Mixing quick and conventional charging protects EV batteries

May 21, 2014 // By Paul Buckley
A combination of quick and conventional charging is ideal for electric vehicle battery performance is the conclusion of the RheinMobil electric mobility project after about 120,000 km of practical evaluation of electric vehicle operation.

The project has demonstrated that a controlled mix of quick and conventional charging ensures a high utilization rate of the vehicles and protects the battery and shows that interference-free charging is a major prerequisite for the economically efficient use of electric vehicles.

RheinMobil is a joint project of Michelin, Siemens, Karlsruhe Institute of Technology (KIT), the Fraunhofer Institute for Systems and Innovation Research ISI, and the mobility services company e-Motion Line (eML). The project is part of the 'LivingLab BWe mobil' electric mobility showcase funded by the Federal Republic of Germany.

RheinMobil is aimed at demonstrating that certain utilization profiles allow for an economically efficient operation of electric vehicles, with commuting and business traffic between Karlsruhe and the Alsace region being used as an example. Presently, six minibuses with seven seats each are commuting daily for Michelin, while Siemens operates a compact vehicle for business trips. Every month, each vehicle drives an average of about 3000 km.

“Since the start of the project last spring, we have found that conventional vehicles can be replaced by electric vehicles for both operation profiles. On the local level, we have already reduced CO2 emissions by eight tons,” Dr. Olaf Wollersheim, one of the two RheinMobil Project Heads at KIT, said. “Moreover, we realized in the winter months that weather and temperature fluctuations caused the energy consumption to increase, while the operability and availability of the vehicles were not affected,” Dr. Kevin Stella, who coordinates the project together with Wollersheim, added.

In the next step, utilization rate of the vehicles by Michelin is planned to be increased with several groups of commuters using every vehicle in accordance with the shift plan. In this way, the mileage will rise to several hundred kilometers per day. However, this will require quick charging that presently takes about 30 minutes, whereas conventional charging requires stop times of nine hours. The RheinMobil team wishes to show that electric vehicles