A new study has found intelligent battery management and various measures, including temperature, avoiding regular high charging and frequent discharging to 0% can lead to a considerable improvement in EV battery lifespans and residual value.
The actual lifespan has long been discussed. The many misconceptions has led the German consulting P3 Group to publish a study into the ageing of EV batteries and which factors could contribute to a better energy and resource management.
State of health (SoH), gross capacity and net capacity all play a part. The study found the potential of EV batteries (lithium-ion and LFP) is also very dependent on temperature (ideally 20–25 oC). High temperatures will significantly affect the battery lifetime, it said. EVs should be left in a 10–50% SoH when not used for a long period of time, it said.
To evaluate the capacity of EV batteries of different ages, P3 first conducted a study of 50 vehicles and later of 7,000 cars together with Aviloo, a leading battery diagnostics company.
Earlier estimations of SoH values were theoretical. The field tests revealed the degradation curve of the battery capacity showed an acceleration up to 30,000km. After that, the degradation was almost linear, even up to 2–300,000km, it said. SoH values were > 80%.
The battery anode first creates a solid electrolyte interphase layer, which reduces battery capacity. After stabilisation of this layer, the degradation will slow down, according to the study.
Regular high charging power will reduce the SoH values considerably, while a single high effect charge has no significance, it said. Frequent discharging to 0% and charging to 100% will also reduce predicted lifespans, it stated. Moderate driving styles will extend the battery life: fast acceleration or long high-speed motorway driving will reduce SoH values, it said.
P3 operates with three concepts: end of warranty, end of first life and end of second life. Most EV batteries can be used for other purposes even when the SoH value falls below 70%. The residual financial value will be around 40% after being used in an EV (up to 12 years). After 12–20 years, they can go into battery energy storage systems and grid balancing. The valuable battery raw materials lithium, nickel and copper can be recycled.
In conclusion, P3 and Aviloo said that intelligent battery management and the above-mentioned measures can lead to a considerable improvement of the EV battery lifespan and a better resource economy.
