How Big of an Inverter Can My Car Handle? | We Explained How to Determine This

An inverter converts power from a battery-powered electronic to a voltage suitable for a car. To figure out how big of an inverter your car can handle, you need to look at its current voltage and how much power it requires. Most cars today have a 110v inverter, and the more significant the inverter, the lesser the power. 

Key Takeaways:

  • Determining the appropriate inverter size depends on the load it should supply.
  • To determine the load on the inverter’s continuous wattage multiplied by 1.3 to 1.5. 
  • You measure the size of an inverter in a kilovolt-ampere (kVA).
  • The higher the inverter kilovolt-ampere, the more power it can supply. 
  • An inverter model and manufacturer duty cycle, peak power, and in some instances, its average power.

So, how big of an inverter can my car handle? This article covers the basics of the car power inverter, its benefits, and its implications for your battery. 

How Big of an Inverter Can My Car Handle?

The size of the inverter should depend on your power needs. Before you buy and install the inverter, determine your inverter size. It keeps you from overtaxing the car’s electrical system. Putting an inverter in your car means it can only use as much power as the car’s electrical system lets it. 

To figure out how much power you need, you must know what you plan to plug into the new inverter. If you need to plug in one device at a time, then that’s what you need to consider. The more devices you add, the more complicated the situation becomes. Luckily, it’s a relatively simple calculation you’ll need to make. 

Manufacturers usually make the wattage information available on the electronic device, but it may sometimes show amperage and voltage ratings. When you find the wattage information, you need to sum it up. Whatever figure you get shows you the smallest possible inverter size to suit your needs. However, it’s advisable to add 10–20 percent of the total on top of your figure before buying a new inverter

Man carrying a car inverter

Determining the Size of Car Inverter to Use in Your Car

Once you figure out the devices you intend to use, the next step is to determine the size of the inverter you should buy. For instance, you may want to plug in a printer, television, light bulb, or laptop. 

The first thing you need to do is to figure out each device’s wattage and then add them.

A printer uses 50 watts, an LCD TV 250 watts, a light bulb 100 watts, and a laptop 90 watts. The total wattage is 490 watts. The resulting subtotal after the addition gives you a baseline you can work with. However, as mentioned earlier, you should add 10-20 percent as a safety margin. 

490 Watts + 10% (Safety Margin) = 539 Watts (The minimum size of inverter you need)

If you want to run all four power tools or devices simultaneously, the above number tells you the inverter you want to buy must have a continuous output of at least 539 watts. You can do some basic math if you’re unsure of your device’s power requirements. 

The inputs appear on the power brick for devices with an AC power/DC power adapter. On other devices, you’ll find the label somewhere out of sight. 

The fundamental formula to note is:

Volts x Amps = Watts

In this case, you need to multiply the volts of each of the devices with the input amps to get the wattage. In other cases, you’ll find the device watts online. Alternatively, you can look into the AC power supply. 

Factors That Affect the Size of Inverter You Can Use to Power Your Car

Several factors affect the size of the inverter needed to power your car:

  • Power: Power demand depends on the gadgets in the car and the car’s power.
  • Load: A smaller car battery voltage can’t handle a more significant load because the total load determines the car battery size. 
  • Size: Your car’s battery depends on the car’s size. So, bigger cars have bigger batteries. 
  • Weight: An inverter must be powerful enough to lift the car battery weight because car batteries are heavy.

An inverter in a car

What is the Danger of Using “Too Big” of an Inverter? Can an Inverter Damage the Car?

Having a bigger inverter than you need may cause the following problems:

  • There’s the risk of draining the vehicle battery flat.
  • When a high-power inverter draws a higher current rating than the one connected to the battery, it melts or burns the car wiring.
  • It may cause the socket of the cigarette lighter to stop working because currents greater than 10-15 amps can blow the fuse. 

Can a Car Battery Run a 3,000-Watt Inverter?

A car battery can’t handle a 3,000-watt inverter because of its high power draw for a full-load car. This wattage requires dedication in wiring to give it the ability to control the full load of 250 amps (3,000/12). It also means you must fuse the car adequately to prevent damage during a short circuit. The power inverters drain the battery flat when sustaining the power draw, making the car not start. 

How Long Does a Car Battery Take to Run on a 300-Watt Inverter?

The power inverter size doesn’t determine how long the battery lasts. Instead, your vehicle’s RPM and load size determine that. A standard car battery works at 12V with a capacity that ranges from 600 to 900 watts per hour or 50-75 amps per hour

To keep your battery running for longer, do the following:

  • Confirm the specs of your alternator to determine the current it provides.
  • Connect higher loads only with increasing RPMs (above 1500 RPM) and when driving at a higher speed
  • Power smaller loads between 120 and 150 watts at a slower speed.

A car inverter in a car plugged in

Benefits of Having a Power Inverter in Your Car?

A pure sine wave inverter provides your car with a reliable power source as and when needed. Some of its benefits are:

  • Creating a reliable power source when camping or hiking.
  • Powers entertainment devices in your car.
  • Allows you to use the car as an emergency power source, e.g., during blackouts.
  • It enables you to charge electronics from anywhere. 

Do Power Inverters Damage Your Car?

Under the right conditions, a car battery lasts between 3 and 5 years. Its lifespan depends on many things, like how often it has energy bursts and the weather. However, there’s a need for preventive measures if you’re using a power inverter in your car. Such actions keep the inverter from damaging the car battery. 

A silver car inverter

Use the Inverter Only With a Running Car Engine

The inverter requires a high-power load from the car battery. As the engine runs, the alternator keeps charging the battery and allows you to add the load. You don’t have to discharge your battery. Otherwise, you’ll drain your battery and have no power to turn on the car. 

Avoid Powering High-Demand Devices

Keep in mind that if an electronic demands a higher power amount, it’ll leave the battery to discharge at a higher speed than the alternator can charge it. A power inverter may leave you with a drained or dead battery. In this case, solar power is also a great supplementary charging option for your battery. 

Understand the Cigarette Lighter Socket Power Limits 

Power inverters used in cars go up to 150-180 watts. Most of these inverters plug into the car’s auxiliary power outlet, which is also called the cigarette lighter socket. To stay on the safe side, use a power inverter between 150 and 180 watts until you’re confident that you have 20-amp sockets.

Speeding blue car on road


What’s the Biggest Inverter I Can Put on My Car?

The biggest inverter you can put on your car depends on your car electrical system. A 15 amp socket at 12V can safely run 1.5 amps @ 120V AC (150 – 180W), while a 20 amps socket at 12V can run 2 amps @ 120V AC (200 – 240W). To be safe, you should only use 150 – 180W power inverters through this outlet unless you are certain you have 20 amp sockets.

Can You Leave Your Inverter On All the Time?

Yes you can leave your power inverter on all the time. It is possible but not advisable. When you keep the inverter on, it will start draining the battery quickly. Even if you’ve not connected an electronic appliance to the inverter, the battery will draw the power and start draining swiftly.

Why Does My Inverter Drain My Battery?

Your inverter drains your battery due to a high load. “Load” refers to the electrical devices connected to the inverter, such as TVs and light bulbs. A high load means the inverter must supply a lot of power. As a result, it will draw a huge amount of power from the battery, eventually draining it.

What are the Problems of an Inverter?

Some challenges you’ll experience with an inverter include:

  • Decline to switch on.
  • Continuous alarm blaring.
  • Low backup capability.
  • The battery fails to charge.
  • The inverter makes noise.

Where Should I Put the Inverter in My Car?

You’ll install your inverter into your vehicle’s fuse box. Locate your car’s fuse box under the hood, and ensure enough room to fish wires through your ride’s mechanical components. Use a new fuse, of course, when installing your inverter.

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