It depends on the capacity of the battery. The amount of charge of the battery is related to the capacity of the battery, the problem is not explained, those parameters you said are only the charger.
Now it can only be assumed that the 48 volt \/12 amp hour battery calculation: 48 volt voltage, if discharged with 12 amp current, power is 576 watts, can be discharged for one hour, 0.576 KWH, that is, 0.576 degrees of electricity. The efficiency of the charger is generally 70%, so the battery must consume 0.82 KWH of electricity from no power to full.