How Long Will a Car Battery Power an Inverter? | Battery Size, Inverter Wattage and Other Factors

The answer is a bit complex. It depends on several factors, like car battery size, the wattage of your inverter, and how much power you are using. If you have a standard car battery, it will likely only be able to power a small inverter for a short time. Larger car batteries can power larger inverters for a more extended period.

Key Takeaways

  • The average car battery will power an inverter for about 10-12 hours.
  • The size of the battery will determine how long it will power the inverter.
  • The inverter type will also determine how long the battery will power it.
  • If you are using an inverter for an extended period, it is best to have a backup car battery or another power source.

In answering your basic questions, we’ll look at different sizes of inverters and batteries and their efficiency. That way, you will be able to determine the suitability of your choices.

What Does a Power Inverter Do, and What Can I Use One For?

A power inverter receives direct current (DC) and converts it into alternating current (AC). It is used to supply AC power to electrical devices that require AC but are operated by DC.

Power inverters are used in a variety of applications, including:

  • To supply AC power to devices that require it, such as computers, printers, and microwaves
  • To operate AC devices such as a battery from a DC power source.
  • To provide a backup power source for devices that require AC power
  • To convert DC power from renewable energy sources, such as solar panels and wind turbines, into AC power

Among these applications is a common question; how long will a car battery power an inverter? That is because of how critical car inverters are. Understanding inverters allows you to learn the facts about a pure sine wave inverter and its power.

inverter with black and red cable

How Long Does an Inverter Battery Last?

How long a power inverter battery lasts depends on several factors, including

  • The type of battery, e.g., lithium battery
  • The quality of the battery, e.g., deep cycle battery
  •  How do you use the battery
  •  How do you maintain the battery

The average lifespan of an inverter battery is three to five years. However, some batteries may last up to 10 years with proper care. The following are some tips to prolong the life of your inverter battery:

  • Use high-quality batteries: Inverter batteries are available in different grades and quality. Using a high-quality battery like a lithium battery will prolong its life.
  • Properly maintain your batteries: Regularly check the water level in your batteries and keep them clean. It would help if you kept the batteries in a cool, dry place.
  • Use your batteries regularly: Batteries used regularly tend to last longer than those not. If you have a battery you don’t use often, charge it fully before storing it.
  • Avoid deep discharge: Deep discharging your battery can shorten its lifespan. Try to keep your battery above 50% charge when possible.

a person putting a battery on its place

Should I Discharge the Car Battery to the Inverter’s Start-up Voltage?

Discharging a car battery to the inverter’s start-up voltage is not right. The car battery won’t manage to supply enough power to start the inverter and may damage the inverter.

When choosing an inverter, it is crucial to consider some of the following factors.

1. The Start-up Voltage of the Inverter

The start-up voltage is the minimum voltage that the inverter needs to start up and run. Most car batteries have a start-up voltage of 12 volts. However, some inverters require a start-up voltage of 24 volts.

If you discharge a car battery to the inverter’s start-up voltage, the car battery will be unable to supply sufficient power to start the inverter. That can damage the inverter and may void the warranty.

2. The Power Requirements of the Plugged Devices

It is crucial to consider the power requirements of the devices that you will plug into the inverter. The inverter must handle the start-up power of all devices you plug into it.

If the inverter is not powerful enough, it will not be able to start up all the devices and may be damaged.

3. The Running Power of the Inverter

The running power is the power that the inverter uses when it is turned on and running. Most car batteries can provide enough power to run an inverter for a short period. However, if you leave the inverter for a long period, the car battery will eventually be depleted, and the inverter will shut down.

In order to avoid damaging the inverter, it is essential to follow the manufacturer’s instructions for use.

battery and inverter

How Many Watt-Hours in a Car Battery?

The average car battery is 105 amps or 12.6 volts. That means the battery contains 12.6 * 105 watt-hours of energy or 1,300 watt-hours. Most cars use between 50 and 100 watt-hours per mile so a 1,300-watt-hour battery will last between 13 and 26 miles.

However, battery size and efficiency can vary significantly between different cars. Electric vehicles tend to have larger batteries than traditional gas cars and more efficient ones as well. As a result, they can travel much further on a single charge.

Some electric vehicles can cover over 200 miles on one charge, while the best gas cars can only travel around 400 miles on a full tank.

How Long Will a Battery Capacity of 12V Last With an Inverter?

How long a 12V battery will last with an inverter depends on several factors, including

  • The size of the inverter.
  • The types of batteries, e.g., lead acid or lithium batteries.
  • The age of the battery.
  • The quality of the battery, e.g., deep cycle battery.
  • How many appliances are being powered.

A rule of thumb is that a 100-watt inverter will draw about 8.3 amps from a 12-volt battery. That means a 100-watt inverter will drain a 1200-watt hour battery in about 2.9 hours.

If you use lead acid batteries, the recommendation is to keep them above 50% battery capacity to prolong their life. And if you are using lithium batteries, you can discharge them down to 20% without harming them.

It’s essential to keep in mind that the actual duration of the battery will also be affected by how much power the appliances are using.

a person placing the battery in the car

Will a Car Power Inverter Drain the Battery?

Yes, a car power inverter can drain the battery if it is not in proper use. If you are using a power inverter to run high-powered electronics, ensure the inverter is in the appropriate size for your power tools and equipment.

Also, turn off the power inverter when it is not in use. Leaving it on will see it continue to draw power from the battery, eventually draining it. It is also wise to use an auxiliary battery or marine deep cycle batteries because of their durability. Alternatively, you can also use a battery bank.

Power inverters are a great option for camping caravans, semi-trucks, and other utility vehicles, where Installing an inverter is a great way to ensure that you have backup power in case of an emergency (see more on pure sine wave inverters).

Just bare in mind that it is important to use the proper gauge wire in order to prevent damage to your inverter and to ensure safety.


How Efficient Are 12V Inverters?

You have some crucial areas to pay attention to when determining the efficiency of a 12V inverter.

  • The inverter’s design. Some inverters are more efficient than others.
  • The value of the parts used in the inverter. Higher-quality components will result in a more efficient inverter.
  • The operating conditions of the inverter. If the inverter operates under conditions that are not ideal, the efficiency will be lower.
  • The age of the inverter. Older inverters tend to be less efficient than newer ones.
  • The brand of the inverter. Some brands are known for their high-efficiency inverters, while others are not.

Necessary Safety Precautions While Running an Inverter

A few essential safety precautions are to keep in mind while operating an inverter.

  • Always read the manufacturer’s instructions carefully before using the inverter.
  •  Never operate the inverter near flammable materials or in an enclosed space.
  • Connect the inverter to a rated battery for the inverter’s wattage output. Overloading the inverter can damage the unit and pose a fire hazard.
  • Always disconnect the inverter from the power outlet before you start any repairs or adjustments.

These simple safety precautions can help ensure your power inverter runs safely and efficiently.

inverters in different sizes


1. How Long Will a Battery Voltage of 12 Run a 200-Watt Inverter?

How long a 12-volt battery will run a 200-watt inverter depends on many factors, including

  • The type of battery, e.g., lithium or engine start batteries.
  • The age of the battery, e.g., the status of the battery terminals.
  • The temperature.
  • The wattage of the inverter.

The lifespan of a 12v battery also varies depending on how you use it.

2. Can You Use an Inverter While Driving?

Yes, you can use an inverter while driving. However, you should pay attention to the following points.

  • Make sure the inverter is grounded correctly.
  • Stay within the wattage rating of the inverter.
  • Be aware that some electronic devices may not work properly when connected to an inverter.

3. Can I Use My Power Inverter When a Car Engine Is Turned Off?

Using power inverters when the car engine is off is perfectly safe. That is one of the most common ways that people use power inverters.

However, it is vital to remember that the inverter will be drawing power from the battery. So, you must confirm the battery voltage is fully charged and in good condition before using the inverter.

4. Can an Inverter Charge Its Own Battery?

Yes, an inverter can charge its battery. That is because inverters typically have a built-in charger that you can use to replenish the battery’s charge. Inverters that have this feature are often called “battery chargers.”

Leave a Comment