This is stated in the broadcast of Roscosmos.

“Oleg, this is a very low voltage, you urgently need to return,” said a specialist from the Mission Control Center to Artemyev during the negotiations.

The specialist explained that if the battery is completely discharged, then communication may be lost, RIA Novosti reports.

In this regard, he was recommended to "immediately go into the hatch and dock to the station."

Earlier, Roscosmos cosmonauts Oleg Artemiev and Denis Matveev went into space to work with the ERA manipulator.