1.2 kilowatts. The power of the charger is 1.2 kW, the power is equal to the rated voltage times the rated current, the rated current of the charger is 20 amps, the rated voltage is 60 volts. That is, P=UI=60Vx20A=1200w=1.2KW. If you want to be fully charged within 2 hours, the charging current C0.5 = 10A, at this time the power = 10A * 60V = 600W.
When the 60V20AH battery is charged, the maximum voltage of the charger is 74V, the maximum current is 3A, and the charger power is 222W. The average charging voltage is 64.5V, and the charging amount is 21AH, that is, when the battery is fully discharged, a charge requires 64.5*21=1.35 degrees, and it is basically fully charged for 6 hours.