Windows 7 Backup takes 800GB? Manage Windows Backup Disk Space

Based on your screenshots, these appear to be multiple backups. Unfortunately, Windows Backup is not performing an Link Removed - Invalid URL but will always perform full backups. This is why you have 2 full backups taking up 800GB. A system image is also being built, which is a very good thing, but will require additional space. Windows Backup gives you a relatively easy way to do backups, but does not have much of an enhanced feature set. For a more robust type of backup, you can do one of two things. Either increase your storage media so that you don't have to delete old backups as often, or purchase a commercial backup application like Paragon Backup & Restore or Acronis True Image.

I hate to have to give you this type of advice, but it is merely the truth. Windows Backup has many limitations. In one of my video tutorials, I explain how to do a Link Removed. This is a fool-proof way of maintaining a very, very accurate backup of your system. Incremental backups can also be made based off the original.