Since it charges over Micro-USB, seems like you should be able to recharge with one of those portable "juice packs" like they make for cell phones. That would be very convenient, because you could recharge the Surface hidden away in your bag and not plug into a wall outlet until you get home. If they juice pack is slim, it would easier to carry in a slim bag with the tablet than the blocky, protruding power adapter that comes with the Surface. However, a Surface 3 would require much more power to recharge than any cell phone. How much juice would a Surface 3 need to recharge and do manufacturers make juice packs that would recharge it fully or even add more than 50% of a recharge?