@Kit Eizenga
Hi,
The conversion status could alternatively be listed as “Used Space Only Encrypted” when percentage encrypted reaches 100%, this is because BitLocker has the option of encrypting only used data which will be a lot faster to complete as there is less of the disk to encrypt but can be less secure, or full disk encryption which will encrypt the whole disk regardless of which parts are in use.
Based on my research, the "Used Space Only" will be much more efficient than full encryption and the new added data will be encrypted automatically but the deleted data before the encryption won't be protected.
If this is a new drive, there is no need to change the encryption mode. If you are concerned about the deleted data before the encryption, we should turn off the BitLocker and turn on it again to change the mode.
For the two types of the encryption mode, here is a link for reference:
https://web.archive.org/web/20150906083802/http://technet.microsoft.com/en-us/windows/jj983729.aspx
Hope above information can help you.
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