Check the Brunton website for these things, and you'll see that they claim the 7.5 or 15 can charge a laptop by itself. However, the rolls should act like any other battery, in that you can increase voltage by connecting them in series, or amperage by connecting them in parallel - i.e. two of the 3.4s should yield 11 volts DC at .5 amps or 1 amp at 5.5 VDC. You need to look at your power adapter and do the math to figure out what you'd need. If you're going to try to connect two $200 rolls together, you should really do some research into circuits first, if you don't already know what you are doing. Keep in mind, as these actually AREN'T any other battery, the standard disclaimer of "SHOULD" doesn't mean that it will. Tinker at your own risk and don't blame me if you loose your eyebrows and your solar roll. So what ARE you doing with a laptop on the trail?

What the hell are you doing with a laptop on the trail?