The old 13inches macbook has been laying for a while. Broken screen, power and logic board water damaged. I would like to use the battery (which is intact) as a 5.5V battery pack with two outputs (1Amp and 2.1Amp). After a little aluminium cutting I should have enough space to fit two 2.5 hdd and one SD card reader. The macbook would be closed forever.
The aluminium shell has:
1 magsafe port (used to charge the battery)
2 usb ports (used as power output)
1 SD Card Slot (fit SD Card Reader)
1 Thunderbold (used to connect the 2 hdds and the Card Reader)
1 3.5 jack audio port (left empty, any idea is welcome)

I am looking for someone who has been playing around with apple magsafe chargers. The main problem I have for the moment is to design a circuit to manage the battery (charge and discharge). And to find a pinout for the battery.