Balchack is a multiple of the standard time-measuring unit of the Chodak species, which is the chalkot, just like megasecond is to second for Terran SI units of measurement of time.
The exact value of one chalkot in other units of measurement of time (in seconds for example) can be deduced precisely from the information presented in the mission "Allanor" of TNG video game: A Final Unity.
It is psychologically suspected to be the Chodak equivalent of a century (approx. 3,155,760,000 seconds), however it is not equal to this nominal value.