According to Official Guinness Records,
The most AA batteries held in the hand is 48, achieved by Silvio Sabba (Italy), in Pioltello, Milan, Italy, on 19 March 2012.
This record was broken on the Guinness World Record Challengers site (Challengers' tag: silvio.sabba): http://challengers.guinnessworldrecords.com/challenges/63-most-aa-batteries-held-in-the-hand
For a complete list of 2012 records, please visit 2012 Guinness Records in Italy.