This article covers:

1. Battery policy in the making
2. Battery lifetime targets are no walk in the park
3. What is the Battery Passport?
4. How will the Battery Passport impact electric vehicles?
5. How battery data can make EV owners’ lives easier
6. Why is determining battery aging and lifespan difficult?
7. Battery analytics addresses challenges faced by the EV industry—and other battery-driven businesses

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As government policies take form, there are uncertainties about how battery lifetime can be monitored, including:

• What will the monitoring schemes look for?
• How should they be implemented?
• How will lifetime benefits be measurable for the safety and sustainability of EV batteries?
• How can lifetimes be prolonged?

So, what exactly is happening on the regulatory side?

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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).

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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?

Could we replace the traditional “Smog check” with a digital solution?

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?

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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 chemical composition of the battery
• The potential impact of the raw materials on the environment
• The amount of CO2 emissions across the entire lifecycle    
• The expected capacity and durability    
• Results from testing key indicators    
• Instructions for safe operation, handling, and storage    
• If and how the battery can be recycled, including safe and environmentally friendly disposal

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

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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:

• The Passport will be mandatory for every battery larger than 2 kilo-watt hours (kWh) starting on the 1st of January 2026.
• Each battery receives a unique ID as part of the Passport together with a set of basic characteristics.
• Throughout the batteries’ lifecycle the Passport will collect more information. Although a detailed list of parameters is not yet defined, it looks like one area of focus will be on collecting information about battery performance and durability.
• The Battery Passport will not only be a digital dataset stored somewhere in the battery system itself (likely in the battery management system). It will also be accessible online under specific regulations.
• The ultimate goal of the Passport is not to collect data but to use the data to make better-informed decisions which will likely influence battery safety, performance, and lifespan of the battery systems.

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?

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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.

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Turning battery data into battery intelligence

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:

1. They can quantify the battery usage patterns. Amongst others, this step tracks the temperatures and states of charge in which the battery is operated.
2. SOH estimations are calculated, tracking how state of health changes over time.

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.