Why Is Your Battery Light On and What Does It Mean?

When you turn the car on, its dashboard briefly lights up like an overcrowded fast-food menu. An array of illuminated numbers, letters, indicators, read-outs, and symbols flash and quickly fade to black. If there’s an issue with the vehicle’s charging system, however, the little battery light will remain on with the intense glare of a kangaroo mob.

Although a battery-shaped light suggests a battery problem, reality is more complicated. The issue could simply trace to the battery or its terminals, but it could also be the result of a failing alternator, a bad connection, or a number of other issues.

Regardless of the problem, a bad charging system will drain the battery and cost you money, so you’ll want to address it immediately. To figure out the cause of your battery light’s unexpected appearance, The Drive’s die-hard informational team has laid out a guide to identifying, diagnosing, and solving your car’s problems. 

Yippee ki yay, let’s get into it!

The dashboard light shaped like a rectangular Lego-looking battery is officially known as the Charging System Light, and this refers to traditional combustion vehicles, not electric vehicle charging. If the light stays on after turning the vehicle on or lights up while driving the vehicle, it’s a warning to the driver that the charging system is not running efficiently enough to properly charge the battery while maintaining power to necessary accessories.

If you notice your charging system light on your dashboard, immediately drive home, to a local dealership or garage, or a local auto parts store using only backroads, not the highway.

A modern vehicle’s charging system, which functions to keep the battery charged, includes a battery, wiring, an alternator, and the electronic control unit (ECU). Older vehicles also had a voltage regulator.

Alternator: The alternator accepts mechanical energy from the engine and turns it into electrical energy to power accessories and charge the battery.

Battery: The battery provides energy to start the vehicle and to power its electronics.

ECU: The electronic control unit, not to be confused with the engine control unit, is a device that manages the linked electronic system. It regulates where, when, and how power is held or flowing.

There are a multitude of reasons why the charging system is not operating at maximum capacity. Let’s go over what they could be.

Check all connectors for corrosion and proper seating. Retighten, if necessary.

The serpentine belt is the piece of reinforced rubber that turns the alternator’s pulley and powers the alternator. If the belt isn’t properly running the alternator, it could create charging issues.

Check the battery terminals to make sure the cables are correctly connected. If a wire is disconnected, clean the terminals, reattach the cable to the battery, and tighten.

Check the battery terminals for corrosion that could be creating an inconsistent connection. Visit The Drive’s guide for How To Clean Battery Terminals for more.

Use a multimeter to test the battery for the correct voltage. A fully charged battery should register 12.6 volts or more. If it’s off, try recharging the battery with a trickle charger before replacing it. Visit The Drive’s guide for How To Change a Car Battery for more.

Use a multimeter to test the alternator. It should read between 13.8-14.2 volts. If the voltage is below normal, the alternator might need to be replaced.

Although a charging system light is the easiest way to notice something is wrong, there might be accompanying symptoms that could tip the problem prior to the light’s illumination or provide more information as to why the light turned on in the first place. These symptoms, which are unfortunately similar across all three parts, could indicate the bigger issue:

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It means there’s an issue with the vehicle’s charging system, which includes the battery, the alternator, the wires, and the ECU.

If something in the vehicle’s charge system isn’t functioning properly, there is risk of the car shutting off without warning. It’s also possible that if the vehicle dies, it might not be possible to start it back up. Because of this, we do not recommend or suggest driving with the battery light on to any place other than back to your house or a service center. If the light comes on before driving, we do not recommend driving.

Slowly drive your car home, to a service center, or to an auto parts store. Then, diagnose and fix.

Use a multimeter to check the voltage on both the battery and alternator to verify they’re functioning at the correct levels.

It is possible for a car to start with a bad alternator, but it will likely immediately die.

Ancel Classic Enhanced Universal OBD II Scanner

Equus Auto-Ranging Digital Multimeter

Fastronix Military Spec Battery Terminal Top Post Kit

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