EDIT 2020/06/05: Pass-over-midnight adjustment added
@echo off
setlocal EnableDelayedExpansion
set "startTime=%time: =0%"
set /P "=Any process here..."
set "endTime=%time: =0%"
rem Get elapsed time:
set "end=!endTime:%time:~8,1%=%%100)*100+1!" & set "start=!startTime:%time:~8,1%=%%100)*100+1!"
set /A "elap=((((10!end:%time:~2,1%=%%100)*60+1!%%100)-((((10!start:%time:~2,1%=%%100)*60+1!%%100)", elap-=(elap>>31)*24*60*60*100"
rem Convert elapsed time to HH:MM:SS:CC format:
set /A "cc=elap%%100+100,elap/=100,ss=elap%%60+100,elap/=60,mm=elap%%60+100,hh=elap/60+100"
echo Start: %startTime%
echo End: %endTime%
echo Elapsed: %hh:~1%%time:~2,1%%mm:~1%%time:~2,1%%ss:~1%%time:~8,1%%cc:~1%