How to Safely Charge a Laptop in the Car

If you’re going out on a long road trip and are taking a laptop with you for work, to watch movies, or play video games then you’ll need to keep it charged while in the car.

This post shares tips on how to safely charge and use the laptop, including how to avoid overloading the 12V cigarette lighter socket wiring, the power rating of the DC-DC converter to use, and how to minimize the drain on the car’s battery.

Should you Charge a Laptop in from the Car Battery?

Yes, you can charge a laptop from your car safely provided that the inverter or DC-DC converter you plug the laptop into can supply the right amount of power (watts) it needs to run.

You can find the laptop’s power rating (watts) on its power brick.

It is usually listed in watts or volts and a current value, for example, you may have 70 watts or a DC voltage and current value such as 19.5V, 3.5 A on the laptop’s power brick.

The power rating of the inverter or DC to DC converter should match the laptop’s power consumption or higher not to overload the inverter or converter.

Additionally, keep in mind that you can only draw up to a certain power limit from the cigarette lighter socket usually 120W or 150W at 12V or 24V (consult your car owner manual).

Therefore, do not connect an inverter or converter whose power draw exceeds what the cigarette lighter socket can handle.

Why Some Laptops May Not Charge with a Power Inverter

Some laptops may not charge when plugged into some modified sine wave inverters. Try using a pure sine wave inverter or a better quality modified sine wave inverter instead.

Does it drain the Car Battery?

Yes, charging a laptop from the car drains the car battery if the car engine is switched off and the laptop is plugged into the cigarette lighter socket, whether through an inverter or DC-DC converter.

To prevent the battery from draining, start and keep the car engine running. In this case, the alternator acts as the first source of power to charge the laptop, and the battery is only drained should the combined power draw (of all switched-on accessories) exceeds what the alternator can supply.

How Much Electricity a Laptop Consumes?

You can find out how much power a laptop consumes by checking out its power rating. Check the label on the laptop’s power brick.

With that said, you’re likely to find most laptop power adapters with power consumption values of between 45-80 watts with gaming laptops consuming more.

In practice, actual power draw depends on a number of variables -whether or not it is charging the battery, how bright the display is set to, and whether the programs it is running (games, graphics) require considerable power draw by the processor or not.

How long can I charge my laptop from the car battery

You can expect the laptop to charge within 1 – 3 hours depending on the capacity of the power inverter, DC-DC converter, the extent to which the battery is drained, and the battery capacity.

How to Charge the Laptop

To charge your laptop in the car, you can use a DC-DC converter (preferred) that is plugged into the cigarette lighter socket with a connector that then plugs into the laptop directly.

Make sure you purchase a good-quality converter designed for your laptop. There are several incidents on record where underrated converters have overheated and blown the car fuse.

You can also use a power inverter. To use this, you need the laptop’s AC power adaptor.

Using a power inverter is less efficient than a DC-DC converter as it uses up more power to supply the laptop power than the inverter.

You may also be interested in this post: What size of inverter to use with a gaming laptop

Related questions

Can you Charge a Macbook from the Car battery?

Yes, you can – check for an available car charger kit from Apple or charge it by plugging the MacBook pro’s AC adapter into a good quality power inverter with a cigarette lighter socket plug.

Final Word

You can safely charge a laptop in the car using a DC-DC converter (more efficient) or a power inverter.

Whichever device you use, make sure it is sized to handle the power draw of the laptop and can be safely plugged into the cigarette lighter socket without drawing currents in excess of what the wiring can handle.

Hope this helps.

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