How to maximize the life of your car's battery

Car starter batteries—the 12-volt batteries used to start the engine and power accessories in most cars—typically last 3 to 5 years but can tap out much sooner if you don’t take proper care of them.

These simple steps can help your battery live a long‚ healthy life and keep you from needing battery service early.

2. Set your dome lights to "door" (& leave them there)

Another common culprit in dead batteries is interior dome or reading lights. While they draw less power than headlights, they're easier to accidentally leave on. Given enough time, they'll run the battery empty too.

Usually that happens when manually switching the lights from "door" to "on" to read or find something in the car and forgetting to switch it back. If you need the reading lights and you're somewhere safe like a garage, it's better to leave the lights on "door" and activate them by opening a door. All you need to remember is to close the door when you're done.

3. Unplug accessories when they're not in use

Many cars have an "accessory" ignition setting that powers the radio, lights, 12V accessory sockets, and USB ports with the battery instead of the engine. Using this less (or not at all) will keep your battery healthier, as will having fewer accessories plugged in if you do use it.

Increasingly, new cars are also offering "always on" accessory ports that provide power from the battery even when the ignition is completely off. These may remain on at all times, or they may keep the port active for a few minutes after turning off the car. Make sure you know whether your car has one or more of these, and if so, make sure not to leave phone chargers, dash cams, or other accessories plugged into them when you're not using them. 

4. Drive your car at least once a week

Even if you don't have any always-on accessory ports draining power, your car's battery will slowly run down if it's not started. Your car should ideally be started and driven for 30 minutes or more at least once every week. (Starting the car but not driving it doesn't help the battery, which needs time to recharge from the engine.) 

Not only will this keep your battery charged, it will also keep cold start combustion contaminants from collecting in your engine oil, help keep seals properly lubricated, and more.

Out of town for a while? See if friends or family can take your car for a weekly 30-minute drive.

5. Avoid exclusively taking short trips

Taking several short trips is harder on your battery than taking a single long one, because it uses stored energy to repeatedly start the engine but doesn't get enough time to fully recharge. This can also lead contaminants to build up in your engine oil.

Under most circumstances, taking a lot of short trips (shorter than a few miles or 15 minutes of driving) is fine for modern cars as long as there's at least 1 longer trip (more than 30 minutes) each week. The shorter the trips are and the more electric accessories you use, the more important it is to mix in longer drives.

6. Protect your battery from extreme hot and cold

Very high and very low temperatures are bad for batteries. Leaving your car to bake in the summer sun or freeze outside in winter takes a toll on your battery's chemistry and shortens its life. Parking your car in the garage if you have one (especially if it's climate-controlled) limits your battery's exposure to the elements and extends its life.