For a long time, skepticism towards electric cars was also due to the potentially short lifespan of the battery. However, this is now considered to be a particularly reliable component.
For a long time, the engine was the most expensive component in the automotive world. With good care, 200,000 to 300,000 kilometers was considered the limit of durability. Its expected or assumed reliability was a particularly important purchase criterion for car customers. In the case of electric cars, however, the battery is the largest cost item. Its condition is crucial for the lifespan of the car. If the traction battery is defective, this can lead to total loss.
Unfortunately, sudden battery death is not a myth spread by petrolheads, but a bitter reality for some e-drivers. However, the durability of batteries is now easier to calculate and the expected lifespan is even extraordinarily long. In many cases, it may even extend far beyond the lifespan of the vehicle. This is due, among other things, to ever-improving software and cell chemistry. Regardless of the state of the art, however, the user and the usage profile will continue to have a major influence on the condition and lifespan of the battery.
Indicators: high mileage and long warranty
There are certainly several signs that batteries are no longer capricious and error-prone components. One indicator is the high mileage of some used electric cars. Of the approximately 75,000 electric vehicles currently advertised on the used car platform mobile.de, 450 have a mileage of 150,000 kilometers. Around 150 have more than 200,000 kilometers on the clock. Some, and these are exclusively Teslas, have even exceeded 300,000 kilometers. So high mileage and electric drive are not mutually exclusive.
Another indicator of the reliability of the batteries is the increasingly generous guarantees offered by car manufacturers. When the first electric cars came onto the market in large series, the fear of a battery fiasco was often countered with rental models. In these models, only the car is purchased, but not the battery, which is rented for a monthly fee. If the battery degrades significantly or fails completely, the manufacturer and not the car owner bears the financial risk.
However, generous guarantees are now being offered specifically for batteries. Manufacturers' and insurance companies' confidence in their reliability has increased significantly with increasing practical experience, and with it the scope of the guarantees. Today, 8 years or 160,000 kilometers is the norm, especially for the battery. In individual cases, 10 years or up to 250,000 kilometers are also granted. Lexus offers a guarantee extension of 10 years or one million kilometers for the UX 300e. From a customer's perspective, these are strong statements.
Battery may also be excluded from the warranty
But this is not always a safe option. If the battery is exposed to excessive stress factors, the warranty may be voided. Deep discharge, failure to service or charging behavior that places too much strain on the battery could give the manufacturer the appropriate arguments to refuse to provide the customer with warranty service. If you want to be on the safe side, you should pay attention to the exact conditions and usage recommendations that the manufacturer associates with the warranty.
The warranty does not only apply when a battery fails completely, but when the charging capacity falls below a certain level. Information about this is provided by the SoH value (State of Health), which indicates in percent how much of the original capacity is still available. If the capacity falls below around 80 percent of the original storage capacity within the warranty period – in some cases the warranty limit is 70 percent – the warranty applies. If it is only 79 percent, the battery is not defective, but the range has been significantly reduced. In cars with a long range, this does not rule out everyday use. In city cars with small batteries, however, the loss can lead to an annoying restriction of the range.
Influence on State of Health
Several factors influence the state of health. One of them is time, as a battery ages because the anode and cathode are exposed to chemical decomposition processes. In addition to this chronological aging, the number of charging cycles is probably the most important aging factor. With each charge, part of the capacity is lost.
With lithium-ion batteries, it is assumed that the capacity only falls below 80 percent after more than 1,000 complete charging cycles. This figure alone is impressive, because given that the average range of electric cars in 2023 is around 400 kilometers, roughly speaking and without taking dynamic degradation into account, mileages of 400,000 kilometers would be possible.
However, this is a theoretical value, as the degradation of a battery is influenced by other factors that depend on individual user behavior. If you drive quickly, the battery will be subjected to greater thermal stress when the power is reduced. Extreme outside temperatures can also damage the battery cells. If you park your electric car in a garage with even air conditioning and not in the blazing sun or outside on frosty days, you will slow down the downward trend of the degradation curve.
Charging behavior has a big influence
Charging behavior also has a strong influence. If charging is done primarily at fast charging stations, the degradation curve will move downwards much more quickly over time, as fast charging also means thermal stress for the power storage unit. Slow and therefore gentle charging overnight at the home wall box, i.e. gentle AC charging, causes the battery to age more slowly, as laboratory tests at cell level and real examples from e-car users show. But that does not mean that the fast charging station is taboo. Occasional visits will have only a minor impact on the long-term SoH development over the entire aging process of the battery.
The state of charge (SoC) also has a significant influence. Frequent discharging of the battery and thus a frequent SoC close to 0 percent and subsequent full charging (SoC 100%) causes the battery to age more quickly. If extreme charging states are avoided, degradation slows down. If charging is mainly done in partial cycles in the SoC range between 60 and 80 percent, experts expect a three to five times longer service life. It is more practical to keep the charge state between 20 and 80 percent.
Bandwidth in service life
The scientist and YouTuber Andreas Schmitz, known as the “battery doctor”, gave two extremes of battery aging as examples in a recent video on the lifespan of electric car batteries. A Tesla Model 3, which was used as a taxi in Norway, reached the critical SoH value of 80 percent after an estimated 110,000 kilometers due to a fast charging rate of 93 percent. Hansjörg-Eberhard Freiherr von Gemmingen-Hornberg, on the other hand, has already covered more than two million kilometers with a Tesla Model S P90 and, although several batteries have worn out in the process, they have lasted an average of almost 500,000 kilometers.
These examples show a range in the service life. But Andreas Schmitz wanted to know how many kilometers can be expected on average until the SoH value of 80 percent. To do this, he collected data from surveys in his community and from forums in order to generate calculation models for wear. The statement, smoothed out by any inaccuracies: 250,000 to 300,000 kilometers should definitely be possible with normal use. As of today. Other cell chemistries such as nickel-manganese-cobalt (NMC), sodium ions (Na ions) and above all lithium iron phosphate (LFP) are considered to be particularly cycle-resistant and should therefore enable significantly longer ranges in the future than the lithium-ion batteries that have been common up to now. The Chinese company Svolt promises a service life of more than 2,500 charging cycles and over a million kilometers for its short blade battery (LFP), which will be available from the end of 2024.
Battery-saving use
Those who use their electric car in the most battery-friendly way possible not only benefit from a longer range, but also potentially from a higher resale value. Interest in battery certificates that provide information about the SoH is likely to increase significantly in the used car trade. With a high SoH value, sellers are in a good negotiating position, which of course enables them to charge higher prices. If the used car market for electric cars becomes more economically relevant, counterfeiting battery certificates could one day become an attractive business model.
This also applies to retrofitting batteries. A car battery that is already very worn out does not have to mean the end of the electric car. There are now a number of providers of retrofit solutions that equip older electric vehicles with new batteries. Mandrill Automotive from Göppingen, for example, offers this for the electric pioneer BMW i3. A new power storage unit in the long-range 120 Ah format costs around 13,600 euros and offers significantly more capacity than the 60 or 94 Ah versions originally installed by BMW. In a report in “Auto Motor & Sport”, Mandrill announced a new battery format with different cells and different cell chemistry with 147 Ah, which could increase the range of the i3 to 400 kilometers. The battery tuning for the i3 that is already available is even provided with a 10-year guarantee.
In practice, the lifespan of the batteries will be significantly longer anyway. This is because decommissioned traction batteries do not end up in the scrap yard straight away, but are given a second use as stationary storage, for example for solar power. This second life can last another ten years.
