How Long Can A Car Battery Power A Laptop

logo by Editorial Staff | Updated on July 11th, 2022

What will your car’s battery be able to do for your laptop when you have no access to power and are traveling to an area where you will not have access to electricity?

I did some research to get a solution…

using laptop in car

A vehicle battery may charge a laptop. But how long can a car battery keep a laptop running?

  • When a vehicle battery powers a laptop for 6.5 hours
  • A 45-watt laptop can operate for 5.1 hours
  • A 60-watt laptop can run for 3.8 hours 

When coupled with an inverter.

How this works

This should work if you presume your car battery is in good condition and hasn’t been used in a long time. When you add the PSU block (the adaptor on your charging cord) to what your laptop will extract from a power source, you get the maximum amount of power your computer can utilize. However, this figure does not always indicate the degree of power necessary. Even if it is less, it may not be easy to achieve. I’ve mostly seen 1/4 of the actual quantity.

However, because so many factors influence laptop power use, we will continue utilizing a universal standard range for our predictions (graphics card, brightness, volume, streaming, and several programs). Laptops with vehicle batteries can be powered in two ways: with an inverter or without an inverter through a DC (direct current) connection.

First, I’ll describe a vehicle battery, how it operates, and how much capacity it has. In addition, I will explain why inverters are wasteful, why a laptop chord is superior to a standard cord, and how DC to DC connections work. Then I’ll go through each laptop model in-depth and describe the different powering options.

How much power can my car battery supply my laptop?

Car batteries are a little complicated because they are “starter batteries” rather than “deep cycle batteries.”

A vehicle battery’s interior composition includes thin lead plates with a larger surface area to conduct amperage faster, allowing it to stress itself (2-3 percent) for a few seconds to start your car. Then, after you start driving, the alternator recharges it.

Discharging a car battery regularly, even below 90%, will harm it. You won’t obtain more than 10 or so total discharges by powering various gadgets or appliances with it.

Deep-cycle batteries, on the other hand, have thicker plates, protective alloys on the plates, and less surface area, allowing them to go through hundreds of full or partial discharges repeatedly, and these would be ideal for powering your laptop if you were thinking about going the 12-volt battery route.

We’ll continue with automobile batteries for this post, but a deep-cycle battery would be a far superior alternative.

Car batteries are measured in cranking amps (CA) or cold cranking amps (CA) rather than ampere-hours (AH) like deep cycle batteries are.

Amp-hours would help us estimate a battery’s potential, but I had to go elsewhere for an answer because they aren’t rated that way.

It all depends on your vehicle, but an average equivalent that appears to be agreed upon by numerous sources in the battery and auto sectors is around 50AH.

50AH is the number we’ll be working within our calculations.

How Can a Car Battery Be Used to Charge Your Laptop?

Of course, this is a question that most drivers wonder about any time they are stranded in the dark when their computers run out of power. For example, assume you’re out camping and your lecturer asks you to resubmit the assignment. Unfortunately, your PC has died, and the task has not been stored on your smartphone.

Because these projects and job reports frequently have deadlines, the experience can be traumatic. However, it does not have to be as unappealing as it may sound. With your automobile nearby, you may turn on the laptop and work on the issue.

There are two methods for connecting the computer to the automobile battery. One, you can connect it directly without using an inverter, or you can use the inverter. The charging time is affected by the choice you select. But, of course, the charging time rises when the inverter is not there.

How to Use a Power Inverter to Charge Your Laptop

A power inverter is the best option when charging your laptop in a car. The inverter simplifies the connection and ensures the safety of both your car battery and laptop. But, of course, this is only feasible if you have the inverter itself. You’ll also need a working cigarette lighter.

As a result, if the one in your car isn’t operating, the charging procedure won’t operate. One thing to keep in mind is that you cannot charge the laptop when the car is idling. As a result, your battery will be depleted sooner than you intended. The following is a step-by-step tutorial on connecting the laptop to charge like an expert.


To find out How Long Can a Car Battery Power a Laptop, follow the steps below.


Instead of connecting your laptop to a household socket, use your car’s batteries while running on DC power. It might be helpful to double-check that you had the correct adapter before starting the process. To get the converter to operate, you’ll need to remove a part of the power cable and replace it with a DC cord. This DC cable perfectly fits the vehicle’s cigarette lighter socket.

What if you don’t have a suitable adapter?

You may get one from any electronics store in your region. It’s also simple to locate these adapters. They are available on Amazon. It is preferable to purchase a universal adapter rather than a model-specific adapter. You’ll avoid the agony of upgrading your laptop’s content after you’ve already topped up another one if you use this strategy.

To begin, connect the adapter to your laptop as follows:

It is ready to begin after you are convinced that you have connected the suitable DC adapter to your laptop charger and links to the other end. Start by inserting the fitting end of the charger into your laptop.

Place the battery in a safe place to avoid damage:

Insert the charging cable into the device’s charging port to begin charging. Next, choose a secure location to store the laptop. Remember that while you’re on the go, you must trust the computer. As a result, you should ensure that it is put on a firm base so that it is not destroyed when moved. Because it gives an excellent area to stow the laptop, an empty seat performs an outstanding job of protecting it.

Connect the DC (or Din) Power Cord to Your Vehicle’s Cigarette Lighter:

Continue charging your laptop with the charger hooked into the computer’s DC port, then plug the DC end into your car’s lighter. You would use this the same way as a phone charger. As a result, no problems should develop.

Turn the key in the ignition and press the gas pedal:

While the charger connects on both ends, the car should be started. Depending on the model, the computer will begin charging as soon as it is switched on. To avoid draining your battery, allow it to continue charging until it is fully charged. If you forget to charge your car’s battery before leaving the house, you may return to a flat battery, needing another trip to the charging station.

How Long Can a Car Battery Keep a Laptop Running?

It’s tough to explain since a car battery may be classified as a “starter battery” and a “deep cycle” battery. A vehicle battery’s interior structure comprises thin lead plates with a larger surface area for carrying electricity. It can stress itself (2-3 percent) for two to three seconds before supplying electricity to your car.

The alternator recharges it once you start driving. You won’t be able to obtain more than 10 or so total discharges by powering various gadgets or appliances with the discharged battery since it will be destroyed.

Deep-cycle batteries also include larger plates, protective alloys on the dishes, and a lower surface area, allowing them to withstand hundreds of complete or partial discharges.

Inverter inefficiency when charging my laptop:

It is the most frequent way for people to power laptop computers when purchasing new ones. However, if you want to keep doing this, you’ll need an inverter to charge your battery. An inverter converts DC battery power into alternating current electricity, allowing you to power your devices with it.

Inefficiencies and heat are dissipated by reversing this power. The average inverter will have a 15 percent inefficiency. Some folks have a lot more, while others have a lot less. For our calculations, we will assume a 15% inefficiency (or an 85% efficiency for “glass half full” persons).

The inefficiency of the Laptop Port:

Even when powered by a wall outlet, laptop power sources are never completely efficient. The wire you’re looking for connects to a rectangular box in the center. It is the power supply unit, transforming the 110-volt AC electricity from the wall to 19-volt DC.

Even though your laptop is plugged into alternating power in your home, it operates on direct current (DC). Inefficiencies in the power supply unit include the inverter, and 10% is a frequent number.


How long can an inverter operate before the battery dies?

The amount of time you may use the inverter to charge a laptop or other gadgets is determined by the electricity you consume.

First and foremost, you must be aware of the device’s wattage and the battery’s reserve capacity. For example, if the battery has a capacity of 100 amp hours and the laptop has a power consumption of 45 watts, the laptop may be charged for 11 hours.

However, you are safe if your laptop has a full charge after 3 hours. Larger loads, such as a television, a desktop computer, and other power-hungry equipment, will deplete the car battery more quickly.

Is it possible for the inverter to drain your car’s battery?

Currently, power inverters of various ratings are available. For example, there are 150W, 240W, 240W, 300W, and 500W. Therefore, a laptop charger with a power rating of 150W or 300W is sufficient when charging your laptop in your automobile.

You might anticipate your battery to drain faster when using a higher capacity adapter than when using a lower capacity adapter. If left connected overnight, the inverter might drain the battery in your automobile. As a result, it’s ideal if you don’t use the inverter to charge when the car is idle.

Will charging my laptop while the car’s engine is turned off harm the battery?

Substant internal damage begins when you repeatedly drain a standard SLI automobile battery to less than 90%. Remember that SLI batteries are not intended to withstand repeated charging and discharging cycles, and it is not the battery’s fault. SLI batteries are not designed in this manner; thus, charging a laptop when the car’s motor is turned off can harm your battery in the long term.

Can an Inverter Damage Your Vehicle?

If your laptop inverter is not connected correctly, you risk harming the cigarette socket. That is why it is essential that you first learn how to connect the inverter before looking for the best power inverter. Then, for ease, you should choose a branded inverter. Unfortunately, those low-cost inverters seen in supermarkets might cause more damage than benefits.

Is it possible to run a laptop off of a car battery?

You’ll need a power converter (a DC to AC inverter) to plug practically any electrical device into your car’s battery. However, you cannot charge your laptop using the wire that came with it while using a DC charger.

Which Battery Type Is Best For Inverters?

Deep cycle marine batteries are, without a doubt, superior to inverters. Standard SLI vehicle batteries, on the other hand, are also suitable, but you must keep the motor running or idling to prevent battery drain.

Is it possible to charge a laptop with a 12v battery?

This charger will not work with laptops since most require a 16V power supply supplied by a 19.5V, 4.5A charger. If the 12-volt battery cannot power the laptop, the laptop will not function. You may use vehicles instead of adapters.


How Long Can a Car Battery Power a Laptop? is a crucial question. Charging the laptop while the car is running is a good technique.

It is necessary to use a vehicle inverter. You must be able to offer a 12V power source to pick an inverter. If you don’t have a long-lasting battery installed, don’t charge your laptop when the car isn’t operating.


Editorial Staff

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