What is the impact of battery degradation on electric transportation?

Only a few years ago, electric trucking was widely regarded as impossible. Yet, we’ve witnessed the widespread adoption of electric mobility, including road freight, thanks to advances in several fields. One enabler is, of course, the progress in the field of electric energy storage.

In the mobility sector, this is largely synonymous with the development of Lithium-Ion batteries. There used to be different ways to store energy onboard a vehicle, and there will certainly be other solutions in the future, but for the time being, Li-Ion based systems have become the de-facto standard.

Li-Ion battery is an umbrella term for a wide range of different implementations. They differ in their design, chemical composition, mechanical form factor and, consequently, also their electrical properties. Each of these different types has its own advantages and disadvantages, and matching the right technology for the right application is a crucial part of designing a successful, battery-electric-based product.

They do, however, have one adverse characteristic in common that makes electrified transport fundamentally different from the trucking world that we have known so far: an electric vehicle's performance becomes worse over its service life. It’s not just about the familiar wear and tear from brakes, tires, clutches, etc., which are usually mitigated at a reasonable cost by visiting the service center. It’s rooted in a completely new challenge: battery degradation.

The truck operator will observe macroscopic effects like capacity loss or loss of power capability. Inside the battery cell, there are a multitude of different (electro)chemical processes, not just a single mechanism. These take place all the time; a completely unused battery will suffer degradation over time. In real-world applications, degradation is dominated by repeated charging and discharging, often referred to as "cycling".

A few factors directly influence the process. Battery degradation is heavily affected by battery temperature, charging/discharging currents and the state of charge (SOC) window in which the battery is cycled.

How to manage battery degradation

Some of these can already be addressed in the hardware design phase, for example through appropriate capacity sizing and well-designed thermal management, but others are up to the operator. Advanced planning and scheduling for both charging and the truck's routes must take into account different factors ranging from topography, weather, traffic and the boundary conditions set by the logistics application. These factors are often contradictory, and sophisticated modeling and optimization tools are required to find the most competitive and suitable solution.

At Einride, these aspects are addressed from multiple angles. It starts with the analysis of the customer case with machine learning-supported energy consumption models enabling very accurate predictions of a vehicle’s energy consumption. This allows Einride to find the optimal charging schedules and keep a vehicle within a healthy SOC range without charging at excessive currents.

With the best preventative measures, battery aging can be mitigated, but not avoided. It is imperative to track the degradation that has already occurred and to be able to predict the remaining life. Our models have to work with only the available temperature, voltage and current measurements that are transmitted through the telematics system. As mentioned above, the conditions under which a battery cycling event occurs determine its impact on battery life – quantifying this effect is the tricky part, which requires a large amount of knowledge and data on the respective battery systems.

The Einride team is continuously improving its methodology and working with OEMs to enhance the data collected from the vehicle with the help of our proprietary digital freight platform. With it, we can better forecast the remaining battery life, both for the operating scenario at hand and for the assessment of more pessimistic or more optimistic scenarios that can be implemented by changing the operating profile.

During operations, battery health has to be assessed with reasonable accuracy – together with the forecasting of the remaining lifetime, these pose huge challenges and opportunities in the domains of telematics, data science and modeling.

The effort is greatly rewarded. Replacing a battery is, in most cases, not an option with the battery being the single most expensive part of an electric truck – depending on its size, it can make up 30-50% of the vehicle cost. A broken battery constitutes, more often than not, a total loss of the vehicle.

Equally important, battery manufacturing requires a lot of energy and resources, and it contributes the largest share of greenhouse gas emissions of any vehicle component. Every investment in battery analytics and management has a positive impact not only on the cost of operations but also on the ecological balance sheet of the electric truck.

Christoph Futter

Battery Operations Director at Einride