How to keep Time Zones of the data?

How to keep the original Date values of my data. Original tz is "EST" and the command returns "IST"

(dtDH<-dtInFaults[inMode=="DCE",c("inMode","Start_Time","End_Time"),])
   inMode          Start_Time            End_Time
1:  DCE 2021-11-07 19:23:41 2021-11-07 19:27:44
2:  DCE 2021-11-07 23:28:32 2021-11-07 23:33:34
3:  DCE 2021-11-08 03:34:21 2021-11-08 03:38:20
> (lim <- as.POSIXct(c(dtDH[1,Start_Time], dtDH[1,End_Time]),"%d/%m/%Y %H:%M:%S"))
[1] "2021-11-08 02:23:41 IST" "2021-11-08 02:27:44 IST"
> (lim <- as.POSIXct(c(dtDH[2,Start_Time], dtDH[2,End_Time]),"%d/%m/%Y %H:%M:%S"))
[1] "2021-11-08 06:28:32 IST" "2021-11-08 06:33:34 IST"
> (lim <- as.POSIXct(c(dtDH[3,Start_Time], dtDH[3,End_Time]),"%d/%m/%Y %H:%M:%S"))
[1] "2021-11-08 10:34:21 IST" "2021-11-08 10:38:20 IST"