Hobbies Cars & Motorcycles Dash Lights: The Battery Light on Your Dashboard Share PINTEREST Email Print Matsou / Getty Images Cars & Motorcycles Cars How Tos Buying & Selling Basics Reviews Tools & Products Classic Cars Exotic Cars Corvettes Mustangs Tires & Wheels Motorcycles Used Cars SUVs Trucks ATVs & Off Road Public Transportation By Matthew Wright Matthew Wright has been a freelance writer and editor for over 10 years and an automotive repair professional for three decades specializing in European vintage vehicles. our editorial process Matthew Wright Updated September 30, 2018 If you take a look at your dash when you turn the ignition key—but before you actually start the car—you'll likely see that one of the lights looks like a little battery with a "+" and "-" sign on it. This is your battery or charging light. Once you start the car, all your dash lights should go off. But what should you do if the battery light starts flashing while you're driving? Purpose of the Battery Light Your car or truck is equipped with a large number of safety monitoring systems that are constantly checking to see what's going on inside the engine, with your brakes, and even inside your tires, as is the case with a Tire Pressure Management System (TPMS). Not only is the information stored inside your car's electronic control unit (ECU), which is the main computer, or brain, in your vehicle, there is often a light or series of lights on the dashboard that come on when an error has been discovered in a certain system, like the braking system or the charging system, for example. This system is tremendously helpful to drivers. If you see a warning light come on, you know that your car likely needs some kind of immediate attention, even if nothing appears to be malfunctioning fully yet. When the Battery Light Comes On This light comes on when your alternator is not making electricity and the car is running off of battery power alone. You can drive a short distance on the battery, especially if you turn off most of your car's electrical items (like the radio, air conditioning, etc.), but there's no way to know how far you'll get before it dies. So the best thing to do is to pull over as soon as it's safe. Unfortunately, while this little light is really good at getting your attention, it's really bad at telling you exactly what the problem is. That's why when you see a light like the battery light come on, you have to do a little research or have some knowledge to work with before you can decide if you should stop on the side of the road and call for a tow, keep on truckin' to your service station, or drive home and fix the problem yourself. Some Preliminary Checks If you have some automotive maintenance experience and you aren't too far from home, you might want to drive your car to your garage and run it through a charging system check. Usually, the check battery light indicates that you either need to replace your alternator belt or the alternator. But not so fast! Before you do this, go ahead and check your battery connections. The light can come on even if your alternator belt is intact and your alternator is charging well, but your battery connections are keeping the electrical circuit from properly electrifying the car's systems. Even a bad ground wire can be enough to cause a poor charging situation and trigger the battery light. Sometimes, cleaning the battery connections will fix the charging problem without costing you a penny, or at least not much more than a penny. Remember to always look into the least expensive repair option before you dive in for the big-ticket fixes. In the case of cleaning your battery terminals, an ounce of prevention really is worth a pound of cure.