Understanding your car battery is key to your vehicle's longevity and overall performance. What's most important is knowing when to get your battery replaced. That knowledge could very well be the difference between a non-eventful trip from Point A to B, and a key-turning struggle in the parking lot. The best way to know for sure if it's time to replace your vehicle's battery is to get it tested. The good news is that you can always bring any battery—auto, marine, or specialty— to your local O'Reilly Auto Parts and have it tested for free.
Most car batteries last about 3-4 years. Nearly twenty percent of all batteries tested need to be replaced. This means that over a quarter of all batteries on the road are on their last legs. Batteries operating in warmer climates have an even shorter lifespan (2-3 years). Always remember: “Summer Drains, Winter Kills.” It is highly imperative that you have a regular inspection and maintenance on your vehicle's battery, especially in hot weather. Most people might assume that cold weather puts the most stress on your battery. However, more often than not, the cold weather only finishes the job that warmer weather started. Heat is what causes the fluids in the battery to evaporate.
Another thing to keep in mind is the condition of the battery itself. From time to time, check the exterior of the battery for corrosion or other gunky build-up that can decrease your battery's lifespan. If there is significant grime or debris around your battery terminals, then it may be time for a replacement.
In the interest of your own safety, if you do plan on checking, cleaning, or replacing your vehicle's battery on your own, please make sure to wait until your car is cool. The most preferable way to do it is to let your vehicle sit overnight before performing any sort of maintenance on the battery. Also, be smart about short trips. While they aren't completely avoidable, short trips that involve frequently starting and stopping your car puts added stress on your vehicle's battery.
When it's time to choose a replacement battery, you want to make sure that you select one that has reliable starting and reserve power, and is resistant to both extremely high and low temperatures. You also want a battery that can withstand the high electrical demands of your car accessories, such as your phone chargers and GPS devices.