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Siemens and BMW developing flexible rapid charging system for plug-ins that can use AC or DC

Siemens charging station and BMW ActiveE demonstrating the new flexible charging system. Click to enlarge.

Siemens and BMW are developing a flexible rapid charging system to make it possible to use the same socket to charge up electric cars on either direct current (DC) or alternating current (AC). The work is part of the Modellregion Elektromobilität München – Drive eCharged project being funded by Germany’s Ministry of Transport, Building, and Urban Development.

Siemens says the new system was successfully tested in September 2011 with a Siemens charging station and a BMW ActiveE vehicle, and Siemens and BMW have already submitted proposals for standardizing DC charging to the International Electrotechnical Commission (IEC). (Earlier post.) The two companies are planning to continue this work on standardization.

The system utilizes plugs standardized for AC charging that have been modified to accommodate DC rapid charging. Until now, electric vehicles that can be charged with either AC or DC needed to use two different sockets. The project partners recently presented a prototype of the new charging system in the Transportation section of the Deutsches Museum in Munich.

Charging times and vehicle range are key aspects that influence consumer acceptance of electric cars. Today’s batteries have to be recharged more often than a conventional vehicle needs to be refueled, and the recharging process also takes several hours when a conventional socket is used. Charging times of half an hour or less can be achieved with DC technology, however, Siemens notes.

Unlike AC systems, with DC technology the power converter is located outside the vehicle at the charging station, which means the cars that use it can be made lighter. This, in turn, increases vehicle range, and combined with short charging times it therefore makes electric vehicles more attractive to fleet operators. Special charging units are required for this system, however, which is why the Drive eCharged partners developed the flexible approach that offers several advantages over the systems now in use.

For example, AC and DC plugs fit into the same socket on the vehicle. The new approach also standardizes communication between the vehicle and charging station for AC and DC operations, which means it will be able to support additional functions like smart charging or bi-directional charging for both charging modes in the future. Over the medium term, it is expected that DC systems will be able to charge a vehicle to the equivalent of a 100-kilometer (62 mile) range in just 15 minutes.

Siemens is also working with BMW on an inductive charging system.


Henry Gibson

Most compact fluorescent lamps and some desktop computer power supplies and other power converters for electronics can be operated on direct current.

A simple voltage divider of two small series incandescent lamps with three terminals can be used to operate low voltage CFL bulbs connected pair at a time as a three terminal device to a PRIUS battery in japan and the US. Some higher voltage CFLs may be directly connected alone to the battery. The prius can be operated in a mode that keeps the battery charged with intermittent engine operation while stationary.

Simple lightweight buck-boost regulators could be built into any car to connect to a large battery for quick charging. This was demonstrated by Ron Gremban of Calcars several years ago. ..HG..


Henry Gibson, your comment is both off topic and useless. Just because it is possible to jury rig a series of incandescence and cfl light bulbs from a battery is no reason to do this, and encouraging people to do this is dangerous.

As for your second paragraph, yes again this is possible, but the article states that doing it this way is uneconomical, that external high power converters in a relative few number of charge stations is better than every car having it's own, both from a cost and weight perspective.


This is the most sensible approach to car charging I have read. I really hope this becomes an international standard to benefit all the EV drivers in the world.

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