Battery diod
Now after the completion of the 787 training and going thru the synopticts it's clear that the earlier mentioned aft ( Apu) battery does not ave a diod. Simply because it does not need one - the fwd ( main) battery has it due to its connected to the main 28v f/o and capt instrument bus - basically everything in cockpit primary or secondary are 28 v dc and are normally fed thru generators via rectifiers . So the potential backloading to the battery is eminent ,so therefore it's fitted a diod to prevent that , then the only source to charge the battery will be thru the charger. However the aft battery ( Apu) is just about only used for the Apu start and will never ever feed into the normal 28 v system ( not connected to that) and the only source into the battery is via the charger so for that specific battery it's not needed a diod . The aft battery is used for Apu start and for some external lighting if aircraft is towed with no power and tow switch selected on.
Just some small info - I could post synopticts but I don't know how to . So whatever happened must have been something else than back power anyway .
Last edited by wings1011; 9th Jan 2013 at 05:23.