Backup Battery

[BQuennell]

Also on the backup battery, I'm curious to if we can use a backup battery charging circuit from last year. It doesnt list any design in the manual and rule R49 lists
When mounted on the ROBOT, the backup battery may be charged from the 12VDC primary battery by using the custom charging circuit available from Innovation First Inc. or any similar charging circuit (note: IFI will provide the design for this circuit on the IFI website, however teams must obtain the parts for this circuit and assemble it themselves). The use of this circuit is strongly encouraged.

With that does that mean teams can design their own circuit as well?