|BMW ActiveE. Click to enlarge.|
The BMW ActiveE (earlier post) will be available for lease in the metropolitan markets of Los Angeles, San Diego, San Francisco, Sacramento, New York and Boston as well as the state of Connecticut beginning in Fall 2011 for $499 per month for 24 months with a down payment $2,250.
The BMW ActiveE is the BMW Group’s next step towards a mass-produced electric vehicle. Within the framework of project i, the BMW Group is carrying out research and development work on the development of electrically powered vehicles. The ultimate goal is the concept of a Megacity Vehicle (MCV) that meets the demands of a sustainable mobility solution for congested urban areas. (Earlier post.) The drive components and battery technology that will be used in the MCV are being tested in the BMW ActiveE.
Beginning in 2011 in the US, Europe and China, a test fleet of more than 1,000 BMW ActiveE vehicles, produced at BMW’s Leipzig plant, will provide further insights into the everyday use of the vehicle. The findings will serve to deepen the knowledge already gained on the everyday use of electric vehicles and to learn more about customer requirements. The feedback from customers testing the MINI E and the BMW ActiveE will be fed directly into series production of the MCV, which the BMW Group will be launching under a new sub-brand in 2013.
The BMW ActiveE is based on the BMW 1 Series Coupe. The maximum power output of the electric drive system is 170 hp (127 kW) while maximum torque of 184 lb-ft (249 N&iddot;m) is available from a standstill, as is typical of electric vehicles and it remains available across an exceptionally broad load range. As a result, the BMW ActiveE accelerates from 0 to 60 mph in under nine seconds. Top speed is electronically limited at around 90 mph.
The permanent-magnet synchronous motor and the power electronics of the BMW ActiveE were developed entirely in-house. The entire power pack, including power electronics and transmission with differential, is integrated into the modified rear-axle support of the BMW ActiveE, and with 170 horsepower, still has a total weight of only around 200 lbs (91 kg).
The driving experience of the BMW ActiveE is enhanced by the possibility of slowing down using the accelerator pedal via brake energy regeneration. When the driver lifts off the accelerator pedal, the electric motor becomes a generator that feeds the electricity gained from kinetic energy back into the vehicle battery. At the same time, braking torque is created, which effectively slows the vehicle down. In this way, the accelerator pedal becomes a “drive pedal”. In urban traffic around 75% of all deceleration can be accomplished without using the brake pedal at all. Intensive use of this recuperation of energy via the motor also results in a range increase of up to 20%. Only when the driver wishes to slow down faster by stepping on the brake pedal does the conventional braking system of the BMW ActiveE come into play.
Unlike the MINI E, the BMW ActiveE features a distinctive “intermediate position” of the accelerator pedal, allowing the vehicle to “glide”. As a result, the vehicle does not immediately recuperate when the driver decelerates, but “de-clutches” using the electric motor’s zero momentum control, thereby utilizing its own kinetic energy to move forward. The BMW ActiveE then “glides” along the road without using energy. Gliding offers a most convenient way of increasing the vehicle’s range.
When the driver lets off the accelerator pedal to slow down, the regenerative brake torque only works on the rear wheels. Therefore the BMW ActiveE features an adapted drive-active vehicle dynamics interface, “Stability Management for Regeneration”, in order to also ensure vehicle stability during recuperation. The Dynamic Stability Control system has been adapted to the specific characteristics of the electric drive train. Based on various parameters, Stability Management for Regeneration adapts the recuperation level to each driving situation, combining the highest level of recuperation with best possible vehicle stability when decelerating in any situation.
Should a situation arise that is critical for vehicle stability when using recuperative or hydraulic brakes, the optimized DSC function ensures constant vehicle stability by means of targeted intervention into the braking system and engine management. Furthermore, DCS ensures that the rear wheels are able to convert the high torque of the electric drive into maximum propulsion when starting off.
The BMW ActiveE features large-format Li-ion storage cells, which are being used for the first time and were jointly developed by the BMW Group and its associate partner SB LiMotive exclusively for automotive use.
With the BMW ActiveE developers are testing the storage cells and the storage electronics, which are to be installed later in the MCV. The large battery unit of the BMW ActiveE takes up the space in the lower area of the vehicle normally intended for the drivetrain in a conventional vehicle. In order to accommodate additional storage cells, the space at the rear that has become available through the omission of a fuel tank is also utilized. Further lithium-ion cells are located at the front end in front of the cowl.
The BMW ActiveE’s three large storage modules are each protected by a specially-constructed steel-plate battery housing with integrated liquid cooling system. The cooling system constantly maintains the ideal operating temperature of the batteries, thereby contributing to an increase in the service capability and lifespan of the battery cells. The air conditioning/heating system tempers the liquid running through the storage unit housing via a heat exchanger. When connected to the electrical grid, the liquid can also be heated in order to bring the energy storage units up to the ideal temperature of approximately 70° Fahrenheit.
The BMW ActiveE achieves a range of approximately 100 miles (161 km) with a full battery charge. Intelligent battery management especially developed for the BMW ActiveE ensures that this range can be achieved as far as possible independent of external climatic conditions.
The lithium-ion battery units featured in the BMW ActiveE can be recharged from multiple external power sources. In addition to using the wallbox, a 32-ampere charging dock installed at the user’s home, the driver can also connect the vehicle to a conventional power socket or a publicly accessible charging station. The standardized SAE J1772 charging port on the vehicle ensures compatibility with most charging stations.
The battery can be fully charged within four to five hours using the wallbox at 32 amperes. A range of around 25 miles is possible after just a one-hour charge at the wallbox.
Unlike the MINI E, the BMW ActiveE offers the user the potential to cool or heat both the batteries and the car interior using intelligent preconditioning when the vehicle is connected to the grid, thus bringing them up to the ideal operating temperature even before setting off. A preconditioned vehicle offers two advantages: first, the ideal operating temperature of the batteries guarantee highest possible power output and ensure a longer range. Secondly, the interior is already adjusted to a pleasant temperature prior to starting a journey both in the summer and the winter.
Intelligent preconditioning of the BMW ActiveE automatically determines according to the ambient temperature to what extent the vehicle and the battery should be pre-cooled or heated.
Using the BMW MyRemote application, preconditioning can be activated directly or the user can determine via the timer when preconditioning should start. For instance, he or she can ensure that the vehicle is pre-cooled or heated in the mornings before they use the car. However, it is only possible to precondition the car if it is connected to a charging terminal. This ensures that the vehicle’s range is not shortened by preconditioning, on the contrary, it actually increases it.
The BMW ActiveE makes its North American debut at the New York International Auto Show and takes to the road beginning in Fall 2011.