How Many Watts Does A Car Battery Have? Car Battery Wattage. 12v car battery capacity

When to replace the 12-Volt car battery?

The 12-volt battery in your vehicle needs to be replaced when its capacity drops close to or below the safe level. The capacity of the battery is the ability to hold charge. If you suspect that your battery is getting weak, have it tested at your next service. Your repair shop can test the actual capacity or Cold Cranking Amps (CCA) of your battery and compare it to its CCA rating. If the battery fails the test, have it replaced. In most cars the battery is replaced after 5-7 years.

How it works: the 12-volt battery in your car stores the electric power to start your engine. When the engine is running, the alternator generates electric power and recharges the battery.

A new battery has full capacity or the ability to hold charge. It can store enough charge to power the electrical system when the car is parked for days and turn over your engine multiple times to start it. Over time, however, the battery loses its capacity. Motorists often find this on one of the cold mornings when the vehicle doesn’t start and needs to be boosted. For this reason, the best time to have the battery tested is before the cold season.

How long do car batteries last?

Medium-size 12-volt car batteries, like the one in the photo, last on average for 7 years. Smaller batteries, like in some Honda vehicles, last for about 5 years. Larger batteries in many trucks last for 8-10 years. In our experience, a battery lasts longer if the vehicle is driven daily and the battery is kept fully charged. The life of the battery also depends on the outside temperature: if the climate is too hot or too cold, the battery’s life will be shorter. Also, if the vehicle is parked for extended periods of time, the battery can fail prematurely. The quality of the battery matters too. We have seen cheap batteries failing after 3-4 years.

How can the battery capacity be tested?

Testing the battery capacity with a battery tester.

The battery capacity is measured in CCA or Cold Cranking Amps. A new average-size battery like the one in the top photo is rated between 520 and 650 CCA.

Many automotive repair shops can test your battery with a battery tester (in the photo). The battery tester can measure the actual CCA and compare it to the new battery CCA rating. The battery CCA rating is marked on the battery itself, see the photo.

The battery tester can also test the alternator and the charging system. Read more about the charging system: When does the alternator need to be replaced?

Battery and charging system test printout

The battery and charging system test, also known as the AVR test, costs from 20 to 50. Some auto parts stores such as Autozone or O’Reilly Auto Parts offer a battery test at no charge. Many car dealers and repair shops often offer a free battery test as a part of a larger service or a seasonal promotion.

After the test, you might get a printout showing the battery CCA rating and the measured CCA. The printout will indicate if the battery should be replaced or if it’s in good condition. It may show that the battery needs to be recharged first and then re-tested. See the sample printout in the photo.

Can you test a battery with a voltmeter?

Testing the battery state of charge with a voltmeter.

The battery voltage is an indicator of the state of charge of the battery. A fully charged battery should read 12.6 volts or more with the engine off. If the battery shows less than 12 volts, it’s completely discharged. However, even an old failing battery with low capacity will show 12.6 volts when fully charged.

To test the capacity of the battery, the battery voltage needs to be tested under load. The longer the battery can hold the voltage under load, the larger its capacity.

For example, if the fully-charged battery voltage with the engine OFF and headlights ON drops from 12.6 volts to less than 11.5 volts in a couple of minutes, the battery’s capacity is low. If the battery voltage with the engine OFF and headlights ON stays close to 12 volts even after 10 minutes, the battery is good.

Does the 12 Volt car battery need any maintenance?

Corroded vs serviced battery terminal.

Most modern cars have maintenance-free batteries. When you take your car for an oil change, your mechanic will inspect the battery visually. If the battery terminals show corrosion as in the photo, your mechanic may recommend servicing the battery terminals.

The battery terminal service costs from 25 to 60. It includes cleaning the battery posts and terminals and applying a protective spray or grease.

How much does the battery replacement cost?

A new car battery costs from 140 to 550 and your dealer may charge another 50-65 to have it replaced. Replacing a car battery as a do-it-yourself project is not very difficult, but the battery is heavy (30-45 lb). Lifting it out of the car can be hard on your back. An old battery is often covered in electrolyte, which is very acidic and can burn your clothes or skin. Here is a video from O’Reilly Auto Parts. Our recommendation is to leave it to the pros. Some cars require a specific battery type. To make sure, check the vehicle owner’s manual or consult with your local dealer.

Where to recycle an old car battery? Some automotive repair shops and car dealers will accept your old battery for recycling. For example, you can find the nearest place to recycle your old battery at the Interstate Batteries website.

How long is the battery warranty? In most cars, the battery is covered under the basic bumper-to-bumper warranty. In some cars, the battery coverage is pro-rated. This means, for example, the labor might be fully covered, while the part might be covered 100 percent within the first year, 50 percent within the second year and so on. You can find the warranty coverage details in your Warranty Guide brochure or on the manufacturer’s website.

How to boost your car when the battery is low on charge? To boost you car, you will need a portable booster or jumper cables to boost from another car. Your owner’s manual has the proper instructions. Be careful, if the booster cables are connected to wrong terminals, it may cause a big spark and some fuses could be fried.

How long does it take to recharge a good battery that is low on charge? If the battery is still good, 20-40 minutes of running the engine or driving is usually enough to recharge it. However, be aware that in some cars with electric power steering, the steering assist might not work properly until the battery is sufficiently charged. This can make driving with a low battery dangerous. If a good battery has not been used for an extended period of time and is completely drained, it might need longer time to recharge.

How does the car battery work?

Panasonic 12 Volt car battery.

The car battery works by storing the chemical energy that can be converted into electric energy. While charging, the opposite conversion happens.

Most cars have lead-acid batteries that are made of six cells. Each cell has lead plates connected to the negative terminal of the cell and lead-oxide plates connected to the positive terminal of the cell. Each cell produces 2 volts. Six cells are connected in series to produce 12 volts. Cells are filled with an electrolyte (diluted sulfuric acid).

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How Many Watts Does A Car Battery Have? Car Battery Wattage

If you are wondering about car battery wattage, this article will help you. While manufacturers do not show this figure on their products, there is a way to work the numbers on your own.

Don’t rush. Go through the following information and instructions carefully to ensure you fully understand the terms and calculations.

How Many Watts In A Car Battery?

On average, a car battery comes with 12.6 volts and 105 amps, equaling 1323 watts.

What Does The Watt Number Means For A Car Battery?

Before getting to know the number of watts in a car battery, you need to understand two terms: car battery wattage and watt-hour.

Watt is a power measuring unit that indicates how much power is in a device. It’s often used with electrical devices like machines, motors, or heaters.

Meanwhile, a watt-hour is a unit used to measure a device’s energy usage. The number of watt-hours also illustrates the power capacity, meaning how many watts of power a device can deliver in an hour.

Both watt and watt-hour have variants for measurement, such as megawatt, kilowatt, kilowatt-hour, megawatt-hour, etc.

When discussing the power of a battery, watt-hour is the proper unit to use.

How To Calculate A Car Battery’s Watt-Hours?

Manufacturers do not print a battery capacity on its case. However, they provide certain specifications that you can use to calculate the watt-hours in a car battery, including voltage (V) and ampere-hour (Ah).

  • Battery voltage: The electric potential difference between the battery’s positive and negative sides. The typical car battery has 12 volts, divided into six cells.
  • Ampere-hour: This unit measures the battery charge that allows 1 ampere of current to flow in an hour. In another word, ampere-hour indicates the amount of energy a battery can supply for one hour.

You can easily find these specifications on the battery case. To figure out the car battery watt-hours, rely on the following formula:

Ampere-hour x Voltage = Watt-hours

For instance, the car battery in the following image features a voltage of 12V and an ampere-hour rate of 4Ah. The watt-hour rate of this battery is 4 x 12 = 48 watt-hours (Wh).

How Many Watts Are In A 12-Volt Battery?

To be exact, the average automotive battery has a voltage of 12.6 volts, consisting of six 6.1-volt cells. At the same time, the average ampere-hour rate is 105 amps.

By calculation, the batter would have: 12.6 x 105 = 1,323 watt-hours.

It’s worth noting that while the 12V car battery voltage has become a common standard for automobiles, the ampere-hour rate varies a lot among brands and models. Therefore, it’s best to check out the specifications shown on the case.

How Many Watts Does A Car Use?

The answer to this question depends on what battery is installed in your vehicle. The wattage is determined by not only the size of the battery but also the type of battery.

To know how many watts a car uses, you also need to do some calculations based on the ampere-hour and voltage rate of your car battery. Then, using the same formula, you can determine how much electricity your car uses.

When it comes to the type of battery, it can be said that lead-acid batteries are less efficient than lithium-ion batteries. That’s why a car with a lead-acid battery will use more power than one with a lithium-ion battery.

How Many Watts Can A Car Battery Supply?

The number of watts a car battery supplies is not the same for every vehicle. As mentioned, a typical car is designed to have a 12-volt battery. However, the ampere-hour rate is different from one battery to another.

For instance, with a 12V 100Ah battery, it’s translated into 1200 watt-hours of power. With this power capacity, the battery can produce 1200 watts in an hour, 600 watts in 2 hours, or 400 watts in 3 hours.

It means there isn’t a definite number regarding how many watts a car battery can supply.

On the other hand, a battery’s power supply is affected by external factors, such as the temperature. In the winter, it produces less power, which is why it takes longer to start your car than in the summer.

How To Choose Car Battery


One of the first things to decide when shopping for a car battery is whether you want a deep cycle or an AGM battery, depending on your needs.

An AGM or a starter battery delivers a huge amount of power to help you start the engine. The alternator then recharges it. However, it cannot endure several discharge/recharge cycles, so improper use can reduce the battery life significantly.

Meanwhile, a deep-cycle battery gives a steady amount of power over a period of time. Batteries using this technology don’t suffer from damages from repeated discharges and recharges. As a result, they are more durable.


When browsing car battery models, power is the next factor to remember. Here, you must check out the reserve capacity (RC) and cold cranking amps (CCA).

CCA indicates the battery’s starting power, which must match your car’s requirements. RC shows how many minutes of reserve power is in the battery at a given load, which ensures all accessories in the car are powered.


There are maintenance-free batteries and maintenance-required ones. The former cost a lot more, but you don’t have to worry about electrolyte monitoring.

Though the other type is cheaper, you have to check the electrolyte level and top it up when needed. It calls for more effort and attention from you.

Specifications (Amps per Hour and C20)

Amp-hour (C20) is an important specification to consider if you want to buy the best battery for your car. It illustrates the amount of energy stored to supply for 20 consecutive hours at 80 degrees F without dropping to under 10.5V.

Related Questions

Can You Power A House With A Car Battery?

Yes, you can. However, you will need a power inverter to match the battery’s current with your house’s current.

Can You Use A Car Battery As A Generator?

Yes, you absolutely can. Your car battery can act as a power bank for you to charge your devices. Yet, you need a power inverter made for 12V batteries.

How Many Watts Is A 12V 100Ah Battery?

To answer this question, you need to multiply the voltage by ampere-hours. You will get: 12 x 100 = 1200 watt-hours. A 12V 100Ah battery holds 1200 watt-hours of power.

How Many Watts Does A Car Battery Charger Use?

To charge a car battery, a 10A charger uses less than 200 watts, while a 25V charger would use less than 500 watts.


Overall, the general formula is multiplying the volt by the ampere-hour to determine how many watts are in a car battery, how much electricity your car uses, or how much power it can supply.

You should quickly find these specifications on the battery case and do the math within seconds. If you are looking to replace your car battery, it will help to know these figures in order to select the right model for your vehicle.

How Many Watts to Charge a Car Battery?

A car battery typically requires between 6 and 12 volts to charge. The average charging rate for a car battery is between 1 and 2 amps, so it would take between 3 and 6 hours to fully charge a dead car battery using a standard household outlet.

If your car battery is dead, you’re going to need to charge it up before you can hit the road again. But how many watts do you need to charge a car battery? The answer depends on the size of your battery.

A standard car battery is about 60 amp hours, which means it can hold about 60 watt hours of energy. To fully charge such a battery, you’ll need about 75 watts of power. However, if your car has a larger battery (like some electric vehicles do), then you’ll need more power to charge it.

In that case, you might need upwards of 200 watts or more. Of course, these are just estimates. The actual amount of power you’ll need will vary depending on the type of charger you’re using and other factors.

So if you’re not sure how many watts to use, it’s best to consult with a professional or read your charger’s instructions carefully.

How Many Watts Does It Take to Recharge a Car Battery?

A car battery typically requires between 6 and 12 volts to recharge, so the number of watts required to recharge a car battery depends on the voltage of the battery. For example, a 6-volt battery would require about 30 watts to recharge, while a 12-volt battery would require about 60 watts.

How Many Watts Does a 12V Car Battery Charger Use?

A 12v car battery charger typically uses between 10 and 20 watts of power. The specific wattage will depend on the make and model of the charger, as well as the voltage of the battery being charged. For example, a charger for a lead-acid battery will use more power than one for a lithium-ion battery.

When choosing a 12v car battery charger, it is important to select one that is compatible with the type of battery in your vehicle. Chargers are not all created equal, and using an incompatible charger could damage your battery or cause it to malfunction.

How Many Watts Does a 10 Amp Car Battery Charger Use?

A 10 amp car battery charger uses 1,000 watts.

How Many Watts to Trickle Charge a Car Battery?

A trickle charger is a great way to keep your car battery charged and ready to go. But how many watts do you need to trickle charge a car battery? The answer depends on the size of your car battery.

A standard 12 volt car battery typically requires between 10 and 20 watts to trickle charge. However, if your car has a larger battery, you may need up to 30 or 40 watts. To be safe, it’s always best to consult your car’s owner manual or a professional mechanic to determine the specific wattage requirements for your vehicle.

Once you know the proper wattage, simply choose a trickle charger with that output and follow the instructions included with the device.

How Many Watts to Charge a 12V Battery?

Are you wondering how many watts to charge a 12V battery? Well, the answer depends on a few factors, including the type of battery and the charger you are using. For example, if you are using a lead acid battery, it will require about 10-15 watts to charge fully.

On the other hand, if you are using a lithium-ion battery, it will only require about 5-7 watts. Of course, these are just general estimates and your actual results may vary depending on the specific circumstances. So, be sure to consult your owner’s manual or ask an expert before attempting to charge your battery.

How Many Watts in a 12 Volt Car Battery?

Are you looking to buy a new car battery and want to know how many watts it has? 12 volt car batteries are the most common type of battery used in cars. They usually have between 60-80 Ah (amp hours), which means they can provide between 720-960 watt hours of power.

Watt hours is a measure of how much energy the battery can store, so if you’re looking for a powerful battery, make sure to check the watt hours!

How Many Watts in a Car Battery?

How many watts are in a car battery? This is a question that is often asked by those who are looking to purchase a new battery for their car. The answer to this question can vary depending on the type of battery that you have in your car.

For instance, if you have a lead-acid battery, then the number of watts will be different from if you have a nickel-cadmium battery. In general, however, most car batteries contain between 12 and 30 watt-hours per cell. This means that if you have a lead-acid battery with 12 volt and 20 amp hour rating, it will contain 240 watt hours.

Similarly, if you have a nickel-cadmium battery with 24 volt and 5 amp hour rating, it will contain 120 watt hours. Of course, the capacity of your car’s battery will also affect the total number of watts that it can provide. A smaller battery will obviously provide less power than a larger one.

In terms of how long a car battery will last, this again depends on the type of battery as well as its size. A lead-acid Battery typically lasts for around 3 to 5 years while nickel-cadmium batteries tend to last for about 2 years. Ultimately, however, it is important to remember that all batteries degrade over time and need to be replaced eventually.

How Many Watts Does a 20 Amp Battery Charger Use?

A 20 amp battery charger uses 4000 watts. This is because the charger uses a voltage of 220 volts and 20 amps to charge the battery. The wattage is calculated by multiplying the volts by the amps, which gives you 4,400 watts.

How Many Watts Does a 40 Amp Battery Charger Use?

A 40-amp battery charger uses between 3,840 and 4,800 watts of power. This range covers most types of battery chargers on the market today. The average cost to charge a car battery is about 0.15 per kilowatt-hour, so it would cost you between 0.58 and 0.72 to charge a 40-amp battery.

Using a car battery charger

Frequent short trips, with constant stopping and starting, make your battery work very hard, especially in winter when heater, headlights. heated Windows and wipers may be working most of the time.

Eventually, because more current is being drained from the battery than the alternator can put back, the battery will not have enough power left to turn the starter motor. A battery in that state of discharge is said to be flat.

A flat battery can be avoided if you have a battery charger. a relatively cheap, but worthwhile accessory.

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It uses mains current to replace the battery’s lost charge through positive and negative leads that clip to the corresponding battery posts.

An average car battery has a capacity of around 48 amp hours which means that, fully charged, it delivers 1 amp for 48 hours, 2 amps for 24 hours, 8 amps for 6 hours and so on.

A basic charger usually charges at around 2 amps. and so needs 24 hours to deliver the 48 amps needed to fully charge a flat, 48 amp hour battery.

But there is a wide range of chargers with different charge rates on the market. from 2 to 10 amps. The higher the charge output, the faster a flat battery is recharged. Fast charging, however, is undesirable as it can buckle the battery plates.

The loads imposed on your battery may be gauged from the amount of current used by the various electrical components: headlights take about 8 to 10 amps, a heated rear window about the same.

Theoretically, a fully charged battery, without taking in current from the generator. should work the starter for about ten minutes, or the headlights for eight hours, and a heated rear window for 12 hours. As the battery nears full discharge, the lights gradually grow dimmer and finally go out altogether.

There are also causes other than short trips and cold weather which can affect the state of your battery. Failure is more common on cars equipped with a dynamo rather than an alternator. because the alternator produces more electricity and charges better at low engine speeds (See How the charging system works ).

The answer in all these cases is frequent testing with a hydrometer (See Checking the batteries ) to see how much capacity is left in the battery, and using a battery charger to top up its charge when necessary.

Connecting a battery charger

Always check the electrolyte level before connecting the battery to the charger. Top up if necessary (See Checking the batteries ) and clean the battery posts.

If there is a power point handy, the battery can be left in the car, so long as the charge rate is only 3 or 4 amps.

However, if the car has an alternator, disconnect the battery terminals beforehand: otherwise some alternators. generally the older type. can be damaged.

If separate cell caps are fitted, remove them for ventilation. Leave a trough cover on, unless the charging rate is high. Clamp the positive lead from the charger, usually coloured red, to the positive battery post. Clamp the negative (-) lead, usually black, to the negative terminal.

Plug the charger into the mains and switch on. The indicator light or gauge ( ammeter ) will show that the battery is being charged.

The gauge may show a high charging rate at first, but this drops gradually as the battery becomes charged.

If it was very flat, charging is likely to take a long time; check periodically with a hydrometer, while continuing the charge.

In the final stages, the cells bubble and give off gas. If any of them begin gassing before others, or do so more violently, the battery is probably defective and should be checked by a garage or battery specialist.

Types of car battery charger

A basic home battery charger incorporates a transformer and rectifier, to change the mains 110/220 volt alternating current to 12 volt direct current. and allows the mains supply to provide a charging current at a rate determined by the state of the battery.

In the case of a battery in good condition, the rate of charge may be around 3 to 6 amps with a normal home charger.

A battery at the end of its useful life may not accept any recharging, and will not, in any case, hold a charge.

Some chargers are fitted with a high and low (Hi-Lo) switch to give a choice of two charging rates. typically 3 or 6 amps. in case you want to give the battery a short overnight boost at 6 amps rather than a longer charge at 3 amps.

Many have a charge indicator which may be a warning light, or a gauge showing the charge rate in amps.

Read more

How to test a car battery

If your car’s instrument panel includes an ammeter. it will tell you how well the charging syst.

Checking the batteries

Most car batteries are sealed for life. apart from a small vent hole which allows gas to e.

Checking a starter circuit

If the starter does not turn the engine although the car battery is in good condition, the.

How to test electrical circuits

If there is trouble without an obvious cause in any electrical component, test the circuit to f.

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