I've been looking for something in which I can take with on field tests that require electronic equipment. The problem is powering some of this equipment (such as audio interfaces that are not bus-powered) What are my options in terms of finding a mobile battery pack with an AC Plug? Something capable of at least a few hours use with minimal equipment attached. If it can keep a laptop charged for half a day than I'd be satisfied. More importantly is being able to keep an audio interface powered in the meantime, as expanded usb interfaces are far and few when they need to have at least 4 available mic in's and still manage being bus-powered... which I don't believe is possible just yet I suppose if I had to use a power inverter with a car battery - it'd be fine, but I'd like to know what my other options are Any ideas?