Car Batteries Do More Than Power Your Vehicle

AAA Automotive Team

After a long day at work, you’re ready to head home, kick off your shoes, and binge Netflix. As you turn the key, you hear the dreaded click, click, click of your engine. It’s after 6:00 p.m., and you’re not going anywhere. Fortunately, you remember to call 1-800-AAA-HELP for car battery service. As your phone drops below 10 percent, there’s no posting your woeful story to Instagram or passing the time with TikTok videos. Without a functioning car battery, you must salvage what little phone power you have left, because charging it is out of the question.

Don’t take the small black box under the hood for granted: without it, your day grinds to a halt…literally. Modern car batteries are responsible for much more than starting your car. If your battery fails, get ready to sit in radio silence as you say goodbye to phone chargers and power seats. And this may be the only time you wish you still had manual windows.

What is a Fully Charged Battery?

While you may think that 12V constitutes a fully charged battery, 12.65V is actually considered 100%. When you’re operating at 12V, you’re only running on about 40% of power. At around 11V, your battery is almost completely discharged.

When Your Battery Begins to Fail, What Happens?

When your battery drops between 10V to 11V, vehicle accessories like the headlights, radio, and AC blower will begin to diminish in power. You’ll likely notice that the interior lights in your glove box, trunk, or door may appear dim or not work at all. Power windows will begin to crank slowly. Your engine may begin to sputter and dash lights will flicker like a Christmas tree. It takes much less electrical current to power things like your car’s air conditioner and radio than it does to crank your engine, so you may be able to use these accessories for a short period of time, even if the car won’t start.

Aftermarket accessories, such as a phone charger that fits into a cigarette adaptor, can also deplete your battery power. You may notice in older vehicles that these accessories still charge your phone or other accessories when the car is turned off, thereby creating a parasitic drain on the battery. However, many modern vehicles have safeguards in place to help prevent a dead battery and will not charge your devices if the vehicle is not running.

Modern features such as keyless entry and telematics that connect your phone to your vehicle via Bluetooth consistently draw small amounts of power, even when the car is not in use. While not a problem by itself, these features could accelerate the demise of a battery that’s already in decline. Even if your car is securely stored in a garage, do not leave the key in the car or hanging nearby, as it can continue to draw power.

AAA Mobile Battery Service

Now that you know all the different features run by your car battery, you can be on alert if they begin to diminish in power. If you do find yourself with a vehicle that won’t start, the professionals are here to help. Simply call 1-800-AAA-HELP or visit and a Technician will come to you to test and replace your battery, if needed.