I'm away from a power source for the MBA. FruitJuice app wants me to complete the Maintenance Cycle by charging the battery as it's dropped to 20%. Fortunately I have my Lenmar Undead (seriously, that's it's name) topup battery/inverter with me. It outputs 240 VAC into the standard 45 watt Apple charger and a single charge can take the MBA to 100% charged from as low as 4%.