The real problem with most inverters is not how they are rated, but the
way they are feed power. A 300 watt inverter needs 30 amps minimum. If
you need to reach a 400 watt peak, than you need well over 40 amps. The
hard part to understand is how a 300 watt inverter can be expected to
work with a cigarette lighter plug. In the VW, things are really bad as
the lighter socket is connected with a 20 gauge more suitable for 8 amps
at best. The Radio Shack 300 watt inverter has no problem running a
laptop and charging it's battery as long as the wiring and the cigarette
lighter socket has been upgraded or the unit is wired directly. Larger
inverters will work even worse if the wiring is not adequate.

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf
Of Greg Potts
Sent: Saturday, December 03, 2005 12:38 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Inverter at Radio Shack

Hi Joy,

Have you looked at high-end laptops recently?  Extra-bright 17"
monitors are common. DVD-burners are standard equipmment, and
powerful speakers to go with them. They throw off a ton of heat, and
to do that they draw a lot of watts. That means that they're built
with large-capacity batteries, and if you want to RUN the laptop and
charge it at the same time you're drawing twice as much power.

And as I mentioned in an earlier post, the ratings on inverters
recently has little or nothing to do with what they actually produce.
True output is more like a third of rated output.

If someone wants to try to run and charge an "executive class" laptop
I wouldn't recommend purchassing anything less than a 300W  rated
inverter.

Happy trails,

Greg Potts
Toronto, Ontario, Canada

1973/74/79 Westfakia Conversion **Bob the Tomato**  LY3H
1977 Sunroof Automatic L63H/L90D
http://www.pottsfamily.ca/westfakia
http://www.busesofthecorn.com

On 2-Dec-05, at 9:31 PM, Joy Hecht wrote:

> I'm baffled as to why folks need these huge inverters for laptops!