Laptop power

OK, so this really belongs on the CHOTA blog....but I suppose it comes also under the general radio and electronics stuff I do...

I have an old(ish) Toshiba Equium A200 laptop, this is alright for general radio use, but the battery is shot, and I cant justify paying the price of a new battery! Now, I really want to be able to use this in the field, or car. Ive tried it on a 12v SLAB, but it wouldnt power at that low a voltage. The specified supply is 19v (although its battery is rated 10.8v???). So ive decided to invest in a 'car charger', like this one 

With any luck, this will solve the problem of running the machine from a 12v DC supply. This will allow me to run WSPR etc mobile (well, parked up!), and especially at the church station. I will have to measure the current taken when running just WSPR on the laptop, to work out what battery capacity I really need for a days working.