9 Causes of a Car Battery Light On While Driving
The battery warning light while driving is a cause for concern as it most likely means that your charging system is malfunctioning. Ignoring this warning signal could leave you stranded with a dead battery. Learn the most common reasons why your battery light comes on and what to do if it comes on while driving.
How a Traditional Vehicle Battery Works
Supercharging occurs when the crankshaft pulley spins the alternator belt (also called a serpentine belt or power take-off belt), which spins a rotor (sometimes called a generator) inside the alternator.
The alternator receives kinetic energy from a spinning disk and converts some of that energy into alternating current and then into direct current for storage in the battery. This energy is used to power headlights, power windows, heated seats, radio, air conditioning, DVD player, cell phone chargers, and more.
The voltage regulator maintains the necessary voltage while the battery is charging. It is often a component of the engine control unit (ECU). Electric current (consisting of electrons) flows from one terminal of the battery, through the accessories, to the other terminal of the battery. Various wires called ground straps in the engine compartment connect parts of the wiring harness to the chassis and help complete various circuits.
Main reasons for the battery light coming on
Every time the vehicle is started, the battery warning light comes on briefly and turns off after a few seconds. This is a system test that indicates that the battery light on the dashboard and all monitored components of the charging system are functioning as expected.
If you experience this problem, there are many possible causes that you should check when troubleshooting.
Safety is important when working with electrical systems, so check your user manual for general tips. We recommend wearing gloves or safety glasses to protect your eyes from battery acid splashes and rubber gloves to protect yourself from electric shock. Disconnect the battery before cleaning it or inspecting it closely.
If you are having trouble charging your battery, you will notice other symptoms such as dim headlights, a slow clock, and a non-functioning air conditioner or radio.
1) Bad Battery
A typical 12-volt battery has a lifespan of 3-5 years. Although some manufacturers advertise a longer lifespan, you shouldn’t expect your battery to last that long.
These traditional batteries have lead dioxide plates in each of the six cells, and lead plates that are submerged in a sulfuric acid electrolyte solution. As the battery ages, the cells or plates can break and cause the electrolyte to leak out of the battery. If this happens, the battery should be replaced. Poor wiring or grounding can prevent your battery from receiving or holding a charge.
2) Bad Generator
It’s relatively easy to check the functionality of your generator with a multimeter. The voltage should be between 13.6 and 14.6 volts. If the voltage is less than 12 volts, the battery light will come on and the generator may need to be replaced.
The voltage regulator is the component that limits the power to a safe limit of 14.5 volts and may be the culprit if it’s not working as intended.
3) Faulty alternator belt
The alternator belt is very important as it connects the alternator, engine and ancillary equipment. Over time, the belt can crack or break completely. It can also be misaligned, too tight or too loose.
If a faulty alternator belt is the cause of the battery warning light, you may also hear a squeaking noise coming from the hood while the vehicle is running.
4) Corrosion on the battery terminals
The positive and negative terminals of the battery are the flow path for electrical current. Therefore, it is important not to increase resistance by covering them with other materials that are less conductive. Corroded electrical components are poor conductors. This is often the cause of poor connections even in healthy systems.
It is an acidic substance that attacks car paint and irritates the skin. So be careful. Common rust has a reddish color and can also affect the conductivity of electrical components. If you notice corrosion on your battery terminals, wear the appropriate protective gear and clean the terminals using a stiff bristle brush and a solution of 1 tablespoon baking soda in 1 cup water. This solution is alkaline, so it will neutralize the acid that is corroding them.
They are inexpensive and make the job a little easier.
5) Loose Battery Cables
To ensure a good connection, the battery cable needs to fit snugly around the battery terminal. You can’t just twist the cable end around the battery post by hand.
If you have trouble with the connection, make sure it’s tight by tightening it with a wrench or pliers. The battery screws can come loose if you tighten them too much, so don’t overdo it.
6) Faulty Battery Cables
Battery cables carry power from the battery to the vehicle itself. In other words, these cables are small but mighty.
7) Bad Ground Strap
A ground strap, or ground wire, completes the circuits of different components around the vehicle so electricity can flow as it should.
More than likely, you will notice a specific subset of components in a localized area start to act up if a ground strap is loose or corroded.
8) Faulty Wiring
There are a lot of wires involved in the electric charging system so if any of these are broken or disconnected then the battery warning light may come on. Wires typically break around the connectors rather than further up the wiring harness. The wires and connectors may become stiff and brittle with age.
9) Too Many Accessories in Use
Since the vehicle’s accessories run off of the alternator belt, which is also how the battery is charged, using them in excess can siphon too much electricity, leaving the battery “hungry”.
This can sometimes occur with an aftermarket sound system that uses an amplifier that consumes more power than the alternator can handle. Usually this is the case when adding a large, power-hungry subwoofer.
What To Do If the Battery Warning Light is On
If you are driving and the battery warning light comes on, know that you probably don’t have much time left of driving before your vehicle dies. Try to get home or to a mechanic as soon as possible.
Whatever you do, don’t turn off the engine until you’ve reached your destination! The starter motor takes a lot of electricity and if there isn’t enough charge in the battery then the vehicle won’t start. Keep an eye on your temperature gauge, as overheating can be an associated issue with charging problems.