Question about charging the battery. As far as I have found out, the battery can be charged via the USB cable on the computer. If I'm on the road and don't have the computer with me, is there a power supply unit that replaces the computer's function? And is one of these included in the delivery? If not, what exactly do I have to buy? At least that's what it says in the instructions for use, because third-party power adapters, like those for mobile phones, are not supposed to work.