• Mar 4th 2008 at 8:45AM
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In mid-2006, General Motors released their first mainstream hybrid vehicle with first Saturn Vue Green Line. Prior to that the company had offered a mild hybrid system in the Silverado pickup but since that was really only offered in limited volumes to fleet and commercial buyers, we'll skip that one. The system in the Vue was dubbed the GM Hybrid system but it's more commonly called the belted-alternator-starter (BAS) system. Since the first Vue, the BAS system has been added to the Saturn Aura and Chevy Malibu as well as the redesigned 2008 Vue.

Last fall at the Frankfurt Motor Show GM showed a concept Opel Corsa with an updated version of the BAS system. At the time GM declined to give any details of the system other than the fact it had a lithium ion battery. At the Geneva Motor Show today, GM Chairman Rick Wagoner is announcing that the next-generation GM Hybrid system will go into production in 2010. More importantly, the upgrades to the system will make it more suitable for a much larger range of applications and production of the system will be increased dramatically. Learn more about the second generation of GM's mild hybrid system after the jump.

[Source: General Motors]

The BAS system has been criticized by many since it's debut for it's limited gains in fuel efficiency compared to hybrids from Toyota, Honda and Ford. In some applications that criticism has been pretty valid, with the Saturn Aura hybrid only picking up 2mpg over the conventional four-cylinder model. The new Vue on the other hand gets a 27 percent bump in mileage going from the base four cylinder to the hybrid. The one advantage that the system has had over competitors is cost. The price premium for the BAS system is typically only about $1,600-1,700.

The GM Hybrid system is actually pretty straightforward and requires relatively little in the way of changes to the base vehicle. The heart of the system is the motor/generator. The standard alternator is replaced by a unit that looks very similar but has the capability to provide extra drive assist to the engine. To do that GM had to develop a belt drive system with two idler tensioners to allow the motor to drive the engine as well as the other way around.

Normally the forces acting the drive belt only act on one side of the belt as the engine pulley pulls the belt to drive the alternator. The other side of the drive belt would be slack as the engine pulley can't push on a rubber belt. The idler takes up this slack. If the motor is driving the engine, it's pulling on the normally slack side and the reverse side would go slack requiring a second idler pulley.

All of this allows the motor/generator to provide automatic start/stop capability, motor the engine along with fuel shutoff during coast down, provide electrical power boost under acceleration and regenerative braking. Electrical energy for the current generation of the system is stored in a 36V nickel metal hydride battery. The 5kW capacity of the motor/generator and 36V output of the battery limits the application capability of the system which is why it's only available with the 2.4L four cylinder in three applications.

When GM showed the updated system in the Corsa last fall, it was paired up with a 1.3L turbodiesel. When the new system launches two years from now it will have the capability to be used with many more drivetrains, including diesels and flex-fuel engines. That's because an all-new motor generator using different technology will provide three times the power of the current unit while fitting into roughly the same package size. During a pre-show backgrounder, GM officials declined to say exactly what the nature of the new motor design was. GM also declined to get specific about the output of the new motor although 15kW is a good estimate and would put it at the same range as the mild hybrid system being developed by Mercedes-Benz and BMW.

The same basic drive system will be retained although it is upgraded to handle the extra power. Of course a more powerful motor and generator needs more electrons and place to store them. For a system that's intended to be applied globally to a wide range of vehicles and engines, a nickel battery won't cut it.

The new system switches over to a lithium ion power battery. Again GM was short on details, but they did give us some tantalizing hints. While Stephen Poulos, chief engineer for the hybrid system declined to reveal exactly what the battery voltage would be, it will be more than the 36V of the current system and less than the 300V used in the Two-Mode system. Somewhere around 100V seems to be a good bet.

The new pack will be 24 percent smaller in volume than the current NiMH unit. It will weigh forty percent less and have thirty-three percent more power. The smaller more powerful battery will give GM better packaging flexibility helping to make the system more adaptable to other applications.

The control software for the current system is completely different from the two-mode system. While developing the two-mode, GM engineers made the software architecture scalable and flexible so that it could be used with different hybrid applications. That includes the mild hybrid which will now use the same software base.

The low power capability of the current system means that it's not practical for use on bigger vehicles. The increased power output and energy storage of the new version makes it suitable for use with almost every mainstream application GM has. During the presentation Poulos provided an application example that started with the 3.6L V-6 that GM uses in numerous applications including the Lambda platform crossovers. That engine produces around 260hp depending on the application.

As an alternative, Poulos showed a turbocharged 2.4L four cylinder that matched the torque curve of the V-6 above 3,000rpm but was lacking at the lower regions where most drivers spend most of their time. With the next-gen mild hybrid system providing a torque assist at lower engine speeds in combination with the turbo four, the overall curve matched or exceeded the larger engine. While the current Two-Mode hybrid apparently doesn't fit in the Lambda engine compartment, this system definitely would. While matching performance, the turbo hybrid combination is smaller, lighter and more efficient.

While GM was undeniably reticent about getting too specific more than two years ahead of the production launch, they expect the new system to deliver a 15-20 percent boost in fuel economy compared to a similarly powerful conventional system. They also declined to say which vehicles would get the system, although the current vehicles are an obvious start.

However, the fact that they chose to announce the system in Geneva is a clear system that they intend to offer this system in every market they operate in. The system will be compatible with both front and rear wheel drive systems, so it seems likely that we'll see the new hybrid on rear drive cars like the Pontiac G8 and Chevy Camaro. While hybrids haven't been particularly in Europe to date, the coming of CO2 limits in Europe will require companies like GM to go beyond the diesels they currently offer.

GM also declined to say how the manufacturing cost compares between the current and next gen systems. They did say that they expect the customer cost to be similar to the current system and it will be profitable quickly as volumes climb. No one would say on the record how high they expect volumes to go, but all indications are that 100,000 per year is strictly a jumping off point.

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    • 1 Second Ago
      • 7 Years Ago
      No one was interested in _purchasing_ large-format NiMH batteries in OEM quantities until recently, with the Aura.

      Hobbyists were upset Cobasys wouldn't sell them NiMH batteries for one-off conversions.

      Battery research long ago moved on to lithium-ion technologies - NiMH is simply inadequate for series hybrids like the Volt.
      • 7 Years Ago
      When GM introduced the EV1, it had the chance to leap frog all the car companies, even with Pd batteries had they been smart about costing the batteries by leasing them. Remember they owned 60% of the NiMH patent company, Ovonics. But they gave way to the oil companies and helped create a "red herring" called The Hydrogen fuel cell. Some say this was done in agreement not only with the oil companies and our oil President/Vice President. And this might very well be true because GM sold their 60% Ovonics interest to the oil companies who have suppressed the development of a large format NiMH battery for automobile use ever since.

      GM suffers from one major problem, it is obsessed with counting its beans when good engineering decisions would have assured an excellent supply of beans going forward. When they needed an enginering guy on the bridge, they found themselves depending on accountants.
      • 7 Years Ago
      Suburban 2500, 5.3 VCT 6L90 (these guys like to tow)
      4x2 3.73
      4x4 4.1
      Suburban 1500 5.3 VCT 6L80
      4x2 3.73
      4x4 4.1 (hey, those are the same as the 2500!? Yes, but the 2500 has smaller tires 245/75 16 vs 265/75 16. The tow 'guys/gals' like cheaper tires to 'burn through')
      Tahoe 5.3 VCT 6L80
      4x2 3.42
      4x4 3.73
      If that doesn't happen for '09, GM should just sell the company to the Chinese and be done with it.
      • 7 Years Ago
      it was so predictable. Another GM milestone announcement that is a drop in the ocean.
      • 7 Years Ago
      I really hope GM has new engines for 2010 [calendar year?].
      How about direct injection on the 2.4?
      What about the 2.2 I4? It gets variable intake & exhaust valve timing for '09 MY.
      What about the 2.8 & 3.2 versions of the V6?

      GM's problem isn't over-horsepower, it is under-transmission.

      For '08 GM sells the Tahoe with a 4 speed automatic. Unbelieveable.
      Replace the 4L60 with the 6L80, add VCT to the 5.3 V8 [circa 330hp, 350ft-lbs] and the performance should scare the sh*t out of prospective customers.
      'Yeah this 5500+lb vehicle can get to 100mph in 1/3 of a mile'

      Then they will realize that they don't need but 75% of that.
      Say a 250hp, 375ft-lb diesel V6.
      or lob two cylinders off the LS3 V8 for a 4.6 liter V6. 315hp, 315ft-lbs, on regular.
        • 6 Years Ago
        The 2.4-liter four and 3.0-liter V6 are both available now with direct injection in the 2010 Chevy Equinox and will be launching over the next several months in the Cadillac SRX and CTS (V6 only), the 2010 Buick LaCrosse, and the GMC Terrain. Both engines will also likely migrate to other models like the Malibu and more over the next year.
        • 6 Years Ago
        Mike, i think there is a 3.0 DI v6 coming out next year in the SRX and soon to spread, and they added DI to the 2.4 liter for next year, I know it get 32 mpg in the upcoming equinox, i am curious to see how it would do in a 6spd malibu, or even better, at a smaller displacement in a small car.
      • 7 Years Ago
      @ Lad,

      Just curious - where was the market for the EV1? Do you really think GM killed it because of the wishes of big oil? If there was a real public interest in it, the program wouldn't have died. But counting up all years of EV1 production, you might get maybe 1100 cars. That's not even close to a month's Toyota Tundra sales.

      GM saw what it had, and decided not to keep going. This happens alot to many programs "ahead of their time".

      And as for the new BAS - sounds like an easy way for GM to get a quick bump in MPG to try and meet the 35MPG by 2020 (or 44 MPG if California wins vs. the EPA) and remain profitable.
      • 7 Years Ago
      A quicker solution would address GM's Insane Over-Capacity of horsepower in all models.

      • 7 Years Ago
      5mph, it sounds like the Honda Civic hybrid.
      25mph on battery alone in the Prius.

      • 7 Years Ago
      Sam -

      at constant ohmic resistance (i.e. same cables), power in DC systems is proportional to the square of the applied voltage. Upgrading the system from 5kW to ~15kW would therefore require going from 36V to ~64V. GM might still decide to go for 110V regardless.

      Combining reduced displacement/cylinder count, GDI, turbocharging and a mild hybrid system sounds attractive but is expensive. Since GM already has an inline 4 with 600cc per cylinder, they may want to consider applying ~20% low pressure EGR and a regular VGT turbo (Ricardo's EGR-boost concept) to deal with turbo lag and modest torque at low RPM. A cheap 12V start-stop system based on an AGM lead-acid battery plus efficiency small fry (intelligent alternator control, electric water pump, thermal management, variable flow volume oil pump etc.) would complete the picture.

      The torque curve would not match that of the 3.6L V6, but money saved on the hybrid components can then be applied toward a 6-7 speed dual clutch transmission and/or shaving weight off the vehicle. The idea is to replicate vehicle performance while improving fuel economy.
      • 7 Years Ago
      Looks as tho the General intends to keep laming along with these BAS until they can leapfrog the parallel hybrids with the series hybrid, even their two-mode hybrid system could be adapted to series arrangement.

      It will be inetresting to see if any bright bulbs over at Chrysler have the idea of combining their 3.0 V6 bluetec diesel with their version of the same two-mode hybrid transmission yielding a Dodge Durango or Jeep Grand Cherokee or Ram 1500 pickup with mileage in the mid to high 30's. -SpinDaddy
      • 7 Years Ago
      OOPS. To wrap up my point: I believe GM is taking the "mediocre" option because its goal is to make a profit, not make a car that uses less fuel.

      GM has to adopt because it cannot ignore the potential market for hybrids, yet at the same time, it doesn't want to bet the farm on fuel-saving vehicles because history is likely to repeat itself; people will easily give up on hybrids and move onto the next fad. I see that GM will continue to ride the PR campaign on the Volt and sell just a few hybrids here and there. When the market for hybrid truly matures, then maybe we'll see some serious competition from GM in the next decade.
      • 7 Years Ago
      Regarding your comment no. 19, Thanks---you beat me to the punch. Sure, we all would like to see huge efficiency gains instead of smaller, incremental ones, but progress is still progress. People should give credit and encouragement where it's due.
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