Belt alternator starter
Encyclopedia
Generation I BAS
General Motors introduced a mild hybridMild Hybrid
Mild hybrids are essentially conventional fossil-fuel vehicles equipped with a large electric machine allowing the engine to be turned off whenever the car is coasting, braking, or stopped, yet restart quickly...
system called belt alternator starter (or BAS) in the 2007 Saturn Vue Green Line
Saturn VUE
The Saturn Vue is a compact crossover SUV that was sold by General Motors' Saturn marque, and at one time was Saturn's best-selling model. It was the first vehicle to use the GM Theta platform when it was introduced in 2002. A second generation model was launched in 2007 for the 2008 model as a...
. The BAS system is also used in the Chevrolet Malibu Hybrid and Saturn Aura Green Line
Saturn Aura
The Saturn Aura is a mid-size car produced under the Saturn brand of American automaker General Motors. It debuted as a concept car at the North American International Auto Show in January 2005. The production model of the Aura was shown at the 2006 New York Auto Show in April, with production...
. It operates similarly to other mild hybrids with a "start-stop" system, in that it shuts down the engine as the vehicle comes to a stop and instantly restarts it when the brake pedal is released.
The BAS system is also capable of providing modest levels of power assist during launch/acceleration and similarly modest levels of "blended" regenerative braking during deceleration. Although unable to operate in pure all-electric EV
EV
EV, eV, e. V. may refer to:* Electronvolt, a unit of energy* Eingetragener Verein, a registered voluntary association in Germany* Estonia's official name, Republic of Estonia, in Estonian: Eesti Vabariik*Everett Railroad's reporting mark...
mode, the BAS system provides improvements to both city and highway fuel efficiency
Fuel efficiency
Fuel efficiency is a form of thermal efficiency, meaning the efficiency of a process that converts chemical potential energy contained in a carrier fuel into kinetic energy or work. Overall fuel efficiency may vary per device, which in turn may vary per application, and this spectrum of variance is...
over similar non-hybrid versions. According to the EPA the 2009 Saturn Vue BAS hybrid garners an improvement of 32% city (19>25mpg) and 24% highway (26>32mpg) making the combined economy improvement 27% (22>28mpg) over the base 4cyl FWD version. The system is reasonably simple and inexpensive, making BAS equipped vehicles some of the least expensive hybrids available.
A 36 volt electrical system
42-volt electrical system
In automobiles, a 42-volt electrical system was a proposed electrical power standard in the late 1990s intended to allow more powerful electrically driven accessories, and lighter automobile wiring harnesses...
(operating at 42-45 Volts) is used to operate a permanent magnet motor/generator unit mounted the engine in a similar fashion to a conventional alternator. Then through a high-tension drive belt, the BAS system is capable of starting or assisting the 2.4L Ecotec engine. A conventional 12V starter motor is retained and used whenever the engine is cold as during initial start-up. The air conditioning
Air conditioning
An air conditioner is a home appliance, system, or mechanism designed to dehumidify and extract heat from an area. The cooling is done using a simple refrigeration cycle...
compressor continues to be operated through a belt-driven pulley, but for fuel economy improvement it can be disabled in auto-stop mode if the "ECO" A/C mode has been selected by the operator.
Vehicles with the BAS system use a conventional 4T45-E automatic transmission
Automatic transmission
An automatic transmission is one type of motor vehicle transmission that can automatically change gear ratios as the vehicle moves, freeing the driver from having to shift gears manually...
which has been modified to include a more efficient final-drive ratio and includes an electrically driven pump to provide pressure in auto-stop mode.
One perceived benefit of the BAS technology is that it fits in the same space as a conventional engine. No significant modifications were required to the vehicle chassis to accommodate the BAS system, with the 36V battery pack housed in the trunk or spare tire
Spare tire
A spare tire is an additional tire carried in a motor vehicle as a replacement for one that goes flat, a blowout, or other emergency...
well. This allows the vehicles to be produced on the same assembly line as the non-hybrid versions, producing substantial cost savings and allowing the company to adjust production more easily.
Cobasys
Cobasys
Cobasys LLC supplies nickel metal hydride batteries, battery control systems, and packaged solutions for automotive applications, uninterruptable power supplies, telecommunications applications, and distributed power generation...
which supplies the BAS system's battery pack had to conduct a recall in 2008 apparently due to internal leakage of the battery modules.
Citing supplier issues and slow sales GM has relegated the 2010 model year BAS hybrids (i.e. Malibu hybrid) to "fleet only" status.
Generation II BAS (eAssist)
At the LA Auto ShowLA Auto Show
The LA Auto Show is an annual auto show held at the Los Angeles Convention Center in late November/early December. The LA Auto Show is an OICA sanctioned international exhibition and also endorsed by the Greater Los Angeles New Car Dealers Association...
, on November 15, 2010, General Motors announced that it would be releasing an all-new version of the BAS system available in the 2012 Buick LaCrosse
Buick LaCrosse
The Buick LaCrosse is a mid-size entry-level luxury sedan produced by General Motors. It replaced the Buick Century and Regal in North America beginning in the 2005 model year.-North America:...
. While still a Belted Alternator Starter system, the system is named eAssist and includes a larger more powerful Hitachi-supplied 115 Volt Lithium Ion battery and a 15 kW motor-generator that delivers 79 lb-ft of torque. The new motor is apparently able to contribute more power in assisting the 2.4L engine and able to operate electric-only but only at very low speeds. The eAssist system includes a modified GM 6T40
GM 6T40 transmission
The Hydra-Matic 6T40 and similar 6T45 and 6T30 are transversely-mounted six speed automatic transmissions produced by General Motors. The 6T40 made its debut in the 2008 Chevrolet Malibu, available with the 2.4 litre LE5 Ecotec engine making , and has since also be made available on the...
6-speed automatic FWD transaxle.
Other Belted Alternator Starter Systems
Robert Bosch GmbH is also producing a BAS hybrid system that is being implemented Ford Transit Light Commercial Vehicle, Volkswagen Passat, and Porsche Panamera.Other names
- BSG: Belt-Driven Starter Generator
- BISG or B-ISG: Belt-Driven Integrated Starter Generator or Belt Mounted Integrated Starter Generator
- BSA: Belt-Driven Starter Alternator or Belted Starter Alternator
- eAssist
Vehicles
- 2007-2009 Saturn AuraSaturn AuraThe Saturn Aura is a mid-size car produced under the Saturn brand of American automaker General Motors. It debuted as a concept car at the North American International Auto Show in January 2005. The production model of the Aura was shown at the 2006 New York Auto Show in April, with production...
Green Line - 2007-2009 Saturn VueSaturn VUEThe Saturn Vue is a compact crossover SUV that was sold by General Motors' Saturn marque, and at one time was Saturn's best-selling model. It was the first vehicle to use the GM Theta platform when it was introduced in 2002. A second generation model was launched in 2007 for the 2008 model as a...
Green Line - 2008-2010 Chevrolet MalibuChevrolet MalibuMalibus and all other Chevelles were completely restyled for 1968 with semi-fastback rooflines on two-door hardtops and wheelbases split to on two-door models and 118 for four-door sedans and station wagons. Engine offerings included a new V8 rated at that replaced the V8 that had served as the...
Hybrid - 2012 Buick LaCrosseBuick LaCrosseThe Buick LaCrosse is a mid-size entry-level luxury sedan produced by General Motors. It replaced the Buick Century and Regal in North America beginning in the 2005 model year.-North America:...
w/ eAssist - 2012 Buick RegalBuick RegalThe Buick Regal is a mid-size car introduced by General Motors for the 1973 model year. North American production ended in 2004 and began again in 2011. For the 2011 model year, Buick re-introduced the Regal to the North American market, positioned as an upscale sport sedan...
w/ eAssist - 2013 Chevrolet MalibuChevrolet MalibuMalibus and all other Chevelles were completely restyled for 1968 with semi-fastback rooflines on two-door hardtops and wheelbases split to on two-door models and 118 for four-door sedans and station wagons. Engine offerings included a new V8 rated at that replaced the V8 that had served as the...
w/ eAssist *avail Q1 2012