Battery Health: Passport for the traction battery

The traction battery is the most expensive component in an electric vehicle. Test service specialists are working on a method to assess the battery's residual value in Euros and capacity as a percentage.

Li-ion Battery When selling used battery electric vehicles (BEVs), it is important to know the condition of the traction battery. It is the most expensive component. The vehicle's residual value depends crucially on the range that can still be achieved with the installed battery. However, the actual residual value of the vehicle, including the battery, is still generally an estimate. Vehicle manufacturers do offer a condition assessment via the vehicle's electronics. However, this is not legally binding and is no substitute for a neutral assessment.

That's why our TÜV SÜD experts are working on various battery valuation methods so that in the future they will be able to determine the battery's residual value in euros and its capacity as a percentage or its remaining range in kilometers - independently and with legal certainty. "The vehicle value, including the battery, and the remaining range in kilometers - these are essential details for lease returns just as they are for all used vehicles. If we bring more value certainty to remarketing, we extend the life of BEVs and improve their carbon footprint," explains Pascal Mast, Director New Technologies and Sustainable Services at TÜV SÜD.

This also applies to the use of the battery after the vehicle has been decommissioned and the battery begins its second life as an energy storage device: crash safety, temperature fluctuations, moisture - none of these factors play a role when the battery is used indoors. This means that if an older battery is no longer suitable for use in a car, I can still continue to use it, for example, as a buffer storage unit for the PV system on the roof of the house. Here, too, TÜV SÜD's future battery rating will ensure safety. Long-term goals are a battery passport, which also provides information on the battery's life, and a TÜV SÜD warranty certificate. The battery passport could record safety assessments as part of the general inspection or, for example, the results of damage investigations following accidents.

Already today, every battery with a manufacturer's number has a digital battery passport, a kind of birth certificate. It contains a precise performance description with the date of manufacture and other important data. TÜV SÜD experts are working on turning the birth certificate into a CV. The battery passport could be accessed via a QR code on the battery housing.

In principle, it would also be possible to read data on the battery's condition from the vehicle's battery management system. This raw data could be used to draw conclusions about the condition of the traction battery. As things stand today, however, it is not possible for third parties to simply read out this data via the OBD interface. In the context of the main inspection, this would be the simplest option.

Pascal Mast answers a few questions

Why is TÜV SÜD involved with Battery Health?

P. Mast: When it comes to battery assessment, there are many question marks from the customer's point of view. In particular, the question of the general condition of the traction battery and thus the residual value of the vehicle is at the forefront, but so are safety aspects. At TÜV SÜD, we deal with both aspects.

Who is interested in this?

P. Mast: On the one hand, the condition of the battery is a central question in the used car market; but the question of the condition of the battery is also important when leased vehicles are returned and for mobility providers such as car rental companies: these providers need to know the value of the fleet. This results in important strategic decisions, such as the ideal time to market vehicles as used cars.

Where does the service find application?

P. Mast: In take-back centers, we as TÜV SÜD do the lease take-back and take over the condition inspection of the vehicles. The result is a fair value assessment of the vehicle based on comprehensible criteria, and we have reliable methods for this. However, the battery is still a black box. That's why we want to develop a method for reliably determining the value of the vehicle. The main aim is to determine whether the battery has aged beyond repair.