General Motors introduced a mild hybrid system called belt alternator starter (or BAS) in the 2007 Saturn Vue Green Line and Saturn Aura Green Line. It operates similarly to the "start-stop" system used in the Chevrolet Silverado Hybrid in that it shuts down the engine as the vehicle comes to a stop and instantly restarts it when the brake pedal is released.^[1] A 36 volt electrical system is used to operate a motor/generator unit that is capable of starting the 2.4L Ecotec engine in less than 500 ms, making the autostart system essentially transparent to the driver. The air conditioning continues to be operated through a belt-driven pulley, but is disabled in auto-stop mode, providing the "eco" A/C mode is selected.

The BAS system is capable of providing modest power assist during launch and acceleration. Although unable to operate in pure EV mode, the BAS system provides about 15-20% fuel efficiency gain in the city.^{[citation needed]} The system is reasonably simple and inexpensive, making BAS equipped vehicles the least expensive hybrids available.^[2]

One major benefit of the BAS technology is that it fits in the same space as a conventional engine. No modifications were required to the Vue's chassis to accommodate the BAS system, with the battery pack housed in the spare tire well. This allows the Vue Green Line to be produced on the same assembly line as the normal Vue, producing substantial cost savings and allowing the company to adjust production more easily.

The BAS system uses a conventional 4T45-E automatic transmission, although it has been modified to include a more efficient final-drive ratio and includes an electrically-driven pump to provide pressure in auto-stop mode.

This system has already found its way to two other GM models, the 2007 Saturn Aura and the 2008 Chevrolet Malibu. In March 2008 General Motors announced their intention to produce a more advanced "2nd Generation" BAS hybrid system that includes a Lithium Ion battery and a more powerful and efficient motor generator unit.^[3]

Cobasys which supplies the battery had to conduct a recall for leaks in 2008.^[4] Later due to slow sales, GM has relegated the 2010 model year BAS hybrids to "fleet only" status^[5]

Contents 1 Other Names 2 Vehicles 3 See also 4 References

[edit] 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

[edit] Vehicles

• 2007-2009 Saturn Aura Green Line
• 2007-2009 Saturn Vue Green Line
• 2008-2010 Chevrolet Malibu Hybrid

[edit] See also

• Two-Mode Hybrid

[edit] References

• "Saturn Vue Greenline". Motor trend. http://www.motortrend.com/features/auto_news/2007/112_news071012_2008_saturn_vue_greenline. Retrieved October 12, 2007. 
• "Going Green". AutoWeek. http://autoweek.com/apps/pbcs.dll/article?AID=/20060108/FREE/60108002/1024/LATESTNEWS. Retrieved January 9, 2005. 
• "Saturn Vue Green Line Hybrid Delivers Great Fuel Economy Through New, Lower-Cost Hybrid System". General Motors press release. http://www.gm.com/company/gmability/adv_tech/100_news/hybridvue2_10906.html. Retrieved January 9, 2006. 
• "Saturn Vue Green Line Uses New, Less Complex Hybrid System". General Motors press release. http://www.gm.com/company/gmability/adv_tech/100_news/hybridvue_10906.html. Retrieved January 9, 2006.