and recharging while immersed in water heated to 167° F. This simulates the typical conditions a battery is exposed to under the hood of your car.

Reserve capacity. This is an estimate of how long a battery can power your car if the electrical system fails. It's also important if you do a lot of stop-and-go driving with frequent restarts.

Cold-cranking amps (CCA). Focus on CCA if you live in a cold climate. A high score here indicates good starting performance in sub-freezing temperatures.

Keep in mind that any battery will lose strength over time, even sitting on a store shelf. Get one that's six months old or less. Look for a code printed on stickers on the case that uses a letter for the month (A for January and so forth, although September skips I and goes to J) and a number for the year (3 for 13).