Lithium-Ion Battery for B1 and B1X AirTTL Flash Heads from Profoto will give you up to 325 full-power flashes and thousands of minimum power flashes on a 2.5-hour charge from the 2.8A multi-voltage charger. The 4.5A quick charger shortens that time to 1.5 hours. Fuel-gauge-type LEDs on the battery and both the optional chargers allow you to monitor the charging progress.