While it seems like BMW is struggling a bit with its polar bear saving "i" sub-brand, it is worth knowing that they started experimenting with electric power around the same time Subaru introduced it's first all-wheel drive car.
That's right, BMW has been in the electric car game for way longer than you might think. Here is how they got to where they are today.
The story began at the 1972 Summer Olympics in Munich. While BMW stole the show with Paul Bracq's wonderful Turbo Concept supercar, they also prepared two electric coupes converted from BMW 1602s. These served as a means of transport for the members of the organizing committee, with some occasional camera-car duties as well.
Still, electric vehicles with lead batteries weighing 772 pounds and providing a range of only 37 miles were not something the Bavarians would have put into production. On the other hand, forty years on, the i3 is something they are, so let's see how they got to this 170 hp electric milestone.
BMW started the development of two electric cars in 1969. They wanted to see if an electric drive unit was suitable for the demands of everyday driving. In these special 1602s, the four-speed manual transmissions were replaced by a single Bosch DC shunt-wound motor with a peak output of 32 kW (while continuous power was a much more conservative 12 kW).
Intermediate gearing was used, while the traditional rear-wheel drive set up remained. The electric motor itself was 187 pounds, but that was nothing compared to the twelve standard Varta lead-acid batteries in the engine bay, weighting 772 lbs. With a top speed of 62 mph and an urban range of 19 miles even with the clever usage of regenerative braking, the 1602 Electric was far from being perfect.
BMW soon realized that an advance in battery technology was needed for future success.
In the summer of 1975, BMW secretly launched a new development prototype.
They used a discarded BMW 700 (LS) as a base, powered by a new DC series motor from Bosch. 10 Varta lead-acid batteries went to the engine bay, which were using centralized water topping up and degassing technology for easier maintenance. While weight was still an issue, this car also featured a brand new charger system, meaning that it could be plugged into household (230V) sockets that would charge it fully in 14 hours.
The car's drum brakes had an easy job as regenerative braking was used as standard, with the regular brakes only acting as backups. With the top speed of 40 mph, the range was less than 19 miles. On the plus side, it had a heated windshield and rear window.
In 1981, BMW started its "Electric car with high-energy battery" research project, which led to eight BMW 325iXs being converted from all-wheel drive to front-wheel drive. Their main objective was to test the brand new (and maintenance-free) sodium-sulphur (NaS) batteries, which had been purpose-developed by Asea Brown Boveri with electric vehicles in mind.
Since these had three times greater energy density than the conventional lead-acid batteries, this was a big step towards neutralizing the disadvantages of normal electric drive systems. BMW also started using electronic drive management software in order to monitor the power charging from the mains socket, the energy flow between motor and battery, and most importantly: the massive heat.
The first ever external trials were carried out by the German postal services, after BMW gave them 3 Series Tourings. With the range of 93 miles, they just about did the job.
With the promising results provided by the NaS batteries, BMW Technik GmbH was commissioned to design an electric vehicle from scratch. The new model had to be comfortable for four adults, with reasonable range and practicality for the urban environment. A high level of safety was also on the list, while engineers had to save weight in order to balance out the batteries as well.
It only took them 10 months to finish, and the E1 prototype was presented at the 1991 Frankfurt Motor Show. The chassis and some panels were made of high-strength aluminium, while the body was mostly of recyclable plastic. The battery pack was secured at a safety frame underneath the rear seats, while the electric motor — which was developed in-house — was integrated in the rear axle together with the transmission. With a range of 93 miles and a top speed of 75 mph, the E1 has proven itself as a full on city car.
Next year, the E2 was unveiled at the Los Angeles Auto Show. It was basically an E1 redesigned with the American market in mind. However by 1993, a more advanced prototype was ready using sodium-nickel chloride batteries, further boosting performance.
New technologies emerging in the early nineties meant that the new 3 Series could be turned into a proper electric car without too much of a hassle, as the electric motor now weighed just 65 kilograms including the transmission.
BMW made 25 experimental vehicles, eight of which took part in the world's largest ever public field trial staged on the German island of Rügen. The German Federal Ministry of Research and Technology was also supporting the project, while six cars went into the fleet of the Bavarian State Government. The cars were powered by rotating-field AC motors producing 32-45 kW. Since there were some issues with the sodium-sulphur batteries, BMW switched back to the sodium-nickel chloride technology which was used in the E1.
One car even got nickel-cadmium batteries, just to keep things exciting. With the range of 93 miles, and the top speed of 84 mph, these 3 Series models were almost there...
A massive fleet of electric Minis were given to select private and corporate customers in 2008, who probably enjoyed the benefits of zero emissions in the large cities of the United States and Europe. These compacts were powered by 150 kW asynchronous motors getting the juice from lithium-ion battery packs.
That was good for a very green 8.5 sec sprint to 62 mph, while the top speed went up to 94 mph. Range was not an issue in the cities, as the Mini E could do 155 miles with a full charge. Special chargers also came with the cars, which could top it up using standard sockets in two-and-a-half hours. That is something they would call trendigen. With this project, BMW's fleet of fully electric cars went past 600 members.
The BMW Concept ActiveE is a test bed for the brands future Megacity Vehicle, which we now can simply call the i3. More than a thousand electric cars were put into service based on the 1 Series, delivering an output of 125 kW and maximum torque of 184 lb-ft.
A brand new lithium-ion battery pack gave these cars a hundred mile range, while the 90 mph top speed meant that drivers could use the passing lane on a highway as well. Technical progress in the last five years was mind blowing, with the forthcoming BMW i3's electric drive system using 40% less space than the Mini E's, while delivering superior performance. Still, when it goes to production, the i3 will also have a range-extending diesel engine, just to be safe.
Photo Credit: BMW AG