Replace HDD with Battery I had serval problems with the SATA cable for the hard disk on my MacBook Pro 13" mid 2009.

Buying a new cable from apple was too expensive for that old MacBook, so I kicked out the SuperDrive and put my disk in there.

Now there is quite a lot empty space in my MacBook and I wonder if it would be possible to put a bigger battery in there.

Considering that the old battery is 8 years old and there is more space now it should be possible almost double the battery capacity.

Now I wonder if there is any way to get such a battery?
Buying a new cable from apple was too expensive for that old MacBook,
  so I kicked out the SuperDrive and put my disk in there.


Doing a quick check, this is currently selling for $14 including shipping.  While I'm not against adding a second hard drive, this fix is very much economically feasible to keep your drive in it's default location.


  Considering that the old battery is 8 years old and there is more
  space now it should be possible almost double the battery capacity.
  
  Now I wonder if there is any way to get such a battery?


Unless you plan on building your own battery pack, this is simply not an option.  Your best bet is to replace the cable and battery and simply be done with it.