How can you set onedrive to backup to an SD card, not the C drive?

[WPCentral Question]

I need files on my onedrive for class and I don't have enough space on my surface. I used to have a 128 GB SD card set up back on windows 8.1, but 10 will not let me backup to the card. I tried creating a folder in the C drive and linked it to the SD card in Computer Management, but OneDrive thinks it is still the C drive and says I don't have enough space.

Any ideas?