In 1981, BMW launched the "Electric car with high energy battery" research project. The goal is to develop an alternative to lead battery that prevailed until then. Indeed, as we already knew in 1980, this was only suitable for a limited extent to use in an electric car with its high weight and low energy density. The research is set up to experiment with a new Sodium-Soufre (NAS) mainly developed specially developed by ASEA Brown Boveri (ABB) for electric cars. Its energy flow density represents the triple of that of traditional lead batteries: significant progress insofar as for the first time, it is possible to consider reducing the drawbacks specific to electric motors that are weight and weight and Battery clutter, and BMW also created a test bench specially dedicated to electric motors with an integrated power calculator. Development was divided: in parallel with batteries' developments, optimization of control systems and transmissions has become more and more important.
But it takes six years for the research project to produce the first results. Then the first of eight electric vehicles based on the BMW 325iX of the E30 series will hit the road. However, the all-wheel-drive three-series, which is the basis of the research vehicle, is pretty much sterilized. The developers convert the all-wheel-drive vehicle to front-wheel drive, which is not typical for BMW, and install a somewhat weak DC shunt machine with only 22 kW of power, almost 220 pounds less than the old batteries used in the 1602e (the first BMW in 1969 and the LS in 1975 to be electric). In comparison, in the base vehicle, the inline six-cylinder engine was allowed to produce up to 125 kW.
While the leap in battery technology was significant, the automaker used a relatively modest 30-hp electric motor that could only propel these prototypes to 31 MPH in 9 seconds.
However, these examples did have a significant range of 93 miles. Adding another note to this part of BMW’s history, these EV prototypes marked the first times the automaker conducted external testing in everyday conditions. The E-Kombi model proved to be perfectly suited for the Bundespost (German postal service), while other prototypes were used throughout the city by state and local authorities.
So why are NaS batteries no longer used today, despite their good energy density? It’s due to their operating temperature. The NaS battery only works at temperatures above 300 degrees Celsius and therefore needs to be heated constantly. This is a decisive disadvantage when used in automobiles.
Still, the ideas from the 325iX helped shape the future of electric mobility, laying the foundation for the advanced electric vehicles produced today.
But this was not BMW's first attempt since in 1972 for the Munich Olympic Games, BMW presented the 1602e, a story that we tell you here.
Then BMW will continue to release a few more prototypes over time.
Comments