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Is it possible to power a laptop w/ the 'cigarette lighter'?

Posted: Tue May 19, 2009 12:35 am
by crudman
I'm wondering if i can power my full sized laptop with the cigarette lighter port.

The cover on the 'lighter' says 12V 120W... so it must be 10Amps

My laptop AC->DC power adaptor is rated at 20V, 90W and 4.5Amps

so I was thinking of increasing the Volts somehow (adding resistors or something) but short of another battery I don't know if its gonna work. I dont fancy installing a 2nd either...

V=IR
P=IV
those 2 equations only go so far...

only ever did electronics up until yr10 haha

Posted: Tue May 19, 2009 1:07 am
by Dummer
Resistors drop voltage. I think you can get IC packages that will increase DC to DC voltages. Unfortunately increasing a DC voltage isn't easy to do in your own circuit. Then you have to have power conditioning and do you know if the charger is supposed to have circuitry to determine the current to push into the battery?? My advice go to dick smith and buy a 12V laptop charger that has the right output voltage and plug for your laptop!!

Posted: Tue May 19, 2009 3:42 am
by Speedie
Just buy the car adaptor for your laptop from WOW or JB hifi

Posted: Tue May 19, 2009 4:40 pm
by slickthug
better idea.
get a power inverter. changes ac to dc via some sine wave bulltish.

makes the cig slot to a power point. i think they can go up to 200 watts. any bigger you have to connect directly to the battery.
they also have a fail safe. if you use too much battery it will cut power to you laptop or small device.

only issue i have its too big and theres a fan inside that makes a bit of noise but im sure you doofdoof can cancel that out.

many advantages though. less than half the price of laptop adaptor. can support all laptops. charge your mobiles and cameras. some even come with usb charger.

heres where i got mine from
http://www.shoppingsquare.com.au/search ... egodQDudEg

Posted: Tue May 19, 2009 4:46 pm
by slickthug
dont forgot once you have you laptop in your car you can park at you local maccas and get free wifi.

if you feel a bit of a tite ass just go drive through and by a softserve cone. haha.

dont even have to get off your ass

Posted: Tue May 19, 2009 5:21 pm
by SIR-VRX
You can get 12V to 230V inverters that are the same size as a coffee travel mug now (designed to fit into cupholders) or even ones not much bigger than a GPS power plug.

They are enough to power laptops and small things like other chargers. Wouldn't hook a TV up to them whilst camping though haha

They aren't too dear either

http://www.jaycar.com.au/productView.as ... rm=KEYWORD

http://www.jaycar.com.au/productView.as ... rm=KEYWORD

Posted: Tue May 19, 2009 6:33 pm
by Dummer
The only thing with those SIR-VRX is that the guys at Jaycar couldn't gaurantee how smooth the chopped sine wave will be and whether or not switch mode power supplies would get upset by them (I'd imagine laptop chargers are now switchmode units)...

So if you're going to try them you have to make sure you get a gaurantee from the blokes that you can return it if it won't work :lol:

But still going DC to AC to DC is kinda pretty inefficienient, better off just getting a 12VDC to 20VDC adaptor...

Posted: Tue May 19, 2009 6:38 pm
by SIR-VRX
Yes I agree with you Ryan, but sometime you can't just buy a generic adapter. Apple Macbook anyone? HAHAHA

Posted: Tue May 19, 2009 6:43 pm
by Dummer
SIR-VRX wrote:Yes I agree with you Ryan, but sometime you can't just buy a generic adapter. Apple Macbook anyone? HAHAHA


Well only idiots buy macbooks in the first place :P

Posted: Tue May 19, 2009 7:05 pm
by SIR-VRX
Ryan_C wrote:Well only idiots buy macbooks in the first place :P

I didn't :P :P

the missus did but

Posted: Wed May 20, 2009 1:16 am
by slickthug
Ryan_C wrote:
SIR-VRX wrote:Yes I agree with you Ryan, but sometime you can't just buy a generic adapter. Apple Macbook anyone? HAHAHA


Well only idiots buy macbooks in the first place :P


hhaha lol

Posted: Wed May 20, 2009 5:55 am
by jamez707
an inverter can be multi purpose . i have been looking into the idea for a wile

Posted: Thu Sep 10, 2009 12:41 pm
by tmr_colt
Yeah like the guys said, I'd go with an inverter for the added capability.

Posted: Thu Sep 10, 2009 10:45 pm
by SIR-VRX
Oh and an update...

The Apple Airplane Power Adapter works in the car fine, even though it says it will not work in the car.

The engine needs to be running, and it only powers the Macbook, not charge the battery.

Posted: Thu Sep 10, 2009 11:14 pm
by Speedie
Belkin makes one.