What should the car battery voltage be while driving?

Do you feel your car’s battery is losing power while driving? First, What should battery voltage be while driving?

While you are driving, the battery charge should range between 13.7 volts to 14.7 volts, and this marks the full charge.

But of course, it’s easy to note that your battery is losing power while driving. For instance, if it was night, the headlight would appear dim. Other parts that get power supply from the battery may also start functioning abnormally.

The car’s battery voltage drop may suggest that the battery is weakening or something is affecting the ability to retain voltage or recharge while driving. Once the car battery voltage drops, it may not be able to start the car upon stopping the engine.

If you have such signs of voltage drop with your car’s battery while driving, you need to reach your mechanic for a battery checkup.

What causes a voltage drop for the car battery while driving?

When the battery voltage drops, you may easily read it through the battery gauge while driving. There can be several reasons why the voltage drops; these may include a bad alternator, battery corrosion, loose connections, and the battery is old.

a.A bad Alternator

The alternator in the car is responsible for the generation of electricity. This is an important part that provides power to the electronic systems, including the battery in the car.

The alternator takes the mechanical power produced by the engine; then, it converts it into electrical energy, a power that enables the recharging of the battery.

Therefore, if the alternator has developed some fault or has gone bad, it won’t be able to recharge the battery. When the car’s engine is running or when you are driving, the battery should be undergoing recharging.

If the alternator is not providing electricity, the charge in the battery will probably get used up, and voltage drops.

However, the alternator can be good and ready to recharge the battery but its components, such as the serpentine belt. The serpentine belt or alternator belt rotates the alternator system’s electrical conversion. If such a belt is cut off or too old, it won’t enable spinning.

b.Loose connection

As you drive your car over different terrain, the components in the car will experience vibrations, especially on rough roads. This means if there are some loose parts in the car, they will keep loosening and maybe apart. In such a case, the car battery needs to be tightly connected to the terminals for the effectiveness of electricity flow.

If the battery is loosely connected, there will be disconnections at better terminals when the vibration is too high when the car moves over rough surfaces. In such a situation, the electricity from the alternator won’t flow in for recharging.

Therefore, having a bad car battery grounding will lead to poor charging, and the voltage will keep dropping as you drive.

c.Corrosion around the battery

Corrosion on car batteries is not something rare, especially if the battery is not well inspected from time to time. Most parts that experience corrosion is terminals that receive charges from the alternator. If such issues are with your battery, the alternator won’t be recharging the battery effectively, and this is why you may see battery voltage dropping as you drive.

d.Old car Battery

Does your car’s battery voltage keep dropping as you drive? How old is your battery? When did you replace it?

When you buy a car, every part will not keep its original status; there will be wear and tear as you continue using it. The same way your car’s battery. Therefore, your car’s battery will get older over time.

The car’s battery’s ability to hold charge will be proportional to aging. Therefore, if you have not replaced your battery or it is old, think of an old battery once you see signs of voltage dropping as you drive.

Should battery voltage go down while driving?

The battery voltage should not go down while driving under if its components for recharging are working normally. However, if the alternator is bad, and there is a loose connection, corrosion on the terminals, or the battery is too old, there should be expectations of voltage drop while driving the car.

What should a car battery voltage be with the car running at idle?

When the car’s engine is running at idle, there will be the generation of electricity that will recharge the battery. Therefore, the battery voltage will range between 13.7 volts and 14.5volts.

What voltage is too low for a car battery?

If the voltage of the car battery ranges between 11.75 volts and 11.89 volts, whether the car is running or idling, it is too low to continue operating the car’s systems. Indeed, a battery with such a range of voltage is considered dead, and replacement is needed.


Having a healthy car battery enhances performance and, indeed, driving experiences. A good battery should read around 13.7 volts and 14.5volts on a multimeter.

If such voltage is dropping as you drive the car, you need to check up on the alternator, battery grounding, or corrosion. Old batteries will also affect the chances of retaining a charge. If such issues are affecting the voltage retaining while driving the car, you need to replace them.

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