The battery is the most crucial and expensive part of an electric vehicle. Generally, electric vehicles are mechanically simpler than their fuel equivalents. This is because there are far fewer parts in an electric vehicle and there is only one gearbox. In total, there are more than a dozen non-existent major parts in the electric car which makes its maintenance less recurrent and less expensive.
This is why most consumers seem to be very concerned about the battery life of an electric car. Replacing the battery in an electric car can indeed cost a fortune. For example, for the Renault Zoé, the price of the battery can cost as high as $8,900.
Yet, even though electric car batteries tend to lose capacity over time, you can be sure that they will never run out of use completely. With that perspective in mind, let’s take a quick look at how an electric battery works, for us to understand its durability.
How Does an Electric Car Battery Work?
The lithium-ion batteries used in electric cars are similar to those used in our phones and laptops, but they are much larger.
These batteries are different from the heavy lead-acid batteries used in conventional cars and have a higher energy density than rechargeable nickel-metal hydride batteries.
Concretely, what does that mean? Lithium-ion batteries do not lose charge capacity when not in use.
The battery capacity of an electric car is expressed in kilowatt-hours (kWh). More is better here. Choosing an electric vehicle with a higher battery capacity is a bit like buying a car with a larger gas tank. You will be able to travel more kilometers before having to refuel.
Note: The management system of an electric car prevents the battery from being charged to 100% or from being discharged to 100% to preserve its efficiency and prolong its life.
Although an electric vehicle battery tends to degrade slightly with each charge and discharge cycle, it is an extremely slow process. For example, the battery of a Tesla Model S would only lose about 5% of its initial capacity during the first 50,000 kilometers, and this rate will be lower after this cap.
The Battery Life
Regular discharge and recharging are what generates wear and tear in electric batteries over time. Car manufacturers generally advertise an average lifespan of 1,250 charge cycles (from 0 to 100% therefore, and not each time you plug in the vehicle), for typical everyday use.
This would correspond to a minimum of 8 to 10 years depending on the motors and batteries, and the battery would only provide 70 to 80% of its capabilities beyond this (at a rate of approximately 2.3% of capacity lost per year).
To illustrate this, assuming that your car is equipped with a 50-kWh battery and that you drive 20,000 km per year (or 55 km per day) and at a rate of consumption of 20 kWh / 100 km, this amounts to a range theoretical 250 km per cycle. This corresponds to approximately 80 complete charge cycles per year.
Taking into account that it is better to keep the charge between 30 and 70% to preserve the battery, rather than dropping to 0% and doing full cycles each time, we can assume that this equates to between 100 and 110 cycles per year. If we rely on the 1,250 cycles denoted by the manufacturer, this equates to a lifespan of almost 11 years!
Reassuring, isn’t it? Add to this the fact that the maintenance of an electric car mainly consists of checking the health of the battery, and the lifespan will be nothing more than an old worry.
What factors affect battery life?
- The climate: Temperature has a strong influence on a lithium-ion battery, but it is important to distinguish between long-term battery wear (its lifespan) and short-term battery performance. Heat can have a long-term negative effect on battery life, although it does not affect battery performance. Conversely, extreme cold can have an impact on the short-term performance of electric car batteries. But it will have absolutely no impact on the durability of the battery.
- Extended parking: Prolonged parking of the electric car, when the temperature is high and/or when the battery is full, can also hurt the durability.
- The charging frequency: the battery degrades when it heats up too often, which is the case with frequent recharging on the most powerful, ultra-fast charging stations.
The Bottom Line
Electric vehicle batteries undergo cycles of ‘discharge’ that occur when driving and ‘charge’ when the car is plugged in. Repeated charging and discharge, over time, affect the amount of charge the battery can hold. This decreases the range and time needed between each journey to charge.
Most EV battery manufacturers have a five to an eight-year warranty on their battery. However, the current developments and predictions are pushing these limits, and indications are electric car batteries will last from 10 – 20 years before they need to be replaced.