Reasonable discharge current is 1.2 amps to 12 amps. Then the reasonable motor power is:
48*1.2=57.6 watts
Lithium. batteries are common Calculated based on 4 hours of discharge, the discharge current is 3 amps to 12 amps.
The power of the equipped motor is: 48*3=144 watts
Medium electric bike, 48 V-12 Ah lead acid batteries are generally equipped with 250 to 300 watt motors.