# How many volts is a car battery? What you need to know

by

The battery powers your car’s engine and does a lot more. Without it, you wouldn’t be able to lock the doors, raise and lower the windows, or continue playing music. As a result, it makes sense to be curious about how something works when it has such a significant impact on your life while driving. So, the question is, how many volts is a car battery? Well, read on!

It’s annoying to deal with a dead battery, which is why regular battery maintenance is crucial because it keeps your battery in good shape. You might wonder, for instance, how many volts a car battery needs to start. To be sure your car battery won’t let you down, you need to learn this crucial number.

• How many volts is a car battery?
• How often should you test your car battery voltage?
• What are the signs and symptoms of battery troubles?
• How do you test car battery voltage?

Ok then, let’s dive in!

Contents

## How many volts is a car battery?

Typically, when discussing automotive battery voltage, we’re referring to a 12-volt battery. When we look more closely, we can observe that the voltage of a car battery can vary from 12.6 to 14.4. The voltage of a fully charged car battery will be 12.6 volts with the engine off. The term “resting voltage” refers to this. In addition, the battery voltage will normally increase to 13.5 to 14.5 volts when the engine is running. The alternator raises the battery to these greater voltages. Let’s take a step back and examine the crucial function the average 12-volt battery performs in your car’s starting and charging system in order to better understand.

• Electrical energy is stored in the battery.
• To start the engine, the starter transforms electrical energy into mechanical energy.
• Once the engine is running, the alternator produces electrical power to replenish the battery energy used by the starter.

The alternator recharges the battery to provide extra current, the electrical energy is once more transformed into mechanical energy, and all three procedures are repeated to run your engine. Your car will need between 10 and 16 volts to start. Yet, factors like temperature will affect the number of volts required to start a car. Since the battery’s chemical reaction is slower in the winter, starting the engine in cold temperatures requires higher power.

Read more:  How to maintain a car battery

## How often should you test your car battery voltage?

Generally, it is advised to check the batteries at least twice a year (every 6 months or 6,000 miles). In your owner’s manual, you’ll discover the recommended interval that applies to your particular car. At least twice a year, you should aim to test your car’s battery. You can test your battery on your own in between garage visits, but your mechanic will test it during normal maintenance and as part of your annual MOT test.

Many automotive batteries include a charge indicator of their own. The top of your battery should have a sight. It often shows a green dot when completely charged. Typically, it will show a yellow dot if it is faulty. It won’t show any color if it needs to be charged. When your battery is running low, the dashboard of the majority of cars will also warn you. You need a voltmeter, often known as a multimeter, to check your automobile battery.

## What are the signs and symptoms of battery troubles?

Here are the most common signs and symptoms of battery troubles:

You can tell how strong your battery is by looking at your car’s headlights. Turn on the headlights when the engine is off if you are having difficulties starting your car. It’s possible that your battery is undercharged if they illuminate dimly. Of course, if you’re doing this in broad daylight outside, you won’t be able to tell how shining your headlights are. Do the Open Circuit Battery Voltage Test as stated in the preceding section, if necessary. If a DMM is not available, you can still accomplish the same thing by using your power windows or wipers. You may have a weak, undercharged, or failing battery if any of these attachments operate slowly or not at all.

### Clicking sound when trying to start the car

A battery that is either undercharged or has too much resistance in the circuit between it and the starter motor will typically make a sequence of clicks instead of the roar of the engine starting.

### Battery dies more often

You may be dealing with a defective battery or one that has reached the end of its useful life if your car battery frequently dies, you routinely need to jump-start your vehicle, or you often charge the battery every week. A good, well-kept battery with a functioning charging system and protection from harsh weather can last up to six years without experiencing any problems. Yet a battery failure trend is like a red flag. The battery might not be able to maintain its charge for very long once it starts to fail. But, make an effort to look into the issue’s origin as quickly as you can. Test the battery, please. It might have reached the end of its useful life.

### Engine cranks slowly

This is typically a further sign that your battery is not fully charged or that there is some resistance in the circuit (corroded, loose terminals, damaged wires) between the battery and the starter motor.

### The battery case appears to be swollen

A bulging or swollen battery case may be an indicator of a frozen battery or a buildup of hydrogen gas (sulfated battery plates) inside the battery case. While a battery might sulfate near the end of its useful life, an alternator overcharging the battery can also boil the electrolyte, turn it into gas, and cause the case to expand. In either case, the battery is probably destroyed.

### Corroded Battery Terminals

A sulfated battery or one that has been overcharged may be the cause of corrosion on the battery terminals which needs to be routinely removed.

## How do you test car battery voltage?

The voltage of fully charged vehicle batteries should be 12.6 volts or higher. This reading should be between 13.7 and 14.7 volts when the engine is running. Start the car and turn on the headlights to test the electrical system if you don’t have a multimeter to determine the battery voltage. If they are faint, the lights are likely being powered by the battery and the alternator is producing little or no charge.

If the lights get brighter as you rev the engine, the alternator may not be delivering enough current at idle to keep the battery charged properly. Your charging system is presumably in good shape if the lights are bright as usual and don’t change brightness as the engine revs. If your battery system has been giving you trouble but the headlight test came back clean, you should investigate if the battery is retaining a charge or if something on the car is draining it.

### Here’s how to test a car battery with a voltmeter:

• Remove the positive terminal cap from the battery. Check and clean up the battery terminals.
• Connect the positive lead of your voltmeter to the battery’s positive terminal. Typically, a voltmeter’s positive lead is red.
• Connect the negative voltmeter lead to the battery’s negative terminal.
• Examine the voltmeter. The voltage should be between 12.4 and 12.7 volts if your battery is in good condition. If the reading is less than 12.4, your battery needs to be charged. Charge the battery slowly, or “trickle charge,” if the measurement is less than 12.2 volts. then double-check. You have excessive voltage if the reading exceeds 12.9 volts.
• To reduce the excessive voltage surface charge, turn on the high beams. An increase in voltage can be a sign that the battery is being overcharged by the alternator. You might want to perform load testing when the voltmeter is nearby.

## FAQs

### How many volts is a dead car battery?

Your battery is fully charged when the reading is between 12.65 and 12.77 volts. You are 75% charged if you have 12.45–12.54 volts, 50% charged at 12.24–12.29, and 25% charged at 11.99–12.06 volts. 11.75–11.89 volts indicate a dead battery.

### Are 12.4 volts enough to start a car?

The battery can still start your engine at 12.4 volts because it is still regarded to be 75% charged. Without the engine running, the battery voltage drops to 12.2 volts, which is regarded as a defective battery that still has the ability to start your car but is no longer able to maintain a charge.

### Are 10 volts enough to start a car?

Your automobile may be started with as little as 11.8 volts, but you can also get it on with 10.8 volts. Yet, since it won’t put more strain on the engine, 11.8 volts is the recommended rating for starting your car.

### Are 14 volts good for a car battery?

The multimeter’s rating should remain between 14 and 14.5 volts when the motor is running. Falling below 14 indicates either a failed alternator or a weak and unstable battery for prolonged vehicle operation.

Attach the positive and negative battery terminals of the multimeter. You can have a faulty battery if your voltage is below 12.6 volts. Start the vehicle now, and check for a revised voltage greater than 10. When the engine is running, if your voltage falls below 5, it is defective and needs to be changed right away.

### What is normal car voltage?

Typically, when talking about the voltage of an automotive battery, we’re talking about a 12-volt battery. When we look more closely, we can see that a car battery’s voltage can range from 12.6 to 14.4. With the engine off, a fully charged automobile battery will rate 12.6 volts.

### How do I know if my car battery is overcharging?

Without the addition of a load (such as the air conditioner or lighting), the voltage will often increase to an average of 14 volts when the car is started. Overcharging is possible if the multimeter registers a reading of greater than 14.8 volts.

### Can a completely dead battery be recharged?

A dead battery can be recharged, and depending on the circumstance, whether you are stranded in your garage and can manage it yourself or you are in the middle of nowhere and require professional, quick, and efficient service in the blink of an eye, a dead battery is typically an easy fix.

### How do you revive a dead battery?

In any case, you must wait until the battery is fully charged before plugging it in. Wait until it is nearly empty, or 5%, and then. After that, re-plug it in and give it another charge. The process should be repeated multiple times to obtain a reconditioned battery.

### How do I know if my 12v battery is bad?

• It’s likely that the battery suffered a short circuit if your battery is reading 0 volts.
• When a battery’s charge cannot rise above 10.5 volts, a cell is dead and the battery needs to be replaced.
• The battery is sulfated if it is fully charged (according to the battery charger) but the voltage is 12.4 volts or less.