Everything That You Want to Know About E-Mobility (But Were Afraid to Ask)

by Lawrence Romanosky on March 27, 2014

Widespread Consumer Acceptance of the Hybrid Vehicle

Porsche Panamera E-Hybrid

We have had Gas-Electric Hybrid vehicles on the road now since 2000, when the first hyper-efficient, tear shaped 2 passenger Honda Insight made its debut.  The Toyota Prius soon followed, with both cars going to early adopters of Green Technology. Several generations later we now see Hybrid vehicles in every market segment, with most car companies selling a Hybrid version of each of their volume model lines. For the most part these cars are identical to their more mainstream counterparts, apart from the more complex and efficient drivetrains.

The interesting thing about the proliferation of Hybrids in the last decade is that much of the growth has happened in the Luxury end of the market, including some extremely expensive Supercars such as the Porsche 918 Spyder.  Part of the reason is that Hybrid powertrains are sophisticated and expensive, and the costs are better absorbed by higher end models – it is easier to add a $5,000 or $10,000 premium to a $100,000 car than a $20,000 one.  Other reasons are that manufacturers are using their Hybrid models as a ‘Halo’ Vehicle to showcase their technological prowess.  The investment in these models is rarely recovered, but the projects are seen as a challenge for the engineering teams to develop technology that will eventually filter down to more mainstream models.

Also, somewhat surprisingly to many, is that Hybrid technology can make the vehicle more fun to drive.  The Electric Motor compliments the Internal Combustion (IC) engine very nicely in a passenger automobile, offering instant torque at low RPM’s where a gas engine feels sluggish.  The electric boost fills out the torque curve which makes the throttle response very linear.  So the rationale behind a Hybrid purchase need not solely be for reasons of efficiency, it can be for performance too.

Mild vs. Strong Hybrids

There are almost as many types of Hybrid drivetrains as there are Hybrid models, but generally speaking, the distinction between a ‘Mild’ Hybrid and a ‘Strong’ Hybrid is due to the extent that the vehicle can travel on electric-only power.

Serial vs. Parallel Hybrids

The two basic types of Hybrids for passenger vehicles are Serial and Parallel.  Serial Hybrids always have the motive force provided by an electric motor – the internal combustion engine and electric motor function in series.  The on-board combustion engine turns an electric motor (generator), which then supplies electricity to a separate electric motor to propel the car.  There is no mechanical link between the IC engine and the powered wheels, and with the relatively high rotational speeds of an electric motor, there is no need for a conventional gearbox.  A downside with the Series Hybrid is that the electricity has to be converted twice; once to power the generator and again to power the wheels – which is less efficient than a gearbox and drive shaft.  Also, with no gearbox, the speed range of the vehicle is limited by the maximum operational speed of the electric motor.

With the ‘Parallel Hybrid’, such as the Panamera S E-Hybrid, the motive force can come from the electric motor, the combustion engine, or both.  The Panamera S E-Hybrid has an electric motor sandwiched between the combustion engine and the gearbox.  The IC engine can be de-coupled and allow the vehicle to ‘Sail’ or ‘Freewheel’, or be driven with just the electric motor.  The electric motor can supply extra ‘boost’ using stored electrical energy, or it can recharge the battery pack from the IC engine or from regenerative braking.  The Porsche 918 Spyder goes one step further by adding a second electric motor on the front axle, which is used to provide electric-only operation as well as AWD capability in its Hybrid modes, though it is necessary to decouple this motor at very high speeds to avoid over-revving it.

Porsche 918 Spyder

Batteries

To have any kind of decent range running on E-Power only, the vehicle will need to have a large battery pack, most likely Lithium-Ion which has twice the capacity of the common Nickel-Metal-Hydride.  These are the same type of batteries as in your laptop or cellphone – an automobile just needs a lot more of them. This battery pack can be charged by the vehicles Combustion Engine, Regenerative Braking, or ideally by plugging the vehicle into the Electrical Grid either though household AC, or by a commercial DC ‘Supercharging’ installation.

A Hybrid vehicle can get away with using a much smaller battery pack than a pure electric vehicle as it has another power source.  A typical ‘Strong’ Hybrid may have a Li-Ion battery pack anywhere from 5kwh to 15 kwhr, which is enough to give electric-only range from between 10km and 55 km.  A small electric vehicle may have a 20 kWh – 30kWh battery pack good for a range of 175 km, but a larger electric vehicle will require 60 kWh to 85 kWh, which gives a range of 300-400 km.

The current costs of a Li-Ion battery run about $500-$600 per kWh, so a large battery pack can cost upwards of $40,000, though costs are thought to decrease by 50% over the next decade.  Most manufactures offer special extended warranties on these battery packs and/or subsidized replacement costs.  Despite Lithium being the lightest metal on the Periodic Table, batteries and the associated heating/cooling and control units are still very heavy; a small 5kWh battery pack weighs about 100kg, and a large pack weighs well over 500kg.

AC/DC Current?

Household electricity is AC, and can not be stored, apart from using a mechanical device such as a flywheel.  All batteries are DC, and automobile electrical systems run on DC power.  For an electric vehicle, it is necessary for the vehicles on-board inverter to change the current from the household AC to DC, before it can be stored in the battery pack, and this limits the speed of charging.  DC charging systems bypass the inverter and charge the battery directly, reducing charging time. These systems are very expensive and generally only suitable for large commercial installations, though Porsche does offer one as an option for the 918 Spyder at $27,000.

Electric Cars and Range Extenders

An Electric car is not a Hybrid, as it only uses one propulsion system – an electric motor and battery pack.  That said many electric cars that are in the works have optional ‘Range Extenders’ which are small combustion engines and generators that help to alleviate range anxiety.  Although they add weight and complexity, they can help with the electrical demands in winter such as heating the cabin and battery pack, blower motors etc. which would normally drastically reduce the vehicles range.

The main obstacles for the pure electric car are the cost of the battery pack, which needs to be much larger than in a Hybrid, charging time, and the charging infrastructure.   Even with a AC 240V 50amp “Stage 2” connection, it will take 4 to 5 hours to charge a large Lithium Ion Battery pack.  Charging a large battery pack with household 110V is not a practical consideration for a daily driver.

There are ‘Fast Charge’ or ‘Supercharger’ stations being built to service electric cars, mostly on the densely populated East and West Coasts, that charge with DC Power directly to the battery, though the cars need special equipment to accommodate this.  These charging systems can recharge a large battery pack in about 45 minutes, although they can give an 80% charge in about half the time (it is the nature of charging a battery that the initial charging is rapid, and then it drastically trails off after the battery is about 80% full.)

At least one Electric car manufacturer has a battery exchange option at its charging stations, whereby the entire battery pack is lowered out of the car and replaced in a mechanized process which can be completed in less time than it takes to fill a conventional vehicle with fuel.

Porsche Panamera E-Hybrid Plugin

Plug-In Hybrids

A Plug-In Hybrid, as the name suggests, allows for the vehicle to be plugged into the electrical mains, and offers several advantages over a standard Hybrid which needs to create most of the electrical power by running the combustion engine.  While complex, the twin power sources alleviate the compromises of a pure electric vehicle, yet still provide the advantages of electric-only operation for commuting distances.  Electricity provided by the Power Grid provides the following benefits:

  1. The cost of ‘filling’ up your car with Electricity from the power grid is only about 20% of the cost of gasoline.
  2. The C02 and other emissions from creating the electricity at power plants are generally less than the emissions created by the internal combustion engines in vehicles, especially if the power comes from wind, solar, hydropower or other ‘clean’ sources.
  3. Where it is necessary to burn fossil fuels to create Electricity, the emissions from Coal and Natural Gas power plants are located away from densely populated areas, and it is easier to monitor the emission of a few power plants rather than millions of vehicles.

Is E-Mobility For You?

There are many factors which influence the viability and cost-effectiveness of electrified vehicles.  Certainly geographic location and the type of driving the vehicle is used for are important considerations.  That said, both the inner city commuter, and the family vacation car, can benefit from the efficiencies of electrification to some degree.  Most manufactures consider Hybrid or Electric vehicles the key to meeting Government mandated average fuel consumption and C02 emission targets.

Electric cars certainly have a future, but have significant compromises for long distance travel – the significant investment that Fast Charging stations require make it unlikely that they will be implemented in low population density areas.  Series Hybrids offer extended range, and can offer certain efficiencies by running a small efficient combustion engine at optimal RPM.  Parallel Hybrids need not give up the sporting characteristics of the Internal Combustion engine and gearbox, and still offer the ability to drive short distances under E-Power.  The Plug-In Parallel is perhaps the best option of all, and is ideally suited to a Sporting automobile that can travel with zero tailpipe emissions in an Urban environment, but also go on longer road trips that may not have an E-Charging infrastructure.

This is the conclusion that Porsche has come to, and the direction that they are taking with E-Mobility.  Our current Plug-In Hybrid line up consists of the 2014 Panamera S E-Hybrid, and the $850,000 USD 918 Spyder: two great cars that quickly refute any suggestions that Hybrids are boring!

Lawrence Romanosky

Sales Manager

Porsche Centre Calgary

{ 0 comments… add one now }

Leave a Comment

Previous post:

Next post:

live chat software