BMW i3 and power electronics

The BMW Group has debuted the series version of its electric vehicle BMW i3, simultaneously in New York, London and Beijing. The BMW i3, the group’s first pure electric series produced model, features a number of technological innovations, such as a carbon-fibre passenger cell and a chassis made of aluminium.

If desired, the BMW i3 is also available with a range extender, which maintains the charge of the lithium-ion battery at a constant level en route, as soon as it falls below a specified value. This is performed by a two-cylinder gasoline engine with 34 hp (25 kW), mounted adjacent to the electric motor above the rear axle. The range extender increases the car’s maximum range in day-to-day driving to around 300 kilometres.

With a curb weight of 1195 kg, the BMW i3 is said to be lighter than most vehicles in the compact segment, yet offers significantly more space for up to four occupants. Below are some key features.

Electric motor

The electric motor of the BMW i3 was designed for use in city traffic and provides 125 kW/170 hp with a torque of 250 Nm. The full torque, which is typical for electric motors, is immediately available from a standstill and does not need to be built up first via the engine speed, as is the case with combustion engines. The BMW i3 accelerates from 0 to 60 km/h in under 4 seconds and to 100 km/h in only 7.2 seconds (7.9 seconds in the version with range extender). 

Lithium-ion high-voltage battery

The energy supply for the drive, as well as all other vehicle functions, is provided by a specially developed lithium-ion high-voltage battery, which sets new standards in terms of energy efficiency. The intelligent heating/cooling system of the high-voltage battery ensures that energy performance (and thus the vehicle’s range) is less affected by temperature fluctuations than it normally is with batteries of this type. This makes a significant contribution to both the performance and service life of the cells. An eight-year warranty or 100,000 miles is given for the high-voltage battery (for 70% of the charging capacity). Via the supplied charging cable, the battery is already charged for 80% capacity in 6-8 hours (based on 16 A current). The charging duration can be reduced by approximately 30% with the optionally available Wallbox Pure.

Intelligent energy management

To allow for an optimal range in every driving situation, during the development of the BMW i3 particular emphasis was placed on low energy consumption of the electrical components. For example, the interior heating system is said to save up to 30% of electricity compared to a conventional electric-heating system. Energy-saving LEDs are used for the interior lighting and are also available as an option for the exterior lighting. In addition, the E-drive offers the possibility of braking via the accelerator pedal. If the driver takes his foot off the accelerator pedal, the electric motor assumes the function of a generator and feeds the energy gained from the motion of the wheels back into the high-voltage battery. This so-called energy recuperation generates a braking torque which leads to an effective deceleration of the vehicle and pays off in terms of energy savings for especially foresighted driving styles.

Charging the BMW i3

The BMW i3 can not only be charged at home using the wallbox or the charging cable, it can also be charged on the go from a continuously increasing number of official charging stations. The BMW i3 finds these easily via innovative BMW ConnectedDrive Services such as, for example, the fully networked BMW i Navigation with display of the dynamic range and charging stations.