Lots of questions here.
Here goes.
1. No way am I posting "EXPORT CONTROLLED-BOEING PROPRIETARY-Copyright unpublished work. IE SCHEMATICS.
Sorry but I have a mortgage and mouths to feed.
I will however enter into discussion to try to increase knowledge and understanding, especially mine.
2. Referring to my own hand written notes, the battery can be recharged on the a/c in less than 90 mins.
3. The APU can be started using power from either: APU Hot Battery Bus, AC Bus L1 or AC Bus R2. Depending on which busses are powered, which in turn will depend on what power sources you have available. EG Engine Gen, Ext Pwr (Two Fwd One Aft).
4. Brakes systems are powered from Hot Battery Bus when no normal AC Bus is available. IE. Towing without APU. In an emergency though, only three of four, brake systems are powered- from the Backup Bus, which of course, can receive power from the RAT Gen.
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