I was thinking of getting a netbook or small laptop for use while traveling. When I looked for DC chargers, most references I found were for using an inverter and the laptop's standard AC charger. I suppose that this would work, but inverters tend to be heavy and are reputed to add substantial electrical load.

I have seen a couple of direct 12 volt DC chargers (such as the PWR+ sold by Amazon) that are much smaller, lighter and claim to use less power. Any electrical wizards know if these devices are any good?

I have always heard that DC does not lend itself to readily changing voltage so I am curious what the direct DC chargers are doing to step up or down the voltage.