What is the correct charging voltage for a car?

The correct charging voltage for a car is typically between 12.6 and 14.2 volts. This range ensures that the car's battery is charged properly and the electrical system is functioning as intended.

Understanding Car Charging Voltage

The charging voltage in a car is responsible for keeping the battery charged and powering the various electrical components of the vehicle. The optimal charging voltage range is crucial for the health and longevity of the car's battery, as well as the proper operation of the electrical system.

Factors Affecting Charging Voltage

Several factors can influence the correct charging voltage for a car, including:

• Battery type: Different battery types, such as lead-acid or lithium-ion, have varying voltage requirements.


• Alternator output: The alternator, which charges the battery while the engine is running, must provide the appropriate voltage to keep the battery charged.


• Electrical load: The amount of electrical components and accessories being used in the car can affect the charging voltage.


• Temperature: Extreme temperatures, both hot and cold, can impact the battery's voltage and the alternator's output.

It's important to ensure that the charging voltage remains within the recommended range to prevent damage to the battery or other electrical components.

Checking and Adjusting Charging Voltage

To check the charging voltage in a car, you can use a multimeter or voltmeter. Simply connect the multimeter to the battery terminals or the appropriate electrical points in the vehicle. The reading should fall within the 12.6 to 14.2 volt range.

If the charging voltage is outside of this range, it may be necessary to have the alternator or other electrical components checked and adjusted by a qualified mechanic. Proper maintenance and monitoring of the charging system can help ensure the longevity and reliable performance of a car's electrical system.

How many volts should your car be charging at?

When we take a closer look, we see car battery voltage can range anywhere from 12.6 to 14.4. With the engine off, the fully charged car battery voltage will measure 12.6 volts. This is known as “resting voltage.” When the engine is running, battery voltage will typically rise to 13.5 to 14.5 volts.

What is the 80 20 rule for charging batteries?

The 80/20 rule for lithium batteries recommends: Charge up to 80% for daily use. Charge to 100% only when needed, such as before a long trip or a full discharge cycle. Avoid letting the battery discharge lower than 20%.

What should a 12 volt battery charger read when fully charged?

A 12-volt battery charger should read around 12.612.612.6 to 12.812.812.8 volts when the battery is fully charged and disconnected from the charger. During the charging process, a smart charger may display a higher voltage, such as 14.014.014.0 to 14.814.814.8 volts, as it applies a charge, but the final voltage of a resting, fully charged battery will be in the 12.612.612.6 to 12.812.812.8 volt range.
 
This video explains how to read a manual battery charger to determine the state of charge: 58sJACK of all TRADES DreYouTube · Oct 4, 2021
Voltage during charging

• Smart chargers: These chargers will typically show a higher voltage, between 14.014.014.0 and 14.814.814.8 volts, while actively charging the battery to its maximum capacity. 
• Manual chargers: These may show the voltage as high as 14.814.814.8 volts when in the "bulk" or "powering" stage, but the voltage should be lower when the battery is fully charged. 
• Constant voltage chargers: These chargers will show a voltage of 12.612.612.6 volts (or slightly higher) once the battery is fully charged and the current has stopped. However, it's important to check the voltage after the battery has had a chance to rest, as "surface charge" can make it seem like it's fully charged when it's not. 

Voltage after charging

• A fully charged 12-volt battery should read approximately 12.612.612.6 to 12.812.812.8 volts after it has been disconnected and has rested for a few hours. 
• If the reading is below 12.612.612.6 volts, the battery is not fully charged and needs more time on the charger. 

You can watch this video to learn how to check a car battery's voltage with a multimeter: 52sHSZ GarageYouTube · Aug 22, 2022

Is 14.7 volts too high on a battery?

A 14.7-volt reading is generally not too high for a 12-volt lead-acid battery while it's being charged, as it's within the typical range for a healthy alternator or charger, though it is at the upper end. However, if the voltage stays at or above 14.7 volts for a prolonged period after the battery is fully charged, or if readings are consistently above 15 volts, it could indicate overcharging and lead to damage. 
This video explains the ideal voltage range for a car battery: 1mOBD InsightsYouTube · Feb 13, 2025
What to know about 14.7-volt readings

• While running: A reading of 14.7 volts is common and usually indicates the charging system is working correctly to keep the battery full while the engine is on. 
• Maximum limit: Voltages above 15 volts are a strong indicator of overcharging. 
• Monitor the voltage: If you see 14.7 volts, monitor the charging process to ensure the voltage drops to a lower, maintenance level once the battery is full. 
• Potential for damage: Prolonged overcharging can cause the battery to lose water and shorten its lifespan. 

This video demonstrates what a charging voltage too high can look like: 56s1A Auto: Repair Tips & Secrets Only Mechanics KnowYouTube · May 11, 2020
When to be concerned

• If you consistently see a reading above 15 volts. 
• If the voltage remains at 14.7 volts for a long time, even after the car has been running for a while. 
• If you notice other symptoms of overcharging, such as a glowing check engine light or a rotten egg smell. 

If you are concerned about your battery's voltage, it is best to have a professional check the charging system for you.