MD-1000I / MD-2000I / MD-3000I Explanation of USB Function
When the USP output and power input sockets are in connected states,
they are capable of transmitting power.
Even if disconnected, dangerous electrical charges may be present in-
side the unit that could discharge hazardous high voltage at the connec-
tions.
As soon as the unit is connected to a source of power, the charger becomes
active. That means without turning the UPS on, the battery charges.
MD Series 30