Originally Posted By: Stretch
I think I might be tempted to take a good car battery, on its own, and see how long it'll run the blanket before it dies. That would at least give an idea of what to expect.


You could, but I'm not sure that's a good idea. As I understand it, a standard car battery can suffer permanent damage, or have its service life reduced, by a severe discharge. Most inverters cut out at around 10.6 volts DC to prevent this.