If you are thinking about buying a used electric car, there are some important factors to consider:
How much will the electric car cost?
What is its range?
How long will the battery last?
From a lifecycle perspective, battery performance and health are really the most important things to consider. Since the battery is the most expensive component in an electric vehicle, not only does the condition of the battery affect the residual value of the vehicle (helps answer the cost question), but it also has a direct impact on the electric vehicle’s range.
How long will an electric car’s battery last?
It’s difficult to get a straightforward answer to the question of battery life. Instead, you can find statements from electric car manufacturers that the batteries are covered under warranty if something goes wrong. Generally, the warranty is 8 years/160,000 km, but that depends on the manufacturer and country.
What’s encouraging is that the cost of batteries is dropping significantly each year.
The automaker’s battery warranty should inspire some confidence. However, it’s interesting to know how quickly your battery degrades over time and how to minimize that loss?
What is electric vehicle battery degradation?
Battery degradation is a natural process that continually reduces the amount of energy a battery can store, or the amount of power it can deliver.
The state of health or degree of performance of the battery is determined by the State Of Health (SOH) parameter. The SOH is usually 100% for a new battery and gradually decreases over time, depending on operating conditions. The SOH is a measure of how much energy a battery can deliver (kW⋅h).
Keep in mind that this is not the same as a vehicle’s range (the distance the vehicle can travel those kilowatt-hours). The range of an electric vehicle depends on a number of factors, including charge level, topography, temperature, driving habits, and passenger or freight loads.
The main factors affecting the health of a lithium-ion battery pack are:
Time.
High operating temperatures.
Use at low charge levels (completely discharging the battery).
High electric charging current.
Usage (energy cycles).
While there have been many studies on battery condition, very little data has been obtained on the actual performance of electric vehicles over time, let alone comparisons between different makes and models to date.
Geotab analyzed the condition of 6,300 batteries from fleet and consumer electric vehicles. Based on the processed telematics data, the company gained insight into how real-world conditions affect the performance of electric vehicle batteries, providing aggregated average degradation data for 21 different electric vehicle models, including different model years.
The company even developed a tool to compare average battery degradation over time for different vehicle makes and models. Degradation is based on observational data, so newer electric cars will have shorter lines of degradation rates.
Geotab cautions that these graphs can give an indication of average battery degradation over time, but should not be interpreted as an accurate prediction for a specific vehicle. Also, if your model of electric vehicle is missing from the tool, it means the company received little data on it and excluded it from the tool.