The DJI Phantom 4 Battery Charging Hub ;is designed for use with the Phantom 4 Intelligent Flight Battery. When
used with the Phantom 4 Battery Charger (available separately), it can
charge up to three batteries in series.The batteries will be charged in
sequence according to their power levels, starting with the battery that
has the most charge. Storage Mode allows the Charging Hub to maintain a
50% charge, ensuring the voltage stays above the minimum safest level.