Camera's battery

Is it legal to change our 7.2 battery to our own?

<R68> The 7.2V Robot Control backup battery must be connected to the Controller as described in the Controller’s manual. The 7.2v battery should be charged to at least 7.0v before entering a match. As a replacement for the FIRST supplied battery, any other 7.2V NiCad battery pack may be used.