Really Remapping Bad Blocks on disk

I have a SATA drive which has a total of 8 bad blocks identified by the badblocks program. Supposedly the drive firmware should be able to remap them and substitute spares. I've run badblocks in -n mode to rewrite the partition in question, and run e2fsck multiple times. Nothing changes, always the same 8 bad blocks. When I run smartctl it shows the Reallocated_Sector_Ct at 0. How can I get the firmware to actually remap the 8 bad blocks?