How Quickly Does An Alternator Charge A Battery?

When charging your battery, the alternator should create a voltage slightly higher than just the battery voltage, causing current to flow into the battery until it reaches the higher voltage. However, do you know How Quickly Does An Alternator Charge A Battery?

Utilizing an alternator provides the advantage of faster battery charging. It takes 30 minutes to recharge the battery on the highway, but an hour or more in the city. If your alternator is in excellent condition, you should be able to charge a flat battery to around 80% capacity in about two hours.

The most significant charge that a fully charged 12 v battery charger may get is 14.2V. The alternator controls the rate at which the battery is charged. Many people assume that the car’s battery is in charge of the vehicle’s whole electrical system.

On the other hand, the alternator is in charge of ensuring that everything works properly. Rather than that, a tiny number of us may be concerned with the question, How Quickly Does An Alternator Charge A Battery? This page will give you all the necessary information on the time of the alternator charging a battery.

Quickly Does An Alternator Charge A Battery

What Is An Alternator?

The alternator is a term that refers to a device that generates electricity. The alternator’s function is to give electricity to the vehicle and recharge the battery. Except for a few hybrids and internal combustion engines, no automobile on the road today does not have an alternator.

It is customary to locate the alternator near the front engine and surround it with a strap. The most often asked question is if a malfunctioning alternator may deteriorate the battery. Naturally, when a battery cell is faulty, it may overcharge. Thus, familiarity with the specifics of an alternator is critical.

Alternator Components

The components of an alternator are intended to provide the vehicle with the necessary power. The following are the primary components and their functions in your car’s charging system:

Rotor And Stator

The rotor and stator are drawn together by an internal magnetic field, which spins the rotor around and around in the stator’s copper wire. Electricity is generated by the movement of magnets along a wire.

Rectifying Diode

Diode rectifiers convert alternator voltage to a form compatible with battery charge.

Regulator Of Voltage

The voltage regulator is in charge of maintaining the alternator’s output voltage. It monitors the battery’s voltage and distributes power to the vehicle’s remaining components.

Cooling Fan

Cooling the heat produced by alternators is required. They also include spinning fans for additional cooling in addition to the vents and metal casing. The fan blades in earlier versions are often located on the outside.

The Alternator’s Function

While the alternator is a critical component of your car’s power system, it’s worth noting that batteries fail much more commonly than alternators. The essential function of an alternator is as follows:

Electricity Is Generated

The voltage of a car’s battery varies depending on the engine’s condition. Before learning how the alternator generates power, it’s critical to understand how many volts a vehicle battery contains (car battery voltage chart). A combustion engine causes electricity. A serpentine belt drives the alternator in most current automobiles, and the belt’s movement supplies mechanical energy to the alternator’s rotor.

As the rotor revolves, it creates power. When the rotor’s magnets pass over the stator’s copper wires, they generate a magnetic field. In a stator, this magnetic field generates and stores electricity. The voltage regulator then distributes and regulates the battery’s voltage.

Battery Charge

Before the battery can use the alternator’s output, it must change the format. It is because electricity may travel in any direction. Alternators create alternating current (AC) power, which may flow in the opposite direction of the current provided by a vehicle battery on occasion.

Before it reaches the voltage regulator and is subsequently delivered into the battery, the diode rectifier converts alternating current (AC) to direct current (DC). After conversion, the battery may utilize the converted energy to recharge itself.

Conversion Of Mechanical To Electrical Energy

The crankshaft pistons ignite the gasoline pumped into the combustion chamber from the tank. The crankshaft directs the explosive energy of combustion to an alternator through a serpentine belt. While the alternator’s pulley rotates, mechanical energy is converted to electrical energy. Having a professional tighten your alternator belt can aid in keeping your alternator functioning smoothly.

Powering Accessory

Although the alternator drives practically every electrical system component, the battery may provide some power. Electrical components in your automobile include power steering, power windows, lights, and wipers. Therefore, if you believe your alternator is damaged, use as little energy as possible until it is fixed.

How Many Volts Should A Car Battery Have When Fully Charged?

Automotive batteries that are fully charged should have a voltage of 12.6 volts or above. This reading should be between 13.7 and 14.7 volts while the engine is operating. If you do not have a multimeter, you may test your electrical system by starting the vehicle and turning on the headlights.

If they are faint, this indicates that the battery is powering the lights and that the alternator produces little or no charge. If the lights become brighter as the engine is revved, the alternator is producing some current but not enough at idle to keep the battery charged.

If the lights remain steady in brightness and do not alter in intensity while the engine is cranked, the charging system is most likely operating correctly. Whether you’ve been having battery system difficulties and the headlight test passes, you should check to see if the battery retains a charge or if anything on the vehicle is draining it.

Factors Affecting A Car Battery’s Charging Time

The time required to recharge a car battery varies considerably. The following are the relevant factors:

  • A well-maintained sulphuric acid and water battery charge more quickly than a battery with issues.
  • A 12 v battery charger will likely charge more quickly than a 24-volt battery.
  • In 4-5 minutes, a high-capacity charger can fully charge the battery. If the charging is slowed down, it might take up to 24 hours for a dead battery to be charged entirely.
  • Unlike idle, driving faster on the interstate rapidly charges the battery.
  • An alternator with greater power and fewer loads will charge a battery more quickly than one with inadequate power.


A functional alternator is crucial. Understanding How Quickly Does An Alternator Charge A Battery? And the numerous duties of an alternator can help you take better care of your vehicle and recognize any possible problems. After reading this article, you will understand precisely how long the alternator takes to charge the battery. I hope it proves beneficial to you.

Frequently Asked Questions

How Much Time Does an Alternator Need to Charge a Dead Battery?

As previously stated, various variables determine the length of time or distance required to recharge a battery. It may take up to 60 miles to completely recharge your battery, depending on your driving speed, alternator output, and battery capacity.

Can the Alternator Recharge a Dead Battery?

Rather than charging a dead battery, alternators are designed to power continually running gadgets. Using an alternator to recharge a dead battery can prematurely fail the alternator.

How long does it take for a 12-volt battery to be charged by an alternator?

Charging periods vary according to battery type and charger. In an hour of driving, it may completely recharge a 12 v battery charging voltage charged by the car’s alternator. The power of an alternator varies between 45 and 200 amps; while a 10 amp battery charger how long takes between 4 and 11 hours to charge the battery completely.

Is the Alternator Charging the Battery While the Engine Idles?

Yes, when the engine is idle, the alternator charges the battery. So long as the engine crankshaft turns the alternator mechanically. Thus, the alternator can certainly manage 80 amps while idling, and it can charge a completely discharged battery to 80% in around two hours.

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