SD memory for Time Machine?
While we don't know how large your SD card is, it is likely not big enough to support a backup. The information and link below provides details on how much space to plan for.



Answer by sameetandpotatoes just here



You probably want to check out this website for the most information, but here is the answer to your question, quoted from the website above:

1. How big a drive do I need for Time Machine?


  A general "rule of thumb" is, to keep a reasonable "depth" of backups,
  Time Machine needs 2 to 4 times as much space as the data it's
  backing-up (not necessarily the entire size of your internal HD).  Be
  sure to add the size of the data on any other drives/partitions you
  want to back up.