EV Battery Health Calculator
Estimate your EV battery's current capacity and how it will degrade over time — based on your driving habits, climate, and charging behaviour.
How EV batteries degrade — and how to slow it down
All lithium-ion batteries degrade over time. The question isn't if your EV battery will lose capacity — it's how much, and how fast. The good news: modern EV batteries degrade much more slowly than early smartphones, and real-world data from large fleets suggests degradation is manageable over a typical ownership period.
Studies from Tesla, Nissan, and large fleet operators (plus academic research) show a consistent degradation curve: rapid initial loss of 2–5% in the first year, then a slower decline of 1–2.5% per year thereafter. The Tesla Model 3 fleet data from Teslamotorsclub shows an average loss of around 10% capacity after 100,000 km.
- Heat is the enemy: High temperatures accelerate electrolyte degradation. Parking in the sun in Darwin will degrade your battery faster than parking in a cool Melbourne garage. This is why Teslas in hot US states (Arizona, Florida) show higher-than-average degradation in fleet data.
- Fast charging: DC fast charging pushes large amounts of current through the battery quickly, generating heat. Occasional fast charging is fine — it's what the car is designed for. Daily fast charging, especially to 100%, accelerates wear noticeably over years.
- The 20–80% rule: Most EV manufacturers recommend keeping daily charge between 20% and 80%. This avoids the electrochemical stress that occurs at both extremes of charge state. Many EVs let you set a charge limit — use it.
- Australian warranty: Most EVs sold in Australia carry an 8-year / 160,000 km battery warranty (whichever comes first), with a capacity threshold — typically 70%. Tesla warrants 70% retention; Hyundai, Kia, and BYD offer similar coverage.
- Battery chemistry matters: Newer LFP (lithium iron phosphate) batteries, used in base-model Teslas, BYD vehicles, and others, degrade more slowly and can actually be safely charged to 100% daily. NMC (nickel manganese cobalt) chemistry, used in most other EVs, benefits more from the 20–80% rule.