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Many in the electric vehicle (EV) industry worry about upcoming environmental, social, and governance (ESG) policies that several governments plan to introduce for batteries as they become increasingly prevalent in our transition to clean energy and mobility. This legislature will pose ambitious lifespan requirements on electric vehicles - and especially on the batteries.
As government policies take form, there are uncertainties about how battery lifetime can be monitored, including:
So, what exactly is happening on the regulatory side?
One major market that has already passed ESG regulations for electric vehicles is the State of California. On August 25, 2022, the California Air Resources Board (CARB) introduced warranty requirements for EVs as well as for the battery pack itself. It specifies beginning in 2026 that, battery packs must maintain 70% of their storable energy content for eight years or a range of 100,000 miles (roughly 160,000 km). The requirements are tightened to 75% remaining energy from model year 2031 onwards.
And although the upcoming United Nations Global Technical Regulation (UN GTR II) is still under discussion, the initial draft specifies a remaining energy content of 80% after five years of operation or about 62,000 miles (100,000 km), as well as 70% remaining energy after eight years or 100,000 miles (160,000 km).
What all these regulatory policies have in common are battery lifespans of eight to ten years. As a battery system expert specializing in electric vehicles, I can tell you these are not modest lifetime targets to achieve.
It can be challenging to achieve the lifespan requirements, for example, when batteries are operated under extreme conditions, such as in hot or cold climates. They age faster – as explained in the Guide to Battery Aging article. Aging also accelerates when the vehicle is parked at high states of charge for long durations and when the battery is fast-charged. In conclusion, the lifetime of the battery is influenced by the EV user’s habits to a notable extent. EV users will need to understand how to operate EVs in a way that prolongs battery life, potentially modify their habits or daily routines, or require extensive maintenance for the battery.
So how can we estimate and track the aging of the battery systems to inform EV users?
Regular visits to the auto repair shop for maintenance are already commonplace for “traditional” combustion engine vehicles. Therefore, the straightforward solution is to take a similar approach, requiring the user to check their electric vehicle regularly and measure the aging of the battery pack.
But, for EVs, these battery aging check-ups are expensive, take a long time to perform, and require many resources to run. No one wants to wait for days while their car is tested.
This is where the European Union’s (EU) Battery Digital Passport comes in. It stipulates wireless monitoring to evaluate aging while the battery is used. The exact type of monitoring is not specified, leaving a lot of room for interpretation - and uncertainty. But, if set up correctly, it has the potential to make “traditional” check-ups obsolete. And it will be applicable in all European countries from 2024 onwards.
So, what is the EU Battery Passport all about?
While currently under negotiations, the Battery Passport is slated to be a digital record of information about the entire battery lifecycle – from production to recycling – including environmental impact and expected lifespan and durability of the battery. At this point , negations seem to focus on having the passport include:
The Passport is one aspect within a battery-focused directive to make batteries more sustainable. Some of the other aspects propose setting thresholds for batteries' carbon footprint and recyclability. Other aspects touch upon making batteries “second-life ready” and address the safety of stationary battery systems. The entire mandate is part of the EU’s Green Deal policy in response to climate change.1,2
The directive itself is still under discussion, but it already provides insight into the upcoming EV requirements that may need to be fulfilled by the battery systems. Here’s what we know:
Now, we have data on the one side, and we have ambitious safety, performance, and lifespan requirements on the other side. So, how do we make ends meet?
With relatively low costs, cloud-based monitoring can enable battery analytics software to evaluate entire fleets of EV batteries using the data that’s already produced by the on-board battery management systems (BMS). Every lithium-ion battery system comes with a BMS, so the data is readily available and straightforward to collect.
Cloud-based monitoring and battery analytics can reduce the number of visits to the auto shop for EV owners. Analytics can, for example, accurately estimate current battery health, safety and performance, as well as forecast battery aging. The analyses can be done online so there’s no need to drive to the shop.
Let’s have a look at battery analytics and state of health (SOH) forecasting, an example sketched out in figure 1. State of health indicates the level of degradation and remaining capacity of the battery, exactly what the government ESG regulations aim to improve and what the EU Battery Passport proposes to track.
Analytics start with operational data because this is the best foundation to understand what is happening inside the battery while it’s used. The data can be raw time-series (also known as time-stamped) data or preprocessed data, such as the performance and durability parameters that will be defined in the EU’s Battery Passport and other government initiatives.
The operational data from the battery management systems can be leveraged to serve two purposes:
If these characteristics are tracked over an entire fleet, there will be plenty of information on how different usage patterns influence the aging and lifespan of the batteries. For instance, operating an EV in a cooler climate will influence battery aging in a different way than operating an EV in a warmer climate. Similarly, commuters in cities with heavy traffic or who drive long distances may stress the battery differently than someone who rarely drives their EV.
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Complex chemical reactions happen inside lithium-ion batteries. To predict how batteries will perform or age in the future, experts use advanced modeling techniques paired with lots of computing power for big data – far beyond what any BMS system can handle.
On top of the chemical reactions inside the batteries, the individual usage patterns as well as operating and charging conditions add complexity. All operational information needs to be combined in an aging model that considers the crucial aging mechanisms of the battery and extracts all the relevant correlations to the usage patterns. Experts call this a “model-based” approach, setting up a set of rules or mathematical equations the model will use to make aging predictions.
Once the model has been developed, it can accurately predict how the battery’s state of health will change in the future, given a set of operating conditions. Auto manufacturers can then use this information to track whether the battery will meet its lifetime requirements.
So far, so good, but what is the added value?
The outcomes produced by battery analytics like ACCURE’s, such as state of health predictions, offer additional value beyond simplifying maintenance and helping users improve their operation. The outcomes are a valuable method to address challenges facing the EV industry. The data collected through the EU's Battery Passport initiative can be transformed into actionable intelligence that demonstrably improves the safety, lifetime, and sustainability of batteries while helping to meet the ESG requirements.
Manufacturers and end users will benefit in several ways:
Overall, battery analytics are a win-win for all stakeholders and an important system to achieve the transition to more sustainable mobility, which is a crucial stepping stone to fight climate change.
1 Dana Popp. Batteries: deal on new EU rules for design, production and waste treatment, News European Parliament. Date of last revision: 9 December 2022. Date retrieved: 23 June 2023 [https://www.europarl.europa.eu/news/en/press-room/20221205IPR60614/batteries-deal-on-new-eu-rules-for-design-production-and-waste-treatment]
2 Andrea Casas Ocampo. Battery Passport: The new regulation that determines the future of batteries in Europe, CIC energiGUNE. Date of last revision: 17 January 2023. Date retrieved: 23 June 2023 [https://cicenergigune.com/en/blog/battery-passport-regulation-batteries-europe]
Matthias helps customers gain actionable insights into their battery systems. As Senior Battery Expert and leader of the battery expert team at ACCURE he is responsible for the development of leading-edge battery diagnostics and analytics. As an accomplished systems engineer, Matthias has extensive experience in automotive battery system development. He holds a Master of Science in Electrical Engineering, Information Technology and Technical Computer Science. In his free time, he enjoys sports including soccer, skiing, snowboarding, and jogging.