Toyota Prius (XW20)
Battery
The second generation Toyota Prius makes use of a 201.6-volt NiMH battery composed of 28 modules, where each module is made of six individual 1.2-volt, 6.5 Ah Prismatic NiMH cells. The 7.2-volt modules each contain a charge controller and a relay. The 28 modules are connected in series to produce a total energy storage capacity of 1.310 kWh (via 201.6-volts × 6.5 Ah). The battery control computers keep the state of charge (SOC) between approximately 40 and 80 percent (shallow cycling), where the average SOC hovers around 60 percent, allowing about 400 Wh of useful energy storage to capture energy from regenerative braking and to release it back into the hybrid drive-train through Motor-generator 1 and Motor-generator 2 in the power split device. The shallow cycling enables the hybrid battery to last tens of thousands of cycles, which translates into decades of use and in many cases more than 200,000 miles (320,000 km) of operation. The computer controlled charging and discharging of the battery enhances its cycle life, calendar life, and thermal control performance. Passive battery cooling and heating is accomplished through the metal case of the battery assembly pack, while a forced air cooling system with a blower motor and ducting system enables active cooling of the HV battery.
Toyota Prius (XW20)-4