The AC A-text indicates the battle of Baddon occurred 63 years after Pope Leo’s dating of Easter which occurred in the year 455. This points to a date for Baddon of 518.
The AC B-text describes the occurrence of an eclipse thus:
Anus dies tenebrosa sicut nox.
This is likely to be that which occurred on 23 December 447 and would have been visible over Britain. The document shows Baddon as occurring 71 years later. This too indicates Baddon took place in the year 518.
Further confirmation of this date is given by the ASC and DE as can be seen in the post entitled The Adventus Saxonum.