I want to use my Sony Vaio z505r in my car with an external power source. Comp USA is trying to sell me a $200 car power adaptor. Is there a cheaper solution? How many volts do laptops usually require? Is an adaptor even necessary or can I run it directly off the car battery using the laptop's AC adaptor?

 

Go to WalMart and purchase a $39.00 DC to AC inverter. It plugs into the cigarette lighter/accessory plug and converts the 12 volt dc into 120 ac. Plug your Vaio's AC power cord into the inverter. You can use the inverter with any ac power cord as long as the draw is less than the rated output of the inverter (No more specialty car cords for cell phones, DVD players, laptops, etc.)
You can send me the $160 + I just saved you.

 

Most laptops use around 18 volts, and have special circuitry for charge control of their internal LiI battery in the power input circuit. Jeff48's solution is the best one to use. Try to run a power lead (+ve and -ve) directly from the battery (put an inline fuse on the +ve line at the battery). This will ensure you get the cleanest power you can.
I ran one of these power lines in my car a few years ago and run my radar detector, amateur radio, etc. off it with no noise or other problems. I used #12 cable, but for just a laptop, you could use #14.
I also put a relay in series with it. The relay is turned on by the acc. line in the car, so it is only powered when the car is running, or the key is in the acc. position. It is off when the car is started.

 

Hope this helps...
http://www.targus.com/us/accessories_power.asp

Look for the auto/air adaptor...there is a link in there to look which power tip available for Z505R, i think it is #58.

So buy the auto/air adaptor and the #58 power tip.

Hmm..looks like this includes the power tip you need...
http://www.targus.com/us/product_details.asp?sku=PA379U

 

I think bestbuy also sells an inverter designed for laptop use with built in surge supression and voltage regulation...
http://www.bestbuy.com/site/olspage....oryId=cat08005

 

Thanks a lot guys.

 

bed bath and beyond has a $19.00 70 watt inverter perfect for a laptop...

 

thats the one i use.... i would have gotten a cheaper one but i had a giftcard for a few hundred that was never used so i went on a shopping spree at best buy.... it think mine was $89 at the time....

 

Many of the older laptops (like the old NEC that I use) run off of 14.5 volts.. which is pretty close to 13.8 volts.. I just run a fused wire from my battery.. Might want to check the output listed on the 120V power adapter you have.