Airbus says in ECAM logic:
A
BAT 1 (2) FAULT
STATUS
FUEL CONSUPTION INCRSD
FMS PRED UNRELIABLE
displayed under conditions:
IF BAT 1 FAULT AND ELEC DC ESS BUS NO
VOLTAGE AND ONE SERVO AILERON CONTROLLED
BY ELAC 2 IS INOPERATIVE
OR
IF BAT 2 FAULT AND ELEC DC BUS 2 NO VOLTAGE AND
ONE SERVO AILERON CONTROLLED BY ELAC 2
IS INOPERATIVE.