Charging Hub. Features: The Tello Battery Charging Hub is designed for use with Tello Flight Batteries. It can acco mmodate up to three Tello Flight Batteries at the same time. The Tello Battery Charging Hub charges batteries in sequence according to their voltage levels, from highest to lowest. The Battery Charging Hub does not include a charger. Compatible Battery Model: GB1-1100mAh-3.8V. Operating Temperature Range: 5° to 45°C. Input Voltage: 5 V. Weight: 29g. Charging Time (3 batteries): Approx. 2 hours. Compatibility: Tello Flight Battery.