The Lithium-Ion battery has a spec of 207.2 volts and capacity if 3.6 ampere hours. So that makes it a 745.94 watt hour battery. MG2 has an output rating of 53 kW. I'm going to assume the motor is 100% efficient. Dividing, and converting to seconds, that gives the battery 50 seconds of 53kW with 100% efficiency That doesn't seem very long. How many hp does it take to keep a Prius rolling, on a smooth flat and level, say at 40 mph ?