The LS 600h L is defined as a "full hybrid," capable of operating in electric-only mode or with a combination of the gas engine and electric motor. In contrast, other hybrid technologies require constant gas operation and are not capable of running only on electric power alone. Lexus hybrid technology allows electric-mode-only operation at low speeds or stop-and-go driving conditions, reducing fuel consumption and noise.
The hybrid system in the LS 600h L uses a 288-volt DC Nickel Metal Hydride (Ni-MH) compact battery pack installed behind the rear seat. The trunk also contains a 12-volt auxiliary battery that powers the audio, navigation, and other systems. The battery’s power is directed through a "boost converter" that efficiently raises voltage to a maximum 650V DC. An inverter changes this to AC, providing it elevated power to a 165-kW electric motor that turns at a rate of as much as 10,240 rpm. Lexus engineers devised a higher output inverter that both increases output by 10 percent and makes it compact in size and weight for easy mounting in the engine compartment.
The LS 600h L’s powertrain uses two motor generators: MG1 and MG2. Each performs specific functions and can operate as either a motor or a generator, although MG1 is used as a starter motor and provides no motive force. The engine-driven generator, MG1, can charge the battery pack or provide additional power to the drive motor, MG2, as needed.
Full-Time All-Wheel Drive
The vast power of the LS 600h L is distributed by a newly developed full-time AWD system that delivers superior handling and traction control. This state-of-the-art system adapts to almost any road surface to help provide excellent vehicle stability during acceleration, high-speed driving and cornering while also delivering the natural handling feel of a rear-wheel-drive vehicle.
The outstanding performance of the AWD system is accomplished through a new transfer case that is ultra quiet, compact and equipped with a unique Torsen® limited-slip differential (LSD) that is 30 percent lighter in size and weight than previous Torsen® systems. To maximize the AWD system’s performance, the LSD features a rear biased torque distribution of 40:60 under normal straight-line driving. The LSD automatically and continually adjusts power distribution between the front and rear wheels according to changing speed and road conditions.
The micron-polished finish of the gears in the transfer case renders remarkably low noise levels. Placement of the LSD inside the transfer case further reduces noise and helps eliminate the raised-floor tunnel, providing enhanced interior comfort.
Extraordinary Hybrid Transmission
The LS 600h L features a dual-stage electronically controlled continuously variable transmission. The combination of a V8 5.0-liter AWD system and hybrid transmission results in impressive power and seamless acceleration.
The dual-stage electronically controlled continuously variable transmission includes eight-speed sequential braking. The sequential braking mode is activated when the shift lever is in the "S" mode, allowing eight different stages of response. When up-shifting, engine speed is controlled by the selected range, offering an exhilarating boost in acceleration during each of the eight shift stages. When downshifting, brake-force increases allowing for an equally exciting deceleration.
Power is controlled by a three-mode hybrid switch to allow the driver the most effective use of torque output. The driver can select "hybrid" (normal), "power," or "snow" options. The "hybrid" mode provides the smoothest operation and is ideal for city or suburban driving; "power" sharpens accelerator pedal response and "snow" mode softens accelerator pedal response, making it easier to accelerate on slippery road surfaces.
For the ultimate in quiet driving and low emissions the LS 600h L features an EV drive mode. By pushing an EV switch, power reverts to full electric mode for short-distance, slow driving situations such as residential areas or parking garages.
Optimum Fuel Saving Technology
The LS 600h L is equipped with a power-steering system and air-conditioning compressor that are electrically powered to reduce parasitic losses to the engine, thereby helping improve fuel consumption. This is necessary because, as a fuel-saving benefit of the hybrid system, the gas engine often shuts down, particularly when the vehicle is stopped or driven slowly in traffic. Additionally, demand on the air conditioner is reduced through the use of ultraviolet and infrared ray-reducing tinted glass on all windows.
A regenerative braking system further boosts efficiency. When the vehicle is coasting or the brakes are applied, the electric motors function as generators, capturing kinetic energy that would normally be lost as heat through the brakes and transforming it into useable electricity to recharge the batteries.