What size / type Inverter for laptop off 12v DC

[Jinx491]

Hi folks, I have an Alienware M18x I am looking to run off a portable 12v DC supply, I have been looking at inverters from 12v DC to 240v AC but do not know what size / type to go for.

Details on power pack state:
Input:
100v-240v ~4.4A 50-60Hz
Output:
19.5v 16.9A.

Also will it need to be a pure sine wave or will modified sine wave be ok.

Thanks in advance,

Alec

[stroyal]

Don't know exactly, but maybe I can get a conversation going.

First you input watts are what I think you are looking for.
Your power pack, doesn't help the confusion.

If the amps are 4.4 @ 240volts, then they should be 8.8 @ 100.
They can both be 4.4.

The amps multiplied by the volts, will give you the watts.

Volts x Amps = watts
Watts / amps =volts
Watts /volts =amps


If 4.4, is the amps @ 240volts, then the watts are 1056, and an inverter that size or bigger, should work.

If 4.4 is the amps @ 100volts then the watts are only 440.
gota love a ~, in an exact science.

Edit
The output is only 329.5 watts, so the input is most likely 440watts.

Bigger can't hurt, but too small will run hot, at the least. (most likely will fail)

Not sure of your sign wave question, but I'm guessing cycles.
60 times a second in the US, and 50 in most of the rest of the world.

I have always suspected UPSs use a modified wave, because when they loose line power, the voltage goes from 115v to 70v, and the computer stays running.

I can't believe a computer can run on 70volts, so I always assumed it was doing something, my multi-meter, can't measure.

[stroyal]

I think this says, you don't need a pure sine wave, for desktops.

It says full time systems can benefit, but the only reason stated is if they have AC motors.
AC motors will overheat, with a square wave, or a modified one.

No AC motors in a desktop, or a laptop
It also says DC conversion, in the computers power supply works better with a square wave.

Uninterruptible Power System Waveforms - Is A Sine Wave Necessary?

[stroyal]

l always look, for non-computer places to by computer stuff, if possible.

ie. I buy my network supplies, and cat5e/6 cables at Home Depot, for considerably less, than a computer store.

Northern tool, sells inverters.
Power Inverters: Pure + Modified Sinewave Power Inverters | Alternative + Renewable Energy | Northern Tool + Equipment

[electric]

if i read the OP question correctly he/she is going from AC to DC voltage
therefore the OP needs a rectifier not an inverter


Rectifier - Ask Jeeves Encyclopedia

[electric]

i never buy any cables from Best Buy or Future shop
Princess Auto much cheaper, who though a auto place sold computer
gadgets . lol

[paul9]

Using an inverter, then an AC adapter will introduce losses and inefficency. You should look at a car laptop charger, instead. Something along the lines of
Play.com - Buy online at Play.com and read reviews. Free delivery to UK and Europe!

Not neccessarily that one, it was just the first I saw on Google, and Play is a reputable retailer.

Electric, the OP needs more than just a rectifier, it also needs to be a step-up transformer of some type.