Power Extension Dock for Mark 2

Please note:
The charging power is designed to first go to the batteries, and then the batteries feed the power to the Mark 2 AC.
The max charging current accepted by each Mark 2 Battery is about 5.5A, and the max current consumed by the Mark 2 AC is about 10A. So if two batteries are connected powering the Mark 2 AC whilst charging by the power adapter, the Mark 2 AC will always have sufficient power, and the batteries will be fully charged eventually.
However, if only one battery is connected powering the Mark 2 AC whilst charging by the power adapter, the battery will be drained.
For example, if the battery is fully charged, it can last 5 hours powering the Mark 2 AC without charging, but now with the extension dock charging by the power adapter, it can last around 10 hours.