The drive system of the Mercedes-Benz SLS AMG E-CELL: Advanced technology made visible

PRESS RELEASE

With the electric drivetrain system of the SLS AMG E-CELL, Mercedes-AMG GmbH is providing yet another glimpse of its latest development project. The drivetrain has been in development since 2010 as a result of the cooperation between Mercedes-AMG and Mercedes AMG High Performance Powertrains in Brixworth. Four synchronous electric motors located near the wheels, providing a peak output of 392 kW and torque of 880 Nm, help to provide the SLS AMG E-CELL with its exciting driving dynamics. The carbon-fibre transmission tunnel, which also serves as the monocoque housing for the high-voltage battery modules, is structurally integrated into the aluminium body shell and firmly bonded to it. The lightweight fibre composite materials have their origins in the world of Formula 1, among other areas.

A small series-production run of the Mercedes-Benz SLS AMG E-CELL is expected to be launched onto the market in 2013. The powerful and locally emission-free super sports car with electric drive is yet another example of the innovative strength and development competence of the AMG performance brand.

The ground-breaking drive system of the technology vehicle boasts some outstanding features: powerful traction is provided by four synchronous electric motors with a combined peak output of 392 kW and a maximum torque of 880 Nm. The four compact electric motors each achieve a maximum rotational speed of 12,000 rpm and are positioned close to the wheels. As a result, compared with wheel-hub motors, the unsprung masses are substantially reduced. One transmission per axle transmits the power.

Acceleration from zero to 100 km/h in 4 seconds
When it comes to dynamics, the electrically-powered SLS makes a statement: the gullwing model accelerates from zero to 100 km/h in 4 seconds – which almost puts it on the same high level as the SLS AMG with 6.3-litre V8 engine developing 420 kW (571 hp), which can accelerate to 100 km/h in 3.8 seconds.

Further exciting touches are provided courtesy of the agile accelerator response and the straight-line performance: unlike a combustion engine, torque build-up in an electric motor is instantaneous – maximum torque is available virtually from a standstill. The spontaneous torque build-up and confident power delivery - which does not suffer from any interruption of tractive power - are combined with engine running characteristics which are totally free of vibration.
The key data at a glance:

SLS AMG E-CELL
Max. output: 392 kW
Torque: 880 Nm
0 - 100 km/h: 4.0 s
Energy content: 3 x 16 kWh = 48 kWh

All-wheel drive with torque vectoring enables completely new levels of freedom
Four wheels, four motors – the intelligent and permanent all-wheel drive of the electric SLS guarantees driving dynamics at the highest level, while at the same time providing the best possible active safety. Optimum traction is therefore ensured, whatever the weather conditions. According to the AMG developers, "torque vectoring" involves the individual control of the electric motors, something which enables completely new levels of freedom to be achieved. Torque vectoring is permanently active and allows for selective distribution of forces for each individual wheel. The intelligent distribution of drive torque greatly benefits driving dynamics, handling, driving safety and ride comfort. Each individual wheel can be electrically driven and electrically braked, depending on the driving conditions, thus helping to optimise the vehicle's cornering properties, reduce the tendency to oversteer/understeer, increase the yaw damping of the basic vehicle, reduce the steering effort and steering angle required, increase traction, and minimise ESP® intervention.

Torque vectoring enables optimum use of the adhesion potential between the tyres and the road surface in all driving conditions, thereby extending the critical limits of the vehicle's driving dynamics.

Advanced technology from Formula 1: high-voltage lithium-ion battery
The SLS AMG E-CELL incorporates a liquid-cooled high-voltage lithium-ion battery featuring a modular design with an energy content of 48 kWh. Its development has made use of advanced technology from the world of Formula 1: the battery is the first result of the co-operation between Mercedes-AMG GmbH in Affalterbach and Mercedes AMG High Performance Powertrains (formerly Mercedes-Benz High Performance Engines). Headquartered in Brixworth, England, the company has been working closely with AMG for a number of years. F1 engine experts have benefited from its extensive expertise with the KERS hybrid concept, which made its debut in the 2009 Formula 1 season. At the Hungarian Grand Prix in 2009, Lewis Hamilton achieved the first historic victory for a Formula 1 vehicle featuring KERS hybrid technology in the form of the Mercedes-Benz KER System.

The high-voltage battery consists of 12 modules each comprising 72 lithium-ion polymer cells. This optimised arrangement of a total of 864 cells has benefits not only in terms of best use of the installation space, but also in terms of performance. The maximum electric load potential of the high-voltage battery is 480 kW, which is an absolute best value in the automotive sector. Another technical feature of this considerable performance is the intelligent parallel circuit of the individual battery modules – this also helps to maximise the safety, reliability and service life of the battery. As in Formula 1, the 400-volt battery is charged by means of targeted recuperation during braking whilst the car is being driven.

High-performance control as well as effective cooling of all components
A high-performance electronic control system converts the direct current from the high-voltage battery into three-phase alternating current which is required for the synchronous motors and regulates the energy flow for all operating conditions. Two low-temperature cooling circuits ensure that the four electric motors and the power electronics are maintained at an even operating temperature. A separate low-temperature circuit is responsible for cooling the high-voltage lithium-ion battery. In low external temperatures, the battery is quickly brought up to operating temperature with the aid of an electric heating element. This helps to preserve the overall service life of the battery. In extremely high external temperatures, the cooling circuit for the battery can be additionally boosted with the aid of the air conditioning system.

"AMG Lightweight Performance" design strategy
The trailblazing body shell structure of the SLS AMG E-CELL is part of the ambitious "AMG Lightweight Performance" design strategy. The battery is located within a carbon-fibre monocoque which forms an integral part of the body shell and acts as the gullwing model's "spine". The fibre composite materials have their roots in the world of Formula 1, among other areas. The advantages of carbon-fibre were exploited by the AMG engineers in the design of the monocoque. These include their high strength, which makes it possible to create extremely rigid structures in terms of torsion and bending, excellent crash performance and low weight. CFRP components are up to 50 percent lighter than comparable steel ones, yet retain the same level of stability. Compared with aluminium, the weight saving is still around 30 percent, while the material is considerably thinner. The weight advantages achieved through the carbon-fibre battery monocoque are reflected in the agility of the SLS AMG E-CELL and, in conjunction with the highly innovative wheel-selective four-wheel drive system, ensure true driving enjoyment.

The carbon-fibre battery monocoque is, in addition, conceived as a "zero intrusion cell" in order to meet the very highest expectations in terms of crash safety. It protects the battery modules inside the vehicle from deformation or damage in the event of a crash.

The basis for CFRP construction is provided by fine carbon fibres, ten times thinner than a human hair. A length of this innovative fibre reaching from here to the moon would weigh a mere 25 grams. Between 1000 and 24,000 of these fibres are used to form individual strands. Machines then weave and sew them into fibre mats several layers thick, which can be moulded into three-dimensional shapes. When injected with liquid synthetic resin, this hardens to give the desired structure its final shape and stability.

Through their experience with the SLR, the AMG Black Series vehicles and in motorsport, Mercedes-Benz and AMG have accumulated more than 10 years of expertise in working with carbon-fibre materials. AMG currently makes the propshaft for the SLS AMG, for example, in carbon-fibre. On the SLS Roadster, the supporting structure for the draught-stop is made as standard as a carbon sandwich structure. This component, with extremely short cycle times in an industrially oriented manufacturing process, already demonstrates what will be possible in the future.

Optimum weight distribution and low centre of gravity
The purely electric drive system was factored into the equation as early as the concept phase when the gullwing model was being developed. It is ideally packaged for the integration of the high-performance, zero-emission technology: by way of example, the four electric motors and the two transmissions can be positioned as close to the four wheels as possible and very low down in the vehicle. The same applies to the modular high-voltage battery. Advantages of this solution include the vehicle's low centre of gravity and balanced weight distribution – ideal conditions for optimum handling, which the electrically-powered gullwing model shares with its petrol-driven sister model.

New front axle design with pushrod damper struts
The additional front-wheel drive called for a newly designed front axle: unlike the series production vehicle with AMG V8 engine, which has a double wishbone axle, the SLS AMG E-CELL features an independent multi-link suspension with pushrod damper struts. This is because the vertically-arranged damper struts in the series SLS had to make way for the additional drive shafts. As is usual in a wide variety of racing vehicles, horizontal damper struts are now used, which are operated via separate push rods and transfer levers.

Thanks to this sophisticated front-axle design, which has already been tried and tested in the world of motorsport, the agility and driving dynamics of the SLS AMG E-CELL attain the same high levels as the V8 variant. Another distinguishing feature is the speed-sensitive power steering with rack-and-pinion steering gear: the power assistance is implemented electrohydraulically rather than just hydraulically.

AMG ceramic composite brakes for perfect deceleration
The technology vehicle is slowed with the aid of AMG high-performance ceramic composite brakes, which boast extremely short stopping distances, a precise actuation point and outstanding fade resistance, even in extreme operating conditions. The over-sized discs – measuring 402 x 39 mm at the front and 360 x 32 mm at the rear – are made of carbon fibre-strengthened ceramic, feature an integral design all round and are connected to an aluminium bowl in a radially floating arrangement.

The ceramic brake discs are 40 percent lighter in weight than the conventional, grey cast iron brake discs. The reduction in unsprung masses not only improves handling dynamics and agility, but also ride comfort and tyre grip. The lower rotating masses at the front axle also ensure a more direct steering response – which is particularly noticeable when taking motorway bends at high speed. The ABS and ESP® systems have been adapted to match the special application spectrum of the permanent all-wheel drive.

Mercedes’ Electric SLS Revealed

Mercedes finally unveiled the powertrain of its upcoming SLS eCell electric, gullwing supercar … and it is all kinds of high-tech, carbon fiber awesome.

The new AMG-developed, aluminum-bodied coupe features a pushrod front suspension to minimize unsprung weight (handling’s mortal enemy) in a bid to offset the weight penalties of carrying an electric motor in each of the car’s four wheels. The layout allows the car’s computers to vary torque to each wheel – a system similar in concept to Honda’s NSX supercar – that maximizes traction off the line and in slippery conditions while keeping the car’s balance predictably neutral.

Source: Gas2.0

Mercedes-Benz provides an update on the electric drivetrain of the SLS AMG E-CELL

New rendering of the electric drivetrain of the SLS AMG E-CELL showing modifications to packaging and layout of some components. Click to enlarge.

The drivetrain of the battery-electric Mercedes-Benz SLS AMG E-CELL sports car has been in development since 2010 as a result of the cooperation between Mercedes-AMG and Mercedes AMG High Performance Powertrains in Brixworth. (Earlier post.) A small series-production run of the Mercedes-Benz SLS AMG E-CELL is expected to be launched onto the market in 2013. Mercedes-Benz has now provided an update on the drivetrain.

Four synchronous electric motors located near the wheels provide a peak output of 392 kW and torque of 880 N·m (649 lb-ft). The carbon-fibre transmission tunnel, which also serves as the monocoque housing for the high-voltage battery modules, is structurally integrated into the aluminium body shell and firmly bonded to it. The lightweight fibre composite materials have their origins in the world of Formula 1, among other areas.

2011 rendering of the drivetrain components. Click to enlarge.

The gullwing model accelerates from zero to 100 km/h in 4 seconds – which almost puts it on the same high level as the SLS AMG with 6.3-liter V8 engine developing 420 kW (571 hp), which can accelerate to 100 km/h in 3.8 seconds.

The four compact electric motors each achieve a maximum rotational speed of 12,000 rpm and are positioned close to the wheels. As a result, compared with wheel-hub motors, the unsprung masses are substantially reduced. One transmission per axle transmits the power.

The resulting permanent all-wheel drive of the electric SLS enables torque vectoring via the individual control of the electric motors for selective distribution of forces for each individual wheel. The intelligent distribution of drive torque greatly benefits driving dynamics, handling, driving safety and ride comfort. Each individual wheel can be electrically driven and electrically braked, depending on the driving conditions, thus helping to optimize the vehicle’s cornering properties, reduce the tendency to oversteer/understeer, increase the yaw damping of the basic vehicle, reduce the steering effort and steering angle required, increase traction, and minimize ESP intervention.

The SLS AMG E-CELL incorporates a liquid-cooled high-voltage lithium-ion battery featuring a modular design with an energy content of 48 kWh. Its development has made use of advanced technology from the world of Formula 1—the battery is the first result of the co-operation between Mercedes-AMG GmbH in Affalterbach and Mercedes AMG High Performance Powertrains (formerly Mercedes-Benz High Performance Engines). Headquartered in Brixworth, England, the company has been working closely with AMG for a number of years.

F1 engine experts have benefited from its expertise with the KERS hybrid concept, which made its debut in the 2009 Formula 1 season. At the Hungarian Grand Prix in 2009, Lewis Hamilton achieved the first historic victory for a Formula 1 vehicle featuring KERS hybrid technology in the form of the Mercedes-Benz KER System.

The high-voltage battery consists of 12 modules each comprising 72 lithium-ion polymer cells. This optimized arrangement of a total of 864 cells has benefits not only in terms of best use of the installation space, but also in terms of performance. The maximum electric load potential of the high-voltage battery is 480 kW—a best value in the automotive sector. Another technical feature is the intelligent parallel circuit of the individual battery modules which helps to maximize the safety, reliability and service life of the battery. As in Formula 1, the 400-volt battery is charged by means of targeted recuperation during braking while the car is being driven.

A high-performance electronic control system converts the direct current from the high-voltage battery into three-phase alternating current which is required for the synchronous motors and regulates the energy flow for all operating conditions. Two low-temperature cooling circuits ensure that the four electric motors and the power electronics are maintained at an even operating temperature.

A separate low-temperature circuit is responsible for cooling the high-voltage lithium-ion battery. In low external temperatures, the battery is brought up to operating temperature with the aid of an electric heating element. This helps to preserve the overall service life of the battery. In extremely high external temperatures, the cooling circuit for the battery can be additionally boosted with the aid of the air conditioning system.

The body shell structure of the SLS AMG E-CELL is part of the “AMG Lightweight Performance” design strategy. The battery is located within a carbon-fibre monocoque which forms an integral part of the body shell and acts as the gullwing model’s “spine”. CFRP components are up to 50% lighter than comparable steel ones, yet retain the same level of stability. Compared with aluminium, the weight saving is still around 30%, while the material is considerably thinner.

The carbon-fibre battery monocoque is, in addition, conceived as a “zero intrusion cell” for crash safety. It protects the battery modules inside the vehicle from deformation or damage in the event of a crash.

Through their experience with the SLR, the AMG Black Series vehicles and in motorsport, Mercedes-Benz and AMG have accumulated more than 10 years of expertise in working with carbon-fibre materials. AMG currently makes the propshaft for the SLS AMG, for example, in carbon-fibre. On the SLS Roadster, the supporting structure for the draught-stop is made as standard as a carbon sandwich structure. This component, with extremely short cycle times in an industrially oriented manufacturing process, already demonstrates what will be possible in the future, Mercedes-Benz says.

The purely electric drive system was factored into the equation as early as the concept phase when the gullwing model was being developed. The four electric motors and the two transmissions are positioned as close to the four wheels as possible and very low down in the vehicle; the same applies to the modular high-voltage battery. Advantages of this solution include the vehicle’s low centre of gravity and balanced weight distribution—ideal conditions for optimum handling, which the electrically-powered gullwing model shares with its gasoline-driven sibling.

The additional front-wheel drive called for a newly designed front axle: unlike the series production vehicle with AMG V8 engine, which has a double wishbone axle, the SLS AMG E-CELL features an independent multi-link suspension with pushrod damper struts. This is because the vertically-arranged damper struts in the series SLS had to make way for the additional drive shafts. As is usual in a wide variety of racing vehicles, horizontal damper struts are now used, which are operated via separate push rods and transfer levers.

Due to this front-axle design, the agility and driving dynamics of the SLS AMG E-CELL attain the same high levels as the V8 variant. Another distinguishing feature is the speed-sensitive power steering with rack-and-pinion steering gear: the power assistance is implemented electrohydraulically rather than just hydraulically.

The vehicle uses AMG high-performance ceramic composite brakes, which feature extremely short stopping distances, a precise actuation point and excellent fade resistance, even in extreme operating conditions. The over-sized discs—measuring 402 x 39 mm at the front and 360 x 32 mm at the rear—are made of carbon fibre-strengthened ceramic, feature an integral design all round and are connected to an aluminium bowl in a radially floating arrangement.

The ceramic brake discs are 40% lighter in weight than the conventional, grey cast iron brake discs. The reduction in unsprung masses not only improves handling dynamics and agility, but also ride comfort and tire grip. The lower rotating masses at the front axle also ensure a more direct steering response—particularly noticeable when taking curves at high speed. The ABS and ESP systems have been adapted to match the special application spectrum of the permanent all-wheel drive.

Source: Green Car Congress

Daimler testing B-Class E-Cell plug-in hybrid with inductive charging

PRESS RELEASE

The idea sounds as easy as convincing: Instead of „filling up" an electric vehicle by cable the driver parks conveniently above the power source when using contactless inductive charging of the battery. The charging process starts automatically as soon as the car is parked over a charging point. Additional advantages come to the fore especially in public areas: The inductive charging points can be integrated into the ground safe from vandalism.

Currently widespread inductive charging is still a long way off. Yet to test feasibility of such a system Daimler and Conductix-Wampfler have elaborated the basics for wireless charging of electric vehicles in a research project cofunded by the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (Bundesministerium für Umwelt, Naturschutz und Reaktorsicherheit, BMU). Main target of the project "wireless charging" was a safe, automotive grade charging system with maximum efficiency and minimum weight and package.

More Comfort and High Efficiency
Goal of the field test was to evaluate everyday-usability of wireless charging as well as to probe advantages and disadvantages in comparison with charging by plug and cable. As early as a few days into the field test the advantages customer comfort and charging safety by the automated charging process became apparent.

The testing focused on the basic charging process. Efficiency of the system admittedly still doesn´t match charging by cable, but is with 90 percent already very promising and only slightly beneath cable based solutions, if all components from socket to battery are taken into account.

There was an evaluation of the first "driving-experiences" with study participants who had to "drive onto the optimum charging position". After two or three exercise runs this could be well achieved supported by parking assistance functions. The system tolerates smaller deviations within the range of a few centimeters without noteworthy loss of charging efficiency or transferable power. Also, the system showed already good results regarding electro magnetic compatibility. It is the task of future engineering work to optimize this as well as to improve efficiency and to develop solutions for a series application.

Technology and Vehicle
The protototypes built within the project on the basis of the B-Class E-CELL with range extender are equipped with an electronic rectifier and a collector coil integrated into the underbody cover. Main components on the infrastructure side are the supplying electronic and the charging coil, which was realized in two variants – as an above ground and beneath ground coil.

Besides the wireless energy transfer other functional aspects are the wireless communication between infrastructure and car, the driver assistance function "driving onto the position above the charging coil", the automatic start of the charging process and the vehicle identification. In the area between the coils an object detection avoids risks by warmed metal items.

Detailed scientific studies generated the foundation for the first layout of the inductive transfer components with automotive specific requirements and their optimization regarding package and weight. Comprehensive system simulations served to validate the designs.

Conductix-Wampfler has developed all components of the system and could rely during the process on comprehensive experience with inductice power transfer in manufacturing automation as well as on know-how from the wireless charging of electric busses in Genoa and Turin. These are in operation since 2003.

Daimler has defined the functions of the charging system on the car´s side and realized the assistance system for driver support. The system was integrated into two vehicles with range extender, nameplate Mercedes-Benz B-Class E-CELL Plus. The coil integration within the underbody cover of the cars was designed and supplied by Röchling Automotive.

After the prototype vehicles had been built the complete system was mechanically and electrically integrated and taken into operation as a whole. Two inductive charging stations are in the field at the Daimler-Engineering-Location Böblingen-Hulb and are intensively used for the everyday-tests.

Résumé and Outlook
First conclusions confirm the considerable gain of comfort in comparison with cable based charging and that inductive charging is suitable in principle. The potential optimization regarding package, weight and integration in future vehicle model lines is identified and will accordingly be further developed.

At the same time an evaluation is done on new common projects with potential inductive charging applications in small commercial vehicles and busses. The results of the current tests are important to national and international standardization activities – with the aim to guarantee interoperability of inductive charging systems of different suppliers and vehicle manufacturers.

Short Profile Conductix-Wampfler
Conductix-Wampfler is the world's leading supplier of mobile energy supply and data transmission systems. With own companies and several partners Conductix-Wampfler is present in nearly all relevant countries. With about 1.000 employees across the globe, the group generated sales of over € 177 million in fiscal 2010.

Daimler Director Explains Approach to Fuel Cells and Battery Electric Vehicles

The Mercedes-Benz B-Class F-Cell hydrogen fuel cell car in San Francisco.

Last week, I took a spin in the Mercedes-Benz B-Class F-Cell hydrogen fuel cell car, on the San Francisco leg of the “F-Cell World Drive.” As with almost all pure electric-drive cars, the ride was brisk, quiet and smooth—an uneventful ride that belies the profound transformation that battery- and fuel-cell-powered cars represent to the future of automobiles.

After the short drive, I caught up with Dr. Christian Mohrdieck, Daimler’s director of fuel cell and battery drive development, to learn about Daimler’s official positions on EVs versus fuel cell cars. In one sense, the company’s position seems contradictory. After all, Mercedes has a decent list of battery-powered cars on its roadmap: the A-Class E-Cell (produced in limited numbers in Europe); the Smart ED currently on lease in the United States; the S-Class plug-in hybrid (with 20 miles of all-electric range) announced in Frankfurt last year; and a four-seat electric car planned for production in partnership with Renault.

Yet, Dr. Mohrdieck makes no bones about his views on the limitation of electric cars. “If you need a larger vehicle, if you need long range, if you need short refueling times, then you have to have something else than batteries,” he told me.

Q and A

Dr. Christian Mohrdieck, director of fuel cell and battery drive development at Daimler.

Is the company putting as much emphasis on the F-cell as the E-cell (electric car)?

Yes. One way to see this is we are putting similar budgets on fuel cells and batteries at this point in time. There’s much more going to internal combustion engines and hybrids, because they are already high volume products. But we need to invest in the future and we try to do this in a very consistent and balanced way.

How rapidly is battery technology improving? And how fast is cost coming down?

I think battery technology has improved over the last decade to 15 years, and there’s still room for improvement. Battery progress is very tough. People think progress is faster than it really is. We want to get to $280 to $300 per kilowatt-hour in about 10 years. Right now, it’s about three times that cost.

How does this cost compare to the overall cost of fuel cell technology?

The cost of fuel cell technology per kWh is lower. The overall absolute system cost is higher because we have much more power on the fuel cell. But the potential for cost reduction on fuel cells is much bigger. Projections from MIT, for example, say fuel cell vehicles in the long run will be cheaper than battery electric vehicles. That’s one other reason we need to pursue this technology in parallel.

With the hope that hydrogen fuel infrastructure comes along?

That’s a hope you have for battery electric vehicles too, because most people driving city compact cars at least in Europe, they don’t have a garage. They don’t have a parking spot, so they need infrastructure because they’re living on the 10th floor. So, infrastructure is needed for battery-electric vehicles too. And you want to charge quicker than just with the grid, which takes many hours to charge.

Does the issue of net energy gain or loss to produce the hydrogen concern you?

Yes, the same thing concerns me with electricity. In the European Union’s regular electricity mix, the battery electric car is worse than the hydrogen fuel cell car when you make the hydrogen from natural gas, because there’s still a lot of fossil energy used to make electricity,

The efficiency of the battery electric car per se is higher because you don’t have so many conversion steps. Everything depends on how you make the electricity. Eventually, we want to make hydrogen from renewable sources, like solar, wind, hydro, and biomass. And then you have a very low CO2 level and you have all the advantages of cars today: long range, three-minute refueling, and it can be applied to even city buses, so very big vehicles.

Do you think the current rollout of battery electric vehicles from Japanese and American carmakers is happening too rapidly?

No. Because I see they are already changing their numbers. Nissan has reduced numbers and delayed introduction times, so I think nobody can ignore reality of electro-chemistry. I think the problems to be solved are the same for everybody.

How active is your partnership with Tesla?

It’s very active. Actually, I visited them today. They’re delivering batteries for two of our vehicles, the Smart and the A-Class. In order to have enough energy on the A-class E-cell, we put two batteries from the Smart EV, and we connected the batteries in a certain way. They are working together, to provide approximately 36 kWh. We have a lot room in this double floor (on the A-Class and B-Class) under the passenger compartment, and two batteries used in the Smart easily fit into the A-Class.

Daimler believes that battery-electric technology is ideally suited to small cars, like the Smart ED, but not for vehicles larger than compact size. (Photo by Sebastian Blanco, AutoblogGreen)

What’s your view of Tesla’s battery strategy?

I think it’s a very good solution for now, but Tesla already is working on the next generation, where they will improve the consumer cells in order to better meet automotive requirements. The size will be the same and the capacity will be very similar. I think they have a very sophisticated concept of connecting the cells, and managing the cells—and their battery electronics is a very intelligent and sophisticated system able to control the many thousand cells in their Roadster and our Smart and A-Class. [Note: Later, Dr. Mohrdieck responded to complaints that the Smart ED is underpowered, by pointing to limitations of getting enough power out of the 16 kWh Tesla pack used in the Smart ED.]

So even if other automakers move ahead of the pack in terms of battery technology and electric cars, you think everybody will eventually be in the same place?

Maybe not everybody, but those who are serious about it. Daimler will have the opportunity be there on time.

We had the same story, the same hype, in California in the 1990s, and we all know what happened. This is not saying battery or fuel cell technology is a bad thing to do, but nobody can be faster than the laws of nature. We have to do thorough development, and we will come up with high numbers of cars, but this will take time. People have very high expectations in terms of quality and reliability of the car. There will be an increasing number of battery electric vehicles and fuel cell electric vehicles, but it won’t just jump from zero to 100,000 cars a year.

Source: Plugin Cars

SLS AMG E-CELL Electric Super Sportscar Slated for Production in 2013

SLS AMG E-CELL Click to enlarge.

Mercedes-AMG plans to begin production of the SLS AMG E-CELL electric super sportscar in 2013, said Dr. Dieter Zetsche, Chairman of the Board of Management of Daimler AG during the company’s press conference at the North American International Auto Show. Mercedes first announced development of the electric gull-wing sportscar in July 2009.

The four synchronous electric motors in the SLS AMG E-CELL deliver a combined 525 hp (392 kW) of power and 649 lb-ft (880 N·m) of torque. The four compact electric motors each achieve a maximum rpm of 12,000/rpm and are positioned close to the wheels, substantially reducing unsprung masses compared with wheel-hub motors. One transmission per axle transmits the power.

The race for the best super sportscar with electric drive is on.

—Dieter Zetsche

The SLS AMG E-CELL drive features a liquid-cooled, high-voltage lithium-ion modular battery pack with an energy content of 48 kWh and a capacity of 40 Ah. The maximum electric load potential of the battery, which consists of 324 lithium-ion polymer cells, is 480 kW. One of the technical bases of this performance is the intelligent parallel switching of the individual battery modules, which also helps to maximize the safety, reliability and service life of the battery, according to the company. The 400-volt battery is charged using targeted recuperation during braking.

The incorporation of the electric drive components required no changes whatsoever to car’s weight-optimized aluminum spaceframe. Click to enlarge.

The electric-only drive system was factored into the SLS development process at the concept phase. Its packaging is designed for the integration of the high-performance, zero-emissions technology, enabling the four electric motors and two transmission units to be positioned as close to the four wheels as possible and very low down in the vehicle.

The same applies to the modular high-voltage battery—its component parts are located in front of the firewall, in the center tunnel and behind the seats. Benefits of this solution include the vehicle's low center of gravity and balanced weight distribution—ideal conditions for optimum handling, and something the electric-drive SLS AMG shares with its gasoline sibling.

The additional drive to the front wheels necessitated a new front axle design. Unlike the series production vehicle with the AMG V8 engine, which has double wishbone suspension, the SLS AMG E-CELL features an independent multi-link suspension with pushrod damper struts. This is because the vertically-mounted damper struts in the series-production SLS had to make way for the additional drive shafts. Frequently found in racing cars, the new horizontal damper units are actuated via separate pushrods and transfer levers.

Another distinguishing feature is the speed-sensitive, rack-and-pinion power steering, with the power assistance operated by electro-hydraulics rather than conventional hydraulics.

The braking system on the prototype features AMG ceramic two-piece brakes, available as an optional extra on the series production model. It delivers extremely short stopping distances, a precise actuation point and outstanding fade resistance, even under extreme operating conditions. The generously dimensioned, radially floating rotors measure 15.83 x 1.54 inches at the front and 14.17 x 1.26 inches at the rear and are made of carbon fiber reinforced ceramic composite material connected to aluminum hubs.

The ceramic brake discs are 40% lighter than the conventional, gray cast iron brake discs. This reduction in unsprung mass improves not only handling dynamics and agility, but also ride comfort and grip. The lower rotating masses on the front axle also ensure a more direct steering response—which is especially effective in high-speed cornering. The ABS and ESP systems have been adapted to match the particular operating spectrum of the permanent all-wheel drive.

Source: Green Car Congress

Mercedes-AMG Provides Additional Details on Progress of SLS AMG E-CELL Electric Super Sports Car

This is a very cool car with a battery pack nearly the size of Tesla's Roadster. Unfortunately, the price tag will likely be just as cost prohibitive to "average" car buyer.

Source: Green Car Congress:

The Mercedes-AMG SLS AMG E-CELL. Click to enlarge.

Mercedes-AMG, the performance brand within Mercedes-Benz Cars, provided an update on its development of an electric version of the SLS AMG, the development of which it announced last July.

With a power output of 392 kW (526 hp) and 880 N·m (649 lb-ft) of torque, the gullwing with electric drive is part of the company strategy entitled “AMG Performance 2015” which aims to continually reduce fuel consumption and emissions. The SLS AMG E-CELL may see a limited production run, the company says.

Traction is provided by four synchronous electric motors each achieving a maximum 12,000/rpm and positioned near to the wheels. Compared with wheel-hub motors the unsprung masses are substantially reduced. One transmission per axle transmits the power.

Powertrain components of the E-CELL. Click to enlarge.

The electric model accelerates from zero to 100 km/h in 4 seconds—which almost puts it on the same high level as the SLS AMG with 6.3-liter V8 engine developing 420 kW (571 hp), which can accelerate to 100 km/h in 3.8 seconds. However, unlike the combustion engine, torque build-up with an electric motor is instantaneous—maximum torque is available virtually from a standstill.

The SLS AMG E-CELL drive incorporates a liquid-cooled high-voltage lithium-ion battery featuring a modular design with an energy content of 48 kWh and a capacity of 40 Ah. The maximum electric load potential of the battery, which consists of 324 lithium-ion polymer cells, is 480 kW.

The intelligent parallel circuit of the individual battery modules helps to maximize the safety, reliability and service life of the battery. The 400-volt battery is also charged by means of targeted recuperation during braking while the car is being driven.

A high-performance electronic control system converts the direct current from the high-voltage battery into three-phase alternating current which is required for the synchronous motors and regulates the energy flow for all operating conditions. Two low-temperature cooling circuits ensure that the four electric motors and the power electronics are maintained at an even operating temperature.

Another perspective on Mercedes-Benz SLS AMG E-CELL powertrain components. Click to enlarge.

A separate low-temperature circuit is responsible for cooling the high-voltage lithium-ion battery. In low external temperatures, the battery is quickly brought up to operating temperature with the aid of an electric heating element. This helps to preserve the overall service life of the battery. In extremely high external temperatures, the cooling circuit for the battery can be additionally boosted with the aid of the air conditioning system.

Battery pack modules are located in front of the firewall, in the center tunnel and behind the seats. Advantages of this solution include the vehicle’s low centre of gravity and balanced weight distribution. The installation of the drive components required no changes to the model’s weight-optimized aluminium spaceframe.

The additional front-wheel drive called for a newly designed front axle: unlike the series production vehicle with AMG V8 engine, which has a double wishbone axle, the SLS AMG E-CELL features an independent multilink suspension with pushrod damper struts. This is because the vertically-arranged damper struts in the series SLS had to make way for the additional drive shafts. As is usual in a wide variety of racing vehicles, horizontal damper struts are now used, which are operated via separate push rods and transfer levers.

This front-axle design, already tried and tested in motorsport, enables the agility and driving dynamics of the electrically-powered SLS AMG to attain the same high levels as the V8 variant. Another feature is the speed-sensitive power steering with rack-and-pinion steering gear: the power assistance is implemented electrohydraulically rather than just hydraulically.

The technology vehicle is slowed with the aid of AMG ceramic composite brakes, available as an optional extra for the series production model, which feature extremely short stopping distances, a precise actuation point and outstanding fade resistance, even in extreme operating conditions.

The over-sized discs—measuring 402 x 39 mm at the front and 360 x 32 mm at the rear—are made of carbon fibre-strengthened ceramic, feature an integral design all round and are connected to an aluminium bowl in a radially floating arrangement.

The ceramic brake discs are 40% lighter in weight than the conventional, grey cast iron brake discs. The reduction in unsprung masses not only improves handling dynamics and agility, but also ride comfort and tire grip. The lower rotating masses at the front axle also ensure a more direct steering response—particularly noticeable when taking highway bends at high speed. The ABS and ESP systems have been adapted to match the special application spectrum of the permanent all-wheel drive.

The air outlet openings on the hood and the vehicle sides have been modified for enhanced aerodynamics. The front apron has not only been brought further forward, but also helps to guarantee an optimized airflow in the area of the underbody. This improves air resistance while reducing downforce.

An extendable front splitter enhances this effect: in parallel with the automatic rear spoiler, it extends downwards by seven centimeters at speeds above 120 km/h (75 mph) and helps to further accelerate the air which travels beneath the car. When it reaches the area of the rear axle, the air enters the rear diffusor which, due to the lack of an exhaust system, features a steeper angle, thus increasing downforce at the rear axle and in turn further enhancing the aerodynamic balance.

The AMG instrument cluster and center console both feature a new design. The new AMG instrument cluster provides information on speed, charge status of the battery and the estimated range. The newly designed center console now houses a 25 cm touchscreen, which driver and passenger can use to conveniently operate all of the audio, climate and navigation functions, and also obtain information on the flow of power from the four electric motors.

The AMG Drive Unit, which is angled towards the driver, houses buttons for starting the motor, and the ESP functions, the AMG memory function and the extendable front splitter and rear spoiler. Using three new buttons, the driver can switch simply between P, R and D. The park setting is also enabled automatically by switching the electric motors off.