Governor limits for batch Apex:
- Only one batch Apex job’s start method can run at a run time.
- Up to 5 queued or active batch jobs are allowed for the apex.
- The maximum number of batch apex method executions per a 24 hour period is 2,50,000.
- The batch apex start method can have up to 15 query cursors open at a time per user.
- A maximum 0f 50 million records can be returned in the Database.QueryLocator object.
- The Start, Execute and Finish method can implement up to 10 callouts each.