How batteries age
Calendar ageing, cycle ageing and the mechanisms behind both.
You'll learn
- Explain how batteries age at engineering level
- Read the numbers that define the behaviour
- Apply the idea to a real pack
Overview
Two clocks run at once: one counts time, the other counts energy through the cells. Both consume lithium inventory and raise resistance.
In depth
Degradation simulator
Balance mileage, climate, rapid charging and state of charge habits.
Years of ownership8 yr
Annual mileage15,000 km
Pack capacity75 kWh
Rapid charging share20 %
Average climate20 °C
Time parked above 90% SOC30 %
Estimated SOH
91.4%
Capacity remaining
68.5 kWh
Capacity lost
6.5 kWh
Range lost (at 18 kWh/100 km)
36 km
State of health over time
0 yr8 yr
Stays above the 80% warranty threshold for the whole period modelled.
| Mechanism | Driven by | Effect |
|---|---|---|
| SEI growth | Time, temperature, high SOC | Lithium inventory loss |
| Lithium plating | Cold or fast charging | Sudden capacity loss, safety risk |
| Particle cracking | Deep cycling, high current | Resistance rise |
| Electrolyte decomposition | Heat | Capacity and power loss |
| Current collector corrosion | Over-discharge | Permanent damage |
Key takeaways
Remember this
- Time and throughput both age a pack.
- Heat and high SOC accelerate calendar ageing.
- Cold fast charging risks irreversible plating.
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