The average lifespan of a car battery is three to five years, but the exact time depends on factors like temperature exposure and driving habits. Since batteries are usually located under the hood, the extreme heat during the summer months can begin to discharge the battery in under 48 hours. Heat evaporates liquids inside the battery, resulting in internal damage that shortens the lifespan.
Your driving habits also impact battery life. Stop-start driving (which shuts down your car engine at stoplights to save fuel), or frequently driving for less than 20 minutes uses battery power without giving the alternator enough time to recharge. By repeatedly draining the battery to low levels, you also shorten the lifespan.
Test your battery and electrical system twice a year to reduce your chances of failure. Use a multimeter to measure the voltage of your battery. A fully charged battery should measure at 12.6 volts or above; when the engine is running, the battery should measure somewhere between 13.7 and 14.7 volts.
If you don’t have a multimeter, you can test the electrical system of your car by starting the engine and turning on the headlights. If the headlights are dim, then the lights are running off the battery and the alternator is producing little to no charge. If the lights get brighter when you rev the engine, the alternator is producing some current, but may not be producing enough to charge the battery completely. If the lights have normal brightness and don’t change intensity as you rev the engine, your charging system is probably functioning normally.
If your car does need a new battery, check your owner’s manual for the original equipment manufacturer’s recommendations to select the right battery for your vehicle. When removing your old battery, remove your battery hold-down clamp and disconnect the negative (black) cable first, then the positive (red) cable. Use the heavy duty strap to carefully lift out the old battery. Once you’ve removed the battery, check the battery tray and clean it or replace it if it’s heavily corroded. Lift the new battery into place, and secure the battery with the hold-down clamp. Spray terminal ends with an anti-corrosion solution, and connect the positive (red) cable first, then the negative (black) cable. Be sure to wear eye protection and rubber gloves when working on batteries, and recycle your old battery at any local battery retailer.
A little at-home maintenance can keep your battery working at peak performance. First, use a post cleaner to clean corrosion from the top of the battery and from around the battery cables. Scrub your car battery terminals clean using a nonmetallic brush and a baking soda cleaning solution (one tablespoon of baking soda dissolved into a cup of water). Once clean, flush with cool water and dry with a towel. Next, check the level of electrolyte in the battery—if the battery needs water, add clean distilled water, and be careful not to overfill the cells. If you find any cracks in the battery case, it’s time to replace the battery.