without getting into the embarrassing nitty-gritty of why I lose certain versions of my Excel work, overwriting files, etc., is it possible for AutoSave to:

1) While I am working on Excel, using the main drive of my puter (:C), is it possible for AutoSave to save every 15 minutes ONLY to a secondary Drive:D (I don't want AutoSave on the version I am working on in Drive:C, I want to save it manually only at the end of my session)

2) Additionally, it would help a lot if the AutoSave version every 15 minutes to Drive:D was automatically saved under an appended file name.

Eaxmple:

DesignWkBk 03.19.14 was automatically saved as DesignWkBk 03.19.14_1 in the first 30 minutes, then DesignWkBk 03.19.14_2 in the following 30 minutes etc.

This would result in large number of files saved in the secondary drive, but is a huge 7200 rpm disk drive, while my primary drive :C is a very small SSD drive.

Or would you recommend getting software or an external drive with proprietary back-up software (if any exists)?

Finally, I am not interested in online backup or cloud computing methods. I have attempted both and they significantly slow down my computer, and my residential ISP provider (TV and internet by cable box) is prone to interruption of service, which I absolutely can't tolerate when I am doing billable work (I work at home intensely for 5 hrs doing billable and 3 hrs dabbling here on Eng-Tips and improving my Excel each day)