pdooley wrote:
> Most laptops run on more than 12V.

Yep.  The original poster has a Dell Inspiron, which is not listed in
the compatibility list of the "Universal" adapter.  In fact, if the
adapter isn't made to OEM specs, even if it's compatible in voltage and
wattage, it will only power the laptop but not charge the battery.  Dell
Inspirons are proprietary in that way.

I have a Dell Inspiron 8600 which uses 19.5 volts, 4.62 amps, and
requires a unit that is rated for 90 watts.

eBay has units that work with mine for around $24.00 shipped.  In fact,
here's one for $23.29 with free shipping:

http://cgi.ebay.com/Auto-DC-Power-Adapter-for-Dell-Inspiron-8600-9200-9300_W0QQitemZ220309487898QQihZ012QQcategoryZ31512QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

I've never bought from this vendor and there are others as well.

Mike