GM Mild Hybrids: If At First You Don’t Succeed, Try, Try Again

By John Voelcker

1,002 views Nov 16, 2010

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Buick eAssist Hybrid Technology

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The 2011 Chevrolet Volt has gotten all the attention lately, including a narrow second-place finish in our GreenCarReports 2011 Best Car To Buy award, but General Motors also has a significant hybrid-electric vehicle program.

While its full-size Two-Mode Hybrid trucks have had mixed success, the company’s mild-hybrid Belt-Alternator-Starter system did not do well from 2006 to 2009.

From BAS II to eAssist

But GM is nothing if not dogged, and as we reported more than a year ago, a new and far more powerful generation of the BAS system is under development.

Now, as our colleague Vik Vijayenthiran reports, what used to be called “BAS II”—it has now been re-branded eAssist—will be launched as standard equipment on 2012 Buick LaCrosse four-cylinder models.

Will eAssist fare better than the ill-fated first generation? We can’t help but think it will.

Buick eAssist Hybrid Technology

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Leaky battery packs

First, it doesn't use the nickel-metal-hydride battery packs for the first BAS cars that included cells from Cobasys.

While the packs performed as specified, a manufacturing defect that might have caused cell leakage into the pack itself was uncovered after thousands of packs had been built and installed in cars.

That meant that GM had to recall roughly 9,000 mild-hybrid Saturns fitted with first-generation system, both Saturn Vue Green Line crossovers, plus a handful of just-launched Saturn Aura Green Line models.

That significantly delayed the rollout of the Aura hybrid, plus a totally redesigned Vue model, along with the more important Chevrolet Malibu Hybrid, which was projected to sell in higher volume than either niche-market Saturn model. It also impacted the previous-generation Buick LaCrosse EcoHybrid, the only hybrid model GM has sold in China to date.

Fast forward to 2012

Fast forward through collapse, bankruptcy, painful restructuring, and even GM’s initial public offering this week, and look ahead to the 2012 model year.

The eAssist system (nee BAS II) uses a more powerful electric motor—up to 20 kilowatts vs. 5 kW—and a larger lithium-ion battery pack with cells from Hitachi. Apparently unlike Cobasys, Hitachi should have pretty good quality control.

And more than that, the U.S. is now on its way to corporate fuel-economy averages well above 30 miles per gallon, which will require some proportion of every carmaker’s fleet to be hybrid.