Are fears around EV battery decline grounded in reality?

The new EV market is firmly on the up. In Europe, pure electric cars accounted for 21% of the market in August, while pure electric car sales also surpassed diesel vehicles for the first time in June, according to The European Automobile Manufacturers’ Association (ACEA). All indicators reflect the growing prominence of EV and yet, important question marks remain when it comes to the used market.

To many, a used electric vehicle represents a potentially risky investment, with no guarantee of performance outside of the warranty period. EV batteries account for a significant portion of the overall vehicle value and are prohibitively expensive to replace in the event of a battery failure. This fear undermines confidence in used vehicles but are such concerns legitimate? Or do they speak to a general lack of understanding around EV battery health, and the measures that can be taken to restore optimal battery health and range?

Comparing EV batteries with cell phone batteries

One of the primary misconceptions around electric vehicle batteries is that they would not fail due to a lack of moving parts. Experience has revealed this view to be inaccurate, due largely to the rising demands placed on EV batteries.

To put this in context, we can look at the decline that occurs within cellular phone batteries, which bear many similarities to those based on lithium-ion chemistry that are used in EV batteries. After 18-24 months, charging capacity is invariably lower than the original level. As the number of charge cycles rises, the bonding and debonding of the chemistry will not work in the same way, which diminishes the ability to re-charge. The rate of decline is typically determined by how often we are charging and discharging batteries which, in the case of cell phone batteries, is rarely more than once or twice a day. If the number of charge cycles remains low i.e., the battery is not charged and re-charged on a regular basis, then the battery is far less likely to fall below the required performance level.

The demands placed on lithium-ion batteries in EVs are significantly higher, and if we consider that a Tesla battery contains, in essence, 7,000 battery cells, we can see how the statistical probability of one of the batteries aging at a faster rate, increases. A single faulty cell can compromise the performance of the entire pack.

The changing role of EVs brings heightened expectations

Some of the earliest EVs to reach the market offered power densities of 24 kWh, which is significantly lower than current standards. Such vehicles were typically bought as a second car, often for families, and used for relatively short distances and without the need for fast charging.

Subsequent improvements in performance, with power densities in excess of 60 kWh, and the availability of fast charging, means that electric cars are now being used as a primary mode of transport. As EVs have gone mainstream, they are now exposed to a much higher set of demands.

Higher power density requirements carry additional complexity in terms of battery designs. Excess heat generation needs to be managed with the integration of cooling systems and is yet another hurdle for manufacturers to overcome. While EVs remain reliable, the fact that technical boundaries are continually being pushed to the limits increases the scope for faults. As battery designs become increasingly diverse on both a chemistry and design level, this also presents new challenges.

Battery faults – temporary setback or permanent problem?

Because of the misguided view that EV batteries would not fail, previously some manufacturers did not design batteries for repairability and instead pursued a strategy of simply replacing failed batteries. Given the significant financial and environmental costs of this approach, the need for a robust repair and servicing process to account for the potential for faults became apparent.

A single underperforming cell undermines the performance of the battery as a whole, given that the battery pack will only perform to the level of its worst performing cell. In recent years, this accelerated drop in performance would have rendered the battery pack inoperable far in advance of its potential lifespan. In this scenario, battery packs would have been sent for premature incineration, ignoring the fact that a large portion of the cells and components were still suitable for use, as well as the heavy environmental cost of the recycling process.

Our advancements in EV battery testing through our REVIVE™ offer now make it possible to pinpoint underperforming or faulty cells on an individual level. This capability means that we can address the root causes of decline, both reactively, and proactively, since our pioneering use of digital twins also allows us to spot cells that are at risk of underperforming. Armed with these insights, corrective action can be taken before we see an adverse impact on performance.

The big picture for EV battery health

When we can accurately diagnose underperforming cells, we can replace them with existing cells to restore optimal performance. In practice, this allows us to reverse the effects of cyclical ageing, which yields drastically better battery range and ensures maximum battery longevity.

All of this is contingent on having a controlled and repeatable process for replacing modules or cells, as it enables fault-free repairs to be carried out both safely and at scale. To put this into perspective, Autocraft EV Solutions has already carried out thousands of EV battery repairs with zero repeat failures attributable to faults within the repair process – anything less than this cannot be accepted.

As the number of EVs continues to rapidly increase, it is only a matter of time before the aftermarket will need to be able to provide this kind of service. The future success of EV will depend on battery reliability, and we already have a proven method for optimising battery health and longevity, working with manufacturers to insulate them from warranty costs and reputational risk.

Our use of existing modules allows us to deliver on performance requirements with a drastically reduced environmental footprint, helping to fully unlock the ecological benefits of electric vehicles and strengthen their appeal as an alternative to other carbon-emitting forms of transport.