General Question

z_malloc's avatar

Charging laptops in cars. Is it safe?

Asked by z_malloc (73points) June 14th, 2008

I have a macbook and a power inverter. I have done this before, and it works fine. However, I have never really been certain about how damaging it is to the batteries involved both laptop and vehicle.

My understanding is that if the car is running, the voltage is higher and you run less risk of damage from dipping too low. But you increase the chance of damage from voltage spikes. If you charge while the car is off, you get the opposite. So if what you are charging doesn’t draw a lot of power, clearly vehicle off is the smart thing to do. But I am going on a long trip, so the point of my question is.

How safe is it to charge a macbook with a 60watt, 16.5v, 3.5a power supply in a car that is running?

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12 Answers

waterskier2007's avatar

it should be ok, but im pretty sure that u can buy an adapter for your charger to go right to a car cigarette lighter. im not 100 percent sure though so dont take it as gospel

arnbev959's avatar

This is what my physics final on monday is going to be like. If I weren’t going to fail the test, I’d be able to figure it out.

FiRE_MaN's avatar

It is fine I’m pretty sure the power that it is taking away from the car is about the same as to power the headlights.

ninjaxmarc's avatar

charging your phone in the car is damaging to your battery what more a laptop.

XCNuse's avatar

I personally wouldn’t, cars have an alternator, which pumps out electricity from your motor’s belt drive, and remember that you engine doesn’t run at the same speed full times, so your volts are constantly varrying, to an extent chargers do a good job of this, but not fully, so not only will you be shortening the life span of your charger, but also the battery in your laptop.

Like I said, you can do it, but I personally wouldn’t.

ninjaxmarc's avatar

alternative run your laptop without a battery in the car charge it outside of your car.

FiRE_MaN's avatar


Sorry to say but you are wrong. The laptop takes the power from the cars battery! The only bad thing that could come out of charging your laptop in you leave it charging over night your battery will probably be dead.

XCNuse's avatar

Well there’s another way of looking at this, it’ll put a dent in your car’s battery to by draining and recharging it more than the norm.

and yes, the worst truth could be that your battery lands up dieing and you’re stranded on a business trip without a car battery.

ordosingularis's avatar

It’s no problem as chargers have voltage regulators. The only issue is drawing too much current through your cigarette lighter port which could trip of fuse or cause overheating issues.

XCNuse's avatar

shows how much i pay attention to electronics in a car, all i care about is all the metal stuff, get me into electricity and everything goes in one ear and out the other lol

FiRE_MaN's avatar

haha that’s really all I know about cars I saw this topic and said hey! I can answer this. And I needed something to rant about.

IchtheosaurusRex's avatar

You won’t have a problem doing this if you are using a power inverter to drive the charger that came with your computer. Even if you’re using a cheap, square-wave inverter, the charger will regulate the current being delivered to your notebook’s battery. The only problems I’ve heard of come from people using the Radio Shack universal laptop battery charger, which does not use AC inversion, and is poorly regulated. Your setup is just fine.

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