Probablity you've already checked this but there are a various reasons that can limit the daily output on Android devices. For example:

1. By default, the min. Battery level setting is 100% which means BOINC will only start when your phone is fully charged. Reducing the percentage below 100% will ensure BOINC starts before charging is completed.
2. While running BOINC, your phone might get too warm and BOINC will stop the tasks temporarily until the phone is cooler again. Reducing the number of cores might avoid this from happening and providing a higher output.
3. The RAM utilisation % is set too low causing BOINC to limit the number of work-units it will actually run in parallel. Increasing the RAM utilisation % avoids tasks being stopped.