E-mails being sent or nodes being saved by batch api breaking on a regular schedule just during cron runs
If you are having weird problems in Batch API processes, such as the base URL for notification e-mails being replaced with something less-than-useful like /var/www/drupal, the culprit may be (somehow) cron.php being called by a command line script (rather than curl or something going to cron.php over the internet).
Calling Drush cron can also fail. Perhaps adding this optional flag (l or uri, they are the same) would help, though its purpose is just to pick the right site from a multisite:
-l http://example.com, --uri=http://example.com
Added the base url
$base_url in settings.php, hope it will work.