This Profoto LiFe Lithium-ion Battery For Acute B2 600 AirS and AirS/R allows the generator to deliver up to 225 flashes on a 5-hour charge with the standard charger or a 2.5-hour charge with the quick charger. LiFe cells have a higher capacity and weigh less that the lead-acid battery. They also have a longer life thanks to integrated electronics that protect it against deep-discharge and overheating. The battery can be charged separately or inside the Acute B2.