The problem seems to be that even with a perfectly clean slate, no services running, the system set up in their own RAID0 SSD pool, the HDD’s, even with 0 bytes of data on them, are being pinged for access at least once a minute.
if it’s for drive health stats, and the device runs linux, hd-idle could help. it only counts actual block device (so, storage) access as activity
not really. not all drives spin down by themselves, by default. and even if they do, it’ll happen relatively long after reads and writes, a the while it’ll consume power.