Photo Tour of Hybrid Batteries

The nickel metal hydride battery used in Highlander Hybrid—and the Lexus RX 400h—is packaged in a newly developed metal battery casing. The 240 cells can deliver high voltage of 288 volts—but the motor-generators units can operate on variable voltage anywhere from 280 volts to 650 volts. The battery pack supplies 288 volts, but the boost converter, a part of the inverter above the transaxle, changes this to 500 volts. This battery pack provides 40 percent more power than the Prius battery, despite being 18 percent smaller.

Each of the modules has its own monitoring and cooling control system. The cooling performance reduces efficiency losses due to excessive heat, ensuring that the battery can supply required electric power to the motors at all times. The battery-monitoring unit manages discharge and recharging by the generator and motors to keep the charge level constant while the car is running. The battery pack is stowed under the rear seats.

(Photo courtesy of the Automotive Career Development Center.)