BMW ActiveE Concept (2010)

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The BMW Concept ActiveE electric car is based on the BMW 1-Series Coupe, and it's a full four-seater. That contrasts with the Mini E, whose back-seat space was largely taken up by the large lithium-ion battery pack.

In fact, says BMW, the passenger compartment is identical to that of a liquid-fueled 1-Series Coupe, with no changes in the head, leg, and shoulder space dimensions. The Concept ActiveE adds a few unique styling touches to what is recognizably a 1-Series Coupe, with a closed rear apron (no exhaust pipe!), aerodynamic alloy wheels, and blue accents including a blue ring in the tire sidewall. original article  read full article

BMW ActiveE Concept

BMW ActiveE Concept

Rear motor, rear-wheel-drive

The ActiveE is rear-wheel-drive, as are all BMW sedans, with a 125-kilowatt (170-horsepower) electric motor in the rear axle. Though the power electronics sitting on top of the electric motor reduce trunk volume, there's still 7 cubic feet of space in the trunk, which BMW notes is larger than that of the 1-Series convertible--making the Concept ActiveE clearly more practical than the electric Mini was.

Regenerative braking is integrated into the rear wheels, turning the electric motor into a generator when the driver lifts off the accelerator. BMW says up to 75 percent of all deceleration occurs without using the brakes, recapturing 20 percent of the battery's energy. When greater brake force is required, pressing the brake pedal engages the friction brakes just as in a standard BMW.

Jointly developed battery pack

The battery pack used in the BMW Concept ActiveE  is a joint effort among BMW, Bosch, and Samsung, which supplied the lithium-ion cells in a format specially made for automotive use. The Mini E, on the other hand, lashed together thousands of "commodity" small lithium cells, of the kind used in mobile phones and laptop computers.

The liquid-cooled pack is actually split among three locations: where the gasoline tank would sit under the rear seat, in the tunnel formerly occupied by a propeller shaft, and in the former engine compartment. Oddly, BMW does not specify the total energy capacity of the entire pack.

But the distributed pack preserves a 50-50 weight ratio, and the center of gravity in the concept is lower than in a gasoline- or diesel-fueled 1-Series. Total vehicle weight is about 3,900 pounds.

100-mile range

BMW promises an electric range of roughly 100 miles, and quotes a 0-to-62-mph time of 8.5 seconds. Maximum speed is limited to 90 miles per hour. Charging time is said to be 3 hours in Europe (using a 50-ampere circuit at 230/240 Volts), and about 4.5 hours in North America (on a 32-amp circuit providing the 220-Volt current used in electric stoves or clothes driers).
Like the Mini E, BMW plans to put real-world drivers behind the wheel of these emissions-free sports sedans. The goal is the same: to gather actual data on how drivers use electric cars in everyday travel. Recuperation of energy increases range.

In the purely electric powered BMW, the driver may control deceleration as well as acceleration through the movement of the accelerator pedal. As soon as the driver's foot is removed from the accelerator, the electric motor performs the function of a generator, converting the vehicle's kinetic energy into electric power and storing it in the battery pack. Intensive use of this so-called energy recuperation process by the motor increases the range by up to 20%.

At the same time, a brake torque is created which results in effective deceleration of the vehicle. This response enables a very comfortable driving style, especially at medium and constantly varying speeds. In urban traffic, some 75 percent of all deceleration manoeuvres are initiated without the need for the brake pedal. During Brake Energy Regeneration function, the vehicle's brake lights are illuminated.

This brake effect acts on the rear wheels only. When the driver requires a higher level of deceleration, stepping on the brake pedal engages the conventional hydraulic braking system. If an emergency braking maneuver is required during braking, the Dynamic Stability Control (DSC) system applies selective braking and motor management measures to ensure that safe braking is always guaranteed.

The brake system is fitted with an electric vacuum pump which is activated on demand. Along with the Electric Power Steering (EPS) familiar from the production models of the BMW 1-Series, these features contribute to an increase in the overall efficiency of the vehicle.

Innovative lithium-ion battery pack with its own liquid cooling.

The lithium-ion battery pack specially developed for this vehicle supplies energy to the motor and all other functions of the BMW ActiveE Concept. The high-voltage battery units offer a particularly high storage capacity and durability. For the first time, storage cells are used which were developed especially for use in automobiles by the BMW Group in collaboration with the co-operation partner SB LiMotive. Powerful battery cells are key when it comes to designing production vehicles with electric drive. Through the collaboration of the BMW Group with a joint venture of the companies Bosch and Samsung SDI [SB LiMotive], leading expertise in the area of battery technology and electro-mobility has been brought together. The aim is to use the best available technology in the area of energy storage as part of the development of the Megacity Vehicle.

For some time now, lithium-ion technology has demonstrated its particularly high storage capacity and deep-cycle resistance - for example in mobile phones and laptops. The technological expertise of SB LiMotive ensures that these properties are retained even under the special conditions of use in an automobile and the relevant demands in terms of durability, endurance and safety.

The lithium-ion batteries of the BMW ActiveE Concept have their own liquid cooling system and intelligent battery management system, which are key elements in increasing both the storage capacity and the durability of the battery cells. These systems also ensure that the long range can be maintained largely independent of external climatic conditions. The high storage capacity is the decisive factor in achieving as long a range as possible. The storage system developed for the BMW ActiveE Concept enables a real-world range of about 160 km / 100 miles on a single charge, depending on conditions (FTP72 cycle range is calculated to be 240 km / 150 miles in simulation).
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BMW ActiveE Concept (2010)

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This article was published on 2010/11/28