Are "ins", "hrs", "mins" and "secs" the technically correct plural abbreviations for "inches", "hours", "minutes" and "seconds"?

Are "ins", "hrs", "mins" and "secs" the technically correct plural abbreviations for "inches", "hours", "minutes" and "seconds"? I'm hoping that all examples below could possibly be correct.

Examples:

Plural: He finished the race in 4hrs 34mins 9secs.

Singular: His 4hr 34min 9sec finish was unprecedented.

Plural of 'inches': Garry was 5ft 10ins tall.

Singular of 'inches': Garry was a 5ft 10in man.

Solution 1:

The SI unit for time is Seconds (s). Hours (h) and minutes (min) are accepted to be used within the SI even if not standardised. In scientific writing you should probably stick to those abbreviations (note that it's 60 min not 60 mins).

In common usage all your examples should be understandable. As is, for instance, the 5'10" style for feet-inches

Solution 2:

IUPAC (see section 1.3) and NIST sanction that "unit symbols are unaltered in the plural".

UPDATE

In the comments, oerkelens makes the distinction between unit symbols and abbreviations. Unit symbols are attached to a number to define its units, e.g. 5ft 10in, and abbreviations can be used independently, e.g.:

• How many "secs" have we left?

I agree with oerkelens that the above use can be found in colloquial conversations.