How does a battery age?
Back home. The car is four years old and has driven 61,000 km. In the app, battery health shows 94%.
When new, the battery held 70 kWh. Today it holds about 66.
The questionWhat does 94% mean, and how will that number develop?
Guess firstHow much capacity do electric car batteries lose per year on average, according to telematics data from more than 22,700 vehicles?RevealHide
About 2.3% per year on average, up to 3.0% for cars that fast-charge above 100 kW often, around 1.5% for cars that mostly charge with AC.
State of health
compares what the battery holds today with what it held when new. At 94%, the 70 kWh battery holds about 66 kWh. The range falls in proportion; the car drives as before.
Lines: average annual loss in telematics data from over 22,700 vehicles of 21 models, by charging behaviour. Shown as straight lines; real batteries often lose a little more in the first months. Dotted steps: the Euro 7 minimum for new cars, 80% up to 5 years or 100,000 km, 72% up to 8 years or 160,000 km, whichever comes first.
Two kinds of ageing
- Calendar ageing happens with time, faster when the battery stands hot or full for long periods. Cars in hot climates lost about 0.4 percentage points more per year in the same study.
- Cycle ageing comes from use: energy in and out, and above all high power. Frequent DC charging above 100 kW raised the loss to up to 3.0% a year, against about 1.5% for mostly AC charging.
The limits both: it keeps a reserve at the top and bottom of the battery and controls temperature and power.
What EU law sets
Euro 7 sets a minimum durability for the batteries of electric and cars: 80% of the certified energy up to 5 years or 100,000 km, and 72% up to 8 years or 160,000 km. It applies to new car types from 29 November 2026 and to all new cars from 29 November 2027.
Check your understanding
3 questions. Answer all of them to complete this stop. Each answer explains itself.
What does a state of health of 94% mean?
State of charge says how full the battery is now. State of health says how much it can hold compared with when new.
Which charging behaviour went with the fastest ageing in the telematics study?
Frequent high-power charging went with up to 3.0% loss a year, mostly AC charging with about 1.5%.
What does Euro 7 require for the batteries of new electric cars?
The minimum performance requirements apply to new types from 29 November 2026 and to all new cars from 29 November 2027.
- BMS Battery management system: the car's electronics that decide how much power the battery accepts at each moment. EV charging fundamentals, stop 04 Glossary
- Plug-in hybrid A hybrid with a socket and a larger battery, so everyday distances can run on grid electricity and longer trips on fuel. Stop 01 Glossary
- State of health How much energy the battery can hold today compared with when it was new, in percent. Glossary
- Geotab: Updated analysis finds average battery degradation of 2.3% per year, with charging behaviour emerging as a key driver, 13 January 2026. https://www.geotab.com/uk/press-release/ev-battery-health-degradation-fast-charging-study/. Checked 09 Oct 2026.
- EUR-Lex: Regulation (EU) 2024/1257 (Euro 7), Article 20 and Annex II: minimum performance requirements for battery durability. https://eur-lex.europa.eu/eli/reg/2024/1257/oj. Checked 09 Oct 2026. © European Union, reused under Commission Decision 2011/833/EU.
- Geotab: Updated analysis finds average battery degradation of 2.3% per year, with charging behaviour emerging as a key driver, 13 January 2026. https://www.geotab.com/uk/press-release/ev-battery-health-degradation-fast-charging-study/. Checked 09 Oct 2026.
- Geotab: Updated analysis finds average battery degradation of 2.3% per year, with charging behaviour emerging as a key driver, 13 January 2026. https://www.geotab.com/uk/press-release/ev-battery-health-degradation-fast-charging-study/. Checked 09 Oct 2026.
- EUR-Lex: Regulation (EU) 2024/1257 (Euro 7), Article 20 and Annex II: minimum performance requirements for battery durability. https://eur-lex.europa.eu/eli/reg/2024/1257/oj. Checked 09 Oct 2026. © European Union, reused under Commission Decision 2011/833/EU.