Chevy Volt Surprise

Don Sherman

Volt has two of practically everything: Two forms of portable energy (gasoline and electricity). Two electric motor-generator machines. Two primary modes of operation-using electricity stored in the lithium-ion battery pack or the energy available from 9.3-gallons of premium gasoline carried in a sealed tank. And two distinct transmission ranges. That yields a Rubik's cube of driving possibilities. To provide 40 or so miles of pure-electric operation and 300 or so miles of 'extended' range with the gasoline engine running, the Volt has five distinct operating routines.

Battery-Electric Propulsion

1. Leaving home with a fully charged battery pack provides 40 or so miles of driving range with the engine and generator inoperative. The 149-hp permanent-magnet AC motor draws electricity from the 16kWh battery pack to drive the front wheels through a 7.0:1 speed reducer/torque multiplier.

2. Like any energy-conversion device, electric motors are more efficient at certain operating speeds. When the Volt exceeds fifty mph, a clutch holding the planetary gear set's ring gear is released. A second clutch engages to connect that ring gear to the smaller of the two electric motors. Now both electric motors draw electricity from the battery pack and the effective drive ratio shifts to 2.16:1. Top speed is governed at 100mph.

Hybrid Gasoline and Electric Propulsion

3. When the Volt's battery is depleted to a 30-percent or so state of charge, the gasoline engine is automatically started to give the battery a rest. The clutch connecting the gasoline engine to the smaller electric machine closes so that this device, now acting as a generator, can provide electricity to the main electric-drive motor. Another clutch holds the ring gear fixed, yielding a 7.0:1 overall drive ratio between the motor and the half shafts powering the Volt's front wheels. This regime is used for speeds below 30 mph.

4. At higher cruising speeds, the planetary ring gear is again released, shifting the AC motor drive ratio to 2.16:1. The engine continues providing the power to spin the generator which in turn supplies the drive motor with electric current. In addition, the engine supplies torque to the planetary ring gear through the smaller electric machine. (This is the engine driving-the-wheels scenario heretofore denied by GM.) Operating in this regime, the Volt is both a series hybrid and a parallel hybrid.

If Japan didn't slap outlandish tariffs on made in USA products, I'd say go ahead and get your inferior Prius. Until that changes, why not get the better car - the Volt (you may go months without buying gas at all).
One vehicle missing in this discussion is the Ford FusionHybrid, starting price 28,100.While I located one loaded Ithink you could get less butthis one has all the bells and whistles for 32.915. And has EPA 41 City/ 36 HWY mpg.
In point of fact, the primary AC motor always provides the primary motivation. When the car gets above 70 mph the planetary gears are unlocked and the generator/secondary motor drives the planetary gears, primarily to provide an effective gear reduction to slow the primary motor into a range in which it is more efficient. While undeniable that the generator/motor provides its own torque to the effort to drive the wheels, in this application this is largely a side benefit.Because the engine drives the generator/motor as a generator when the batteries get below 30% charge, above 70 mph the engine is connected to the planetary gears through the generator/motor if the battery charge is too low. While undeniable that, under 1 specific case the engine assists the electric motor in driving the wheels, it is largely a side-effect of the fact that GM borrowed the planetary "transmission" from its own mild hybrid and did not design a completely new "transmission" to always keep the primary AC motor at optimal RPM.
Anyone who buys any hybrid to save money on gas is an uninformed consumer. If you want to have reduced emissions and use less gas for non-economic reasons, fine. Whether you're talking about a Prius, Volt, Leaf, whatever; a small 4 cylinder sedan like a Corolla or Civic is the most cost effective option.After incentives ($7.5 to $9k), a Volt may be competitive with a $28-30k sedan. Whether the extreme cost of battery replacement in 8-10 yrs will affect you should be considered before buying. I have a feeling that GM will have a gov't backed 2,3, or 4 year lease program.
So, you think people will go to the gas station instead of just plugging it in at night??
--All of this assumes people will hassle with plugging-in their Volt. Chances are, they will drive it like a pure-hybrid (which the Volt is not).Better deal is a $23K Prius - That 10 grand in savings will pay for 25 years of gas and you don't have to hassle with plugging-in the Prius.--

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