[redpoint5]

Originally Posted by aerohead

I'll apologize if this is redundant info,but I think the VOLT is a parallel hybrid,with no mechanical connection between the engine and drive wheels.It can only provide electrical power to the electric motor,when the pack goes below its design threshold.

That describes a series hybrid, which I used to believe the Volt was. Turns out the Volt is a parallel. The 2nd gen even more so than a Prius since it has an extra clutch that (I believe) allows both Motor/Generators to be used as propulsion motors.

The Voltec drivetrain has three power converting elements:
Primary traction electric motor/generator, provides good acceleration for driving at lower speeds and regeneration for braking, its maximum output of 111 kW setting the maximum output of the whole system.
Secondary electric motor/generator, works primarily as generator capable of producing 55 kW or when necessary acts as a motor assisting the primary electric motor.

Internal combustion engine of 63 kW power, engaged when the batteries reach the predetermined threshold. These units are connected via a planetary gear and three electrically controlled hydraulic clutches to provide power output for propulsion in any of four programmed operating modes:

Single motor electric – The primary motor runs solely on battery power, maximum propulsion power is 111 kW.

Dual motor electric – At higher vehicle speeds the secondary motor engages over the planetary gear such that it reduces the speed of the primary motor. This facilitates higher efficiency and better mileage for the combined system, without increasing the maximum power.

Single motor extended – The battery reaches its minimum charge, which triggers the combustion engine. The engine drives the secondary motor as a generator, via the charging electronics, to keep the minimum battery charge level. The primary motor can still provide its 111 kW for short acceleration, albeit not sustained.

Dual motor extended – The electric motors are used again in dual configuration with increased efficiency at higher speeds. Additionally the gasoline engine contributes propulsion power via the planetary gear. While power is drained from the battery the amount is less than in mode 2 for the same propulsion power, thus extending the range.