A longer battery life for electric buses

Researchers at BFH are engaged in a project for the development of an innovative electric bus. What is their mission?

The BFH research team is conducting a series of tests with batteries that will be used in a future electric bus from Carrosserie Hess AG. The main focus is on analysing the degradation and behaviour of the battery over a certain period of time.

Battery degradation is a natural process in which the battery loses storage capacity over time. The researchers want to use the data obtained from the tests to develop a degradation model that optimises the battery’s service life. They are also working on a charging process that will enable real-time battery capacity estimation.

What unique expertise can the researchers contribute to the project?

The researchers have extensive expertise in all aspects of batteries, in particular in electrochemical phenomena in the context of battery degradation. Thanks to their knowledge, they can analyse and predict the performance of a battery with great precision.

Over the years, they have developed various models that are tailored to these processes. This enables them to provide solutions to optimise battery service life and efficiency.

How did the researchers proceed?

They divided their work into three main tasks:

• Firstly, the planning and monitoring of battery tests to ensure seamless execution, as batteries can pose a safety risk if handled improperly.

• Secondly, the integration of the test data into a self-developed model that is aligned with the tested battery.

• Thirdly, the development of algorithms that can accurately predict battery condition, even with short charging times.

What insights have been gained so far?

The primary outcome of the project is the “Swiss eBus Plus”, an electric bus developed by Carrosserie Hess AG. This electric bus will be equipped with a battery degradation model and an optimal control algorithm to ensure that the battery operates under the best possible conditions.

The algorithm will also be integrated into the heating system and the overhead wires to improve the overall performance and efficiency of the vehicle.

What are the major challenges facing the project?

The biggest challenge lies in the behaviour of the battery cell and stems from its specific chemistry. The aim of the project is to maximise the use of the battery and at the same time optimise its service life.

Achieving this balance is crucial to the success of the electric bus, since the battery is a major source of expense in electric vehicles. Because of the short service life of batteries, running electric vehicles is more expensive.

How does the project benefit society?

The project promotes the electrification of local public transport and represents a significant step towards a climate-friendly future with low greenhouse gas emissions. It is crucial to initiate this change now. Every bus with a combustion engine purchased now will be in use for 15 to 20 years and contribute to environmental pollution.

The replacement, preferably without delay, of diesel-powered buses with electric alternatives will contribute to a reduction of greenhouse gases and to the sustainable development of our society.

When will a powerful battery be available for public buses?

Remarkable progress has been made in battery technology over the past 20 years and further improvements can be expected thanks to ongoing research efforts. However, the transition from laboratory innovations to commercial use is as lengthy process.

Promising technologies such as solid-state batteries and lithium-sulphur batteries could be available for certain applications in five to seven years. They will not completely replace lithium-ion batteries in the near future, but they will at least be able to supplement them.