Electric car battery: service life, warranty, repair

The battery is the most important and expensive component of an electric car. That's why buyers want to know: How long does the battery last? What guarantees does the manufacturer give? Can batteries be repaired? ADAC guide with lots of tips and information.

• Batteries usually have a long service life

• Guarantee promises are getting better and better

• Summary table with all manufacturer's warranties

• Battery Testing and Certificate

Manufacturers of electric cars make very generous promises about the service life of the traction batteries. Nevertheless, prospective buyers worry about whether they will be left alone by the manufacturer if the battery loses capacity over the years of use and the range of the car is reduced. Is there any repair under the manufacturer's warranty? Or does the buyer have to bear the full costs?

A long service life is realistic

Trust in the expensive batteries and the reliability of the manufacturer's promises is necessary for the acceptance of electric cars. This is because customers know from electronic devices such as cell phones or laptops that batteries lose power over time and intensity of use (degradation) and that they have to be replaced.

The good news is that unlike the lithium-ion batteries installed there, electric cars have intelligent battery management. This measures the temperature and voltages of each individual cell in the battery. This ensures that they do not overheat or become too cold and thus lose performance. The aim is always to protect the cell chemistry as much as possible.

The systems seem to be proving themselves well: The ADAC has tested in several long-term tests of the first electric cars on the market that an acceptable battery life can actually be achieved (the links can be found under this article). Take the BMW i3, built in 2014, for example: After five years and 100,000 kilometers, the energy capacity of the battery was still 86 percent. The ADAC engineers cautiously assume that the decrease in capacity to 70 percent would only have taken place after about 200,000 kilometers. That would be extrapolated after 10 years.

As a result of the further development to this day, the manufacturers – with a few exceptions – have agreed on a battery warranty of eight years and 160,000 kilometres. Lexus is already giving the new UX300e 10 years and 1 million kilometers – a figure that sets new standards.

Usually, the warranty is vehicle-related, but some manufacturers require the remaining warranty claims to be assigned to the used car buyer. The ADAC sample purchase contract therefore also includes the assignment of the warranty. If the vehicle is purchased from a car dealer, it is also advisable to clarify the remaining warranty claims and assign them in writing.

Manufacturer's warranties for the batteries

In contrast to the legally enshrined liability for material defects for the first two years, the warranty is a contractual agreement between the manufacturer and the buyer. But can you also rely on the manufacturer's warranty promises? Are there pitfalls in the small print?

Important: The manufacturers only ever give a guarantee for a minimum proportion of usable battery capacity within a certain service life. This minimum limit is set by manufacturers for almost all electric models at 70 percent after eight years of operation or 160,000 kilometers. If, for example, a battery no longer reaches this 70 percent capacity after six years of operation after a full charge, a warranty claim can be claimed. If the warranty claim is accepted by the manufacturer, he replaces individual battery modules or replaces the entire battery at his expense. In the chapter below, you will learn how battery modules can be repaired.

Rules of use must be observed

What most car owners are less aware of is that they should know and observe the user rules defined in the user manual and warranty conditions of their electric car. Otherwise, there is a risk of losing possible claims. The requirements and rules essentially include that the electric car must be serviced in good time according to the manufacturer's instructions.

In addition, there are additional reasons for exclusion with regard to warranty service:For example, improper work or improper repair or retrofitting of the car. This also includes towbars, provided that no towing capacity is entered in the registration certificate ex works.

Advice from the manufacturer to charge the battery as rarely as possible with a high charging power or not to always fully charge the battery is more likely to be understood as a recommendation for a longer battery life. According to the manufacturers, if these recommendations are not observed, this does not automatically lead to the exclusion of the warranty.

Deep discharge can jeopardize warranty

More problematic is the deep discharge of the battery due to longer service life, even if the manufacturers do not handle this issue uniformly, as the ADAC manufacturer survey showed. For some manufacturers such as Nissan and BMW, deep discharge is a clear reason for excluding the warranty. Other manufacturers look at these situations on a case-by-case basis, and still other manufacturers – above all the VW Group – say that deep discharge in their vehicles is out of the question by design.

In normal everyday life, deep discharge is unlikely to play a role. However, this can be quite relevant if you are on holiday for several weeks or if an e-vehicle is at the used car dealer for a long time. Used car buyers should therefore ask how long the vehicle has been parked and have the seller contractually assure them that the vehicle was not deeply discharged and was recharged regularly.

Software updates are usually mandatory

There could also be problems if a software update (SW) from the manufacturer has been missed. If a software update is declared as a result of a recall or as a service measure, it is to be regarded as mandatory. Failure to perform may have a negative impact on a subsequent warranty claim. At Tesla, performing any SW updates is a prerequisite for granting warranty claims. And Škoda also inevitably carries out SW updates as part of maintenance.

Clearly verifiable: Improper handling

But how does the manufacturer know about improper treatment, if any? Can he prove that in case of doubt? The answer is clear: manufacturers know very well about the history of the battery. Critical conditions of the electric car battery are stored together with environmental data in the battery management system or transmitted directly online to the manufacturer.

Guarantees remain legally unclear

Even if the manufacturer's warranty promises sound generous, from a legal point of view, it unfortunately remains unclear to what extent the information in the operating instructions is to be understood merely as recommendations or as warranty-relevant regulations. That's why buyers should be careful and stick to the user rules. Otherwise, in case of doubt, they could be dependent on the goodwill of the manufacturer or even come away empty-handed.

Battery certificates – the ADAC helps

The traction battery is the most expensive component in an electric car and, due to its principle, wears out over time and use. The more charging cycles, the more aging occurs. It is therefore important for the owner, even in the event of an intended sale, to know the state of health of the battery ("State of health" = SOH) as precisely as possible and to be able to prove it objectively. During regular maintenance and checks in the manufacturer's workshop, the traction batteries are checked for their condition. It is therefore advisable to have the test report of the battery handed over to you by the workshop. So far, however, the workshops have not wanted to do that. And if they do, they may charge a hefty fee for it.

In the meantime, the ADAC, in cooperation with its partner Aviloo, offers a manufacturer-independent and neutral battery check for pure electric vehicles, but also for plug-in hybrids. You can find out how to get the certificate and what it costs here.

What manufacturers should do:

• Regularly inform the customer about the state of health of the battery's SOH (State of Health) – ideally directly in the vehicle or at least during maintenance in the manufacturer's workshop. This gives the customer information about the current condition of the battery and also proof when the vehicle is resold.

• Provide transparent information in the purchase documents about the usable capacity in new condition.

• Clearly point out warranty-relevant information in the operating instructions.

• Make more precise capacity differentiations for age and mileage (e.g. 90 percent are guaranteed for 2 years/40,000 kilometers, xx percent for 4 years/80,000 kilometers).

• For warranty repairs, depending on age and mileage, specify the minimum percentage of capacity to which the battery will be restored.

What electric car buyers can do:

• Read information on warranty conditions carefully.

• Have the usable battery capacity certified when new.

• Follow the operating instructions for longer battery life.

• Observe instructions for longer idle times (recharging and risk of deep discharge).

• Strictly adhere to all maintenance intervals.

• Assert warranty claims immediately.

• For the examination of a warranty case, clarify the costs in advance.

• Be sure to have software updates carried out in the event of recalls or service campaigns.

• When buying a used car, observe the warranty conditions at the time of purchase.

Replacement of individual battery modules

All manufacturers who bring battery-electric cars to market must build up capacities for battery repairs and train workshop staff in the use of high-voltage technology. The topic was in its infancy for a long time, and the workshops were often completely overwhelmed. However, with increasing age and the increasing number of electric vehicles, manufacturers are now preparing for the tasks of the future.

Take Opel, for example: The Rüsselsheim-based company has set up a "Battery Refurbishment Center" at its headquarters. Here, specially trained technicians take care of those cases where the dealers cannot help. In 2020, there were around a hundred defects in the e-car fleet, in which, for example, a control unit no longer worked properly or a battery cell had said goodbye. In such a case, the company says, the entire battery pack is sent to the repair center in Rüsselsheim. The customer receives a replacement battery from the warehouse, and the repaired battery is returned to the warehouse.

At least that's how the processing works within the framework of the manufacturer's warranty at Opel. However, for repairs outside the warranty period, this exchange procedure appears to be time-consuming, and workshops should also be able to successively carry out battery repairs on site.

Because in principle, a complete replacement of the battery is not mandatory and even rarely necessary. Batteries can also be restored to a condition suitable for everyday use by replacing individual modules. This is particularly important for customers whose electric cars have already exceeded the warranty period on the battery.

Volkswagen has given the ADAC an insight into how a battery repair works in detail. "In principle, all our workshops can carry out repairs on electric vehicles," explains Linus Hentrich, Technical Qualification Specialist. However, if a dealer needs to carry out repair work inside the battery, the vehicle is handed over to the high-voltage expert at one of Volkswagen's approximately 450 repair centres.

The high-voltage expert begins the procedure with a comprehensive diagnosis, in which the existing data is read out and measurements are carried out. Then, if necessary, the battery pack is removed from the car and the well-screwed and carefully sealed battery housing is carefully opened. Before work can be carried out on the modules, the circuit within the connected battery modules must be interrupted and the capacitor must be energy-free. Only then can you start to take out a single module.

In the ID.4, the largest battery consists of twelve modules, the small one of nine. Each battery module in turn consists of several units, the cells. Individual cells are not repaired, but an entire module is always replaced that is faulty or if the energy capacity is severely limited.

Important: The new module must be adapted to the voltage level of the other modules in the overall package. This means that the possible voltage level is specifically set in the replacement module – before it is installed. The voltage is equalized by means of an electronic device, the so-called module balancer. This device is only available at repair centers that are professionally trained and can handle it.

Repairing a module is of course much cheaper than replacing the battery completely. A module repair takes about one day, including the removal and installation of the entire battery housing and tests. A module repair is therefore roughly comparable to a repair of engine damage in terms of effort and cost.

Unfortunately, manufacturers still find it difficult to provide information about specific prices for a battery repair after the warranty has expired, even if they should be able to estimate the material and time required very well. It is to be hoped that manufacturers would address customer concerns with transparent information on repair costs.