Done a bit more checking and this only applies to the newer sharklet fitted A320s not to the ordinary ones or A319s.
For ELEC BAT 1(2) FAULT there are no FC actions but the bat contactor opens automatically. If, however, you manually switch off the batt then the extra line about extra fuel consumption does not appear.
In our aircraft TR1 powers DC1, DC BAT BUS and DC ESS, TR2 powers DC2.
Eng A/I VLV 1 is powered from DC1 and VLV 2 from DC2 so it would appear that is not the source of extra consumption as they will still be powered closed even if Bat 1 (2) is disconnected.
I have scoured the electrical supply sections of FCOM and cannot find anything apart from one EIU and one FADEC channel powered by Hot bus 1 or 2. That doesn't mean there is nothing else it is just we are not worthy of the information.
I will try to get an answer from one of our exceedingly helpful engineers but our paths will have to cross to do that so standby.