plugging a laptop into a car cigarette lighter
 

Yesterday I bought one of these little 85W inverters. See here
http://www.bestbuy.ca/catalog/prodde...72&catid=21389

When I got home I wondered if it would really work or would just overload the unit. How many watts to laptops typically use. The power adapter says 19.7 volts and 3.9 amps so i guess thats 76.83 watts which is pretty close to the max. Has anyone used these things successfully with their laptop?

Well, my Dell has its own adapter for the car, but I do own one of those units as well . . . . I have had it power my laptop, and charge my cell phone at the same time with no issues.

I got an xps from dell, which sucks power like a fridge... and it's always been fine in the car.

your laptop converter is 76.83 watts on the DC side. It's probably closer to 96 watts on the AC side assuming 80% efficiency.

But, your laptop probably doesn't max out your AC/DC adapter and the adapter you bought says it can do 120W surge.
It's a close one.
I use one of those inverters rated at 150 watts for my laptop.

I haven't seen one of those that is rated 150 that plugs into the cigarette lighter. The highest I have seen is 100. Most others want you to hook it up to the car battery it seems.

Yes, I would of prefered an adaptor that works with the laptop rather than this inverter. The people at bestbuy were not helpful at all. Maybe I will stop by the sony store and see if they have that for the vaio.

I've used an inverter with my Macbook with no problems. Not sure which one I got but it was a cheapass one

It should be fine, only thing is don't leave the inverter on for hours and hours and make sure it is well ventilated - they get hot!

i wonder if using this would be better

http://www.bestbuy.ca/catalog/prodde...08&catid=20182

definately will save you some power in the DC -> AC -> DC conversion loss and handy to have on plane rides.

I have this one, work fine.

http://ep.yimg.com/ca/I/yhst-8166938...4_2084_5947743

Overview: The AIMS Power can-size 150 watt power inverter is designed to fit into any cup holder that will hold a standard size soda can. This inverter is designed so it doesn't roll around in your car and fits perfectly in your cup holder so you can charge equipment such as laptops, MP3 players, games, cellular phones, cameras or any electronics that require 120 watts or less

http://www.theinverterstore.com/the-...odel=pwrcup120

I use one similar to the 1st one you posted with my laptop and also with a printer..not a prob at all

I have one in the console of my MKX we use it on long trips to power the laptop. Driving to Mont Tremblant Quebec is about 6 hours and I have used it the whole way there!

I love it

I use a generic DC-DC laptop power supply that allows you to select the output voltage. So long as you're very c-a-r-e-f-u-l in setting this you should be fine.

Converting from DC to AC back to DC is very inefficient, and inefficiency is probably something you would need to be concerned about if you're going to use your laptop for any length of time with your engine off... you might find your car doesn't start. :D

Looking at it another way... if the AC power supply and DC-AC inverter are both 80% efficient, you'll be wasting around a third of your input power in conversion losses (which will mostly be emitted as heat)

You'll be fine, even using an inverter.
Don't leave is plugged in with the engine off for a long period of time.. especially if you have a tiny car battery or if it's really cold, outside.

If you're going to be sitting in traffic jams idling for a long time, pop into neutral every 20 minutes or so and rev the engine up around 1300 rpm for a couple of minutes (same thing if you're just sitting parked somewhere)

I use to use my exes laptop in her car all of the time.. got a $30 inverter that also had an fm transmitter so the sound from the laptop would come out through the car radio.. think it was 100w or so.. only thing it hated was her curling iron.. LoL over here... the little fan in that thing went crazy!!! Lucky it didn't burn it up, because I think curling irons are around 400w

I have a 200W http://www.walmart.com/catalog/produ...440 153379269

We had this one
http://www.walmart.com/catalog/produ...uct_id=5162346
It's rated at only 110w
But it ran the 400w curling iron a couple of times..
I would NOT have wanted to use it for a 400w draw more than once or twice, it got real upset and overheated, but it will run and charge a laptop for hours on end without getting too upset. It'll heat up and the fan will run fast sometimes, but it'll work.. plus it has passthrough so you can still use the cigarette lighter and the fm transmitter so you can hear your laptop through your car radio

EDIT: It even has usb charging ports on it.. Fucking beautiful, this thing is.

this one looks pretty cool

http://www.walmart.com/catalog/produ...ct_id=10746777

200 watts/400 max although with all the talk of loss during conversion it sounds like it would be better to have an adapter cord for the laptop rather than using these inverters.

I thought that looked pretty damned cool when I saw it earlier on there, too.. Only thing is, I will all but stab someone to death for putting anything in my cupholders :winkwink:

I'd much much rather just have an adapter cord
I always thought that they had dc-->ac-->dc inside of them though
I was probably wrong:error

The one I linked to will do the work, just fine, and it's got other useful features!

Since duration has been mentioned . . . I drove from LA to Chicago and back (in a large oval) and had things powered off it the entire way.

I still carry it with me when I travel.

Well I'll be testing it out today. Going on an 8 hour trip. I'm not going to be using it the whole way but I wonder if leaving it plugged in while the laptop is in sleep mode would use much power.

I think that it will still draw quite a little bit if it's charging the battery while it's asleep and plugged in.. which I am sure that it is..

I left mine plugged in for longer than that. No worries.