Interesting question
As per the 3.03.06 p4, how do we come to the conclusion that there is a problem?
I mean that, What if we find the amps too high after 60 secs?: We just wait until the charging cycle ends (battery contactors open). Then we perform the check again: since the batteries have just been charged, amps will (should) be low, now.
What is the meaning of a high amp reading? that the batteries had very low volts and therefore charging current is very high so you have to wait until the batteries are fully recharged?
Maybe we wait until that happens or either an ELEC BAT FAULT is triggered instead ("charging current increases at an abnormal rate"). If it doesn't, we check again to make sure and go on with the preparation...
This check is to be carried out in the first flight of the day, even if the airplane has been energized continuously for hours before you arrive to the deck.