How to calculate elasped time in excel when date and time are in the same cell?

I have series of data in the below format in excel. I want to calculate the elapsed time. I have tried multiple different way but nothing seems to be working.

Format: MM/DD/YYYY hh:mm:ss

Column: C4 - C2500

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Formulas I have tried:

1. Flash entery

2. Separating time into a different column (column D) and calculating batch hours ( column E) with this formula =(D4 - $D$4)*24

(Note: problem with 2 option is, after 12 hours period the batch hour goes to negative instead of getting added continuously. I did check the column format for column D and it was set 'hh:mm:ss')

Please help, I need to get this sorted soon 😭

Thank you