Unexpected growth of sql log file in sql 2008

The log file size grows and takes all free space sometimes.  Sometimes it works OK. Following advice may help you to handle the situation

I may be mistaken, but I seem to remember a problem with a previous version of SQL doing this when some other process was interfering with the database files, like a system backup, antivirus scan, system updates or a fragment. When the process interferes with the SQL directory, the log files grew out of control until the hard drive filled up.  If you are running something like this, be sure to exclude your database directories
from it. If you have a different server handling a function like this, exclude the db directories or server all together.

You could put these database In full recovery and set transaction log backups or set up a job that runs DBCC Shrink file. and schedule it to run prior to mid-night. But you should read through the error log and event logs to determine the cause of the problem.