Right now I'm using a Kmashi 15k mah battery pack to power my picade. You CAN experience some brownouts if you overload the system (like running volume too high or adding other USB things like keyboard etc) but it works great if you want a portable power supply.
I actually have two battery packs so I can power the monitor separately. I haven't had a chance to try it out yet. Just put mine together last night.
Just wanted to let everyone know that it was possible to go portable.