EV battery degradation is the question used EV buyers ask us more than any other, and it’s also the most over-worried. The short version: most EV batteries are ageing better than the early predictions said they would, but the variance between cars is wide enough that you should absolutely check the specific car you’re buying. Here’s what’s really happening, without the FUD or the cult.
What degradation actually is
An EV battery loses capacity over time. The same pack that delivered 60kWh new might only deliver 54kWh after seven years. That’s a 10% loss, which takes real-world range from 400km down to 360km. Degradation comes from two mechanisms:
- Calendar ageing: the battery degrades just by sitting there, even if you never drive it. Heat speeds this up a lot.
- Cycle ageing: every full charge and discharge wears the cells a little. Modern batteries are good for 1,500 to 3,000 full cycles before the loss gets serious, which works out to hundreds of thousands of kilometres.
The implication: kilometres alone are a poor predictor of battery health. A 5-year-old car with 30,000 km in a hot Brisbane garage may be in worse shape than one with 80,000 km in temperate Melbourne.
The real-world numbers
The largest studies of EV fleet data tell a consistent story:
- Geotab tracked over 6,000 fleet EVs and found average degradation of 1.8% per year, so a typical 8-year-old EV averages 86% SOH.
- Recurrent’s analysis of 20,000+ used EVs shows much the same: most batteries retain 80%+ capacity at 8 years, and the curve flattens over time rather than getting steeper.
- Tesla’s own fleet data, published in their 2024 impact report, shows Model 3/Y batteries retaining around 85% capacity after 200,000 miles (320,000 km).
That’s the average. The variance matters more.
What makes one car degrade faster than another
Heat exposure (the biggest factor)
Heat is the enemy. A car parked outdoors all summer in Perth, Brisbane, or Darwin will degrade meaningfully faster than the same car garaged in Hobart or Melbourne. The early Nissan Leafs are the cautionary tale here: air-cooled packs in hot climates lost 20%+ capacity in 5 years. Modern EVs all use liquid cooling, which cuts the effect right down, but it’s still real.
Charging behaviour
Three habits accelerate degradation:
- Sitting at 100% charge: only charge to 100% when you’re about to drive. Daily charging to 80 to 90% (the manufacturer-recommended setting on most EVs) is much gentler.
- Sitting near 0%: letting the battery sit at very low charge for days or weeks is harmful. Park around 30 to 60% if leaving the car idle.
- Constant DC fast charging: moderate DC use is fine. Daily 150kW+ charging on an NCM pack accelerates wear. LFP packs (Atto 3, MG4, post-2021 Tesla RWD) are largely immune.
Ex-fleet and ex-rideshare cars often have unusual charging histories, so ask about them. See our guide to checking used EV battery health for how to verify.
Battery chemistry
The chemistry matters more than the brand:
- LFP (lithium iron phosphate): ages slowest, tolerates 100% daily charging, less affected by heat. Used in BYD Blade packs, post-2021 Tesla Standard Range, MG4 Standard Range.
- NCM/NMC (nickel-cobalt-manganese): higher energy density (longer range) but ages faster. Used in most “long range” packs: Tesla Long Range, Hyundai/Kia E-GMP, Polestar 2, BYD Seal.
- NCA (nickel-cobalt-aluminium): highest density, earliest Tesla packs (Model S, original Model 3). Ageing is comparable to NCM with good cooling.
None of these is “bad”, but if maximum longevity is the priority, LFP is the safer bet.
What degradation looks like over a car’s life
The degradation curve is non-linear. The first 1 to 2% drops in the first year (the “early loss”), then it settles to around 1% per year for the next 5 to 7 years, and it may steepen slightly after that. Roughly:
- Year 1: drops to ~98%
- Year 3: ~94%
- Year 5: ~91%
- Year 8: ~85%
- Year 12: ~78%
Manufacturer warranties typically guarantee 70% capacity at 8 years. Most cars will exceed that comfortably.
What 90% SOH feels like behind the wheel
If a car had 400km WLTP range new, at 90% SOH it has roughly 360km. In real-world terms (allowing for the typical 5 to 23% real-world reduction the AAA measured in Australian conditions), that’s around 290 to 330km practical range. For most Australians driving 50km a day, that’s still 5 to 6 days of commuting between charges. Degradation only really bites on long road trips, and even then it shifts your charging stops by 30 to 50km, not by hours.
The cars where degradation really hurts are ones that started with marginal range. A 200km Leaf at 80% SOH is genuinely limited. A 500km Model 3 Long Range at 80% SOH is still a 400km road tripper.
How to interpret a battery health certificate
If you’ve followed our battery health check guide, you’ll have an SOH percentage. Here’s how to read it:
- ≥95% on a 1 to 3 year old car: excellent, no concerns
- 90 to 95% on a 3 to 5 year old car: entirely normal
- 85 to 90% on a 5 to 7 year old car: normal, factor in mild range reduction
- 80 to 85% at any age: noticeable range loss; discount the price by 5 to 10%
- Below 80%: significant. Discount heavily or walk away unless the price reflects it
- Below 70% within warranty period: manufacturer should replace under warranty
Check the car, not the average
Modern EV batteries are ageing much better than early sceptics predicted. The average car is fine. But the variance is wide enough that buying on averages is risky: you need to check the specific car you’re considering. Spend $200 on a battery health test, factor any discount into the price, and then stop worrying about degradation. In all likelihood the battery will still be well inside its useful life when the rest of the car starts showing its age.
If you want maximum longevity insurance, prefer LFP-equipped models (BYD Atto 3, MG4 Standard Range, post-2021 Tesla RWD), garage the car when possible, and charge to 80% for daily use. Do that and your battery will likely outlast the rest of the car.
People also ask
Frequently asked questions
Will my EV battery die after 10 years?
Almost certainly not. “Dead” in EV terms means below ~70% capacity, and most modern packs reach that around 12 to 15 years. The car may have other issues by then, but the battery is unlikely to be the limiting factor.
Can I drive an EV with a degraded battery?
Yes. Degradation just reduces range; it doesn’t affect performance or safety. A 70% SOH battery still delivers full power and full charging speed, and all the safety systems work as normal. You just go fewer kilometres between charges.
Does Australia’s climate damage EV batteries faster?
The hot interior and northern climates (Darwin, Perth, Brisbane in summer) do accelerate degradation versus temperate climates. Garaging the car helps a lot. Sydney, Melbourne, Adelaide and Hobart conditions are mild enough that climate alone isn’t a major factor.
