If the in claus contains 100 parameters the ORA throws an: ORA-01722: invalid number. According to the docs the limit should be 1000 but maybe its the version I was working with 10.2.0.5. Strange thing is that the same query works in SQLDeveloper - but reducing the number of params below 100 fixes the problem.

In any case the default query batch size default can now be set using setQueryBatchSize