Is it possible to put a function in timed loop using django-background-task
No It's not possible in any case as it will effectively create cyclic import problems in django. Because in tasks you will have to import that function and in the file for that function, you will have to import tasks.
So no whatever strategy you take, you are gonna land into the same problem.
Say i want to execute a function every 5 minutes without using cron job.
What i think of doing is create a django background task which actually calls that function and at the end of that function, i again create that task with schedule = say 60*5.
this effectively puts the function in a time based loop. 
I tried a few iterations, but i am getting import errors. But is it possible to do or not?