Nothing lasts forever, not even an electric car battery. At some point, it will need to be replaced or refurbished, although if you’ve just bought a new electric car, this isn’t something you need to worry about.
All electric car batteries lose capacity over time. This could be as little as two percent per year, but the rate of decline depends on care and usage of the battery.
Here, we look at some of the considerations.
We’ll start by looking at manufacturer warranties. For example, the battery in a Tesla Model S or Model X is warrantied for eight years or 150,000 miles, whichever comes first. The company guarantees a minimum 70 percent retention of capacity over the warranty period.
You get the same eight-year and 70 percent warranty in the smaller Model 3, but the mileage restriction is 100,000 in the standard range models, or 120,000 miles in the long range and performance variants.
The batteries in the Renault Zoe and Peugeot e-208 are covered for eight years or 100,000 miles. Meanwhile, the warranty in the Nissan Leaf is either five years/60,000 or eight years/100,000 miles, depending on the model.
When estimating battery life, these warranties are a good place to start. If a manufacturer is prepared to warrant a battery for 100,000 miles, that should cover you for around a decade.
How does the battery degrade?
A number of factors determine the rate at which a battery loses its capacity. The simple act of recharging and discharging will eat away at battery life, albeit at a slow and barely noticeable rate.
Some other factors will take larger chunks out of its capacity. These are:
- Use at high temperatures
- Recharging from flat
- Consistent use of rapid charging
- High discharging (fast acceleration)
To preserve the life of your car’s battery, try to keep the charge between 50 percent and 80 percent, using an overnight top-up when possible.
Maintaining battery health
A report published at the end of 2019 using fleet data revealed some interesting data relating to battery health. It can be summarised as follows:
- Most electric car batteries will outlast the life of the vehicle.
- The average decline in energy storage is 2.3 percent a year.
- The biggest losses occur in the first few years, then the rate of decline slows.
- Liquid-cooled batteries perform better. For example, the Tesla Model S (liquid cooling) declines at a rate of 2.3 percent a year. Meanwhile, the Nissan Leaf (air cooling) drops by 4.2 percent a year.
- Higher vehicle use does not equate to higher battery degradation.
- The use of fast chargers speeds up the process of degradation.
In reality, the life of the battery shouldn’t be a major concern unless you’re buying an older electric car. Driven sensibly and charged sympathetically, there’s no reason why the battery pack will see you and the next owner through to a six-figure mileage and beyond.