BMW 325iX (1987–1990)
The "Electric car with high-energy battery" research project first launched in 1981 eventually led to eight BMW 325iX models being converted from all-wheel to front-wheel drive from 1987 onwards ready for testing. They served as experimental vehicles for trialling a brand-new, maintenance-free sodium-sulphur (NaS) battery, which had been purpose-developed by Asea Brown Boveri (ABB) for use in an electric vehicle. With an energy density three times greater than that of conventional lead-acid batteries it represented a great leap forward: for the first time there was a realistic prospect of mitigating the specific disadvantages of electric drive systems, such as battery weight and the space required. Beyond this, all of the electric drive components were to be tested out and further improved. BMW constructed a special test rig for this purpose with a built-in output calculator. An-other new feature was the electronic drive management, which regulated and monitored charging from the mains socket, the energy flow between motor and battery, as well as the system's thermal circuit.
The entire control electronics were housed in a compact component carrier next to the motor. The project management team resolved to conduct the first ever external trials under everyday conditions with the electrically powered BMW 3 Series. A BMW 3 Series Touring proved its suitability for daily use as a delivery vehicle for the German postal service, for instance, while other prototype models demonstrated their merit as city cars operated by state and local authorities. It was not least because of this that the test vehicles were equipped with a diesel-fuelled hot water system for heating the vehicle interior.
Motor DC shunt-wound motor (ABB)
Continuous/peak output 17 kW / 22 kW
Energy storage Sodium-sulphur high-energy battery
Capacity 22 kWh
Weight 265 kg
Top speed 100 km/h (62 mph)
Acceleration 0-50 km/h (31 mph) 9 sec
Range in city traffic 150 km (93 miles)
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