There is no universal annual pass mark
The useful question for a used car is not whether its age matches a generic degradation percentage. It is whether the installed battery has been assessed with an appropriate method, whether the result is consistent with the records, and whether its usable energy meets your needs.
Age, chemistry, usage and charging conditions can affect energy retention. A fleet average describes the vehicles and method in that dataset; it does not establish the condition of this car. Without a relevant dataset and individual evidence, assigning a model-specific “normal” curve would create a number that looks more certain than it is.
Calculate loss against the same usable baseline
An illustrative decrease from 60 to 54 kWh is a loss of 6 kWh, or 10% of the original usable capacity. Spread across five years, the arithmetic average is two percentage points of original capacity per year. It does not show when the loss occurred.
A change from 90% retention to 88% retention is two percentage points, not a 2% relative change. Relative to the earlier retained capacity, the reduction is about 2.22%. State which comparison you mean, especially when reading headlines or comparing annual reports.
Decide whether the measurements are comparable
Before interpreting a change, check the test method, denominator, installed pack and test conditions. Keep a new-car gross rating out of a usable-capacity comparison. Note pack replacements and ask the test provider whether software or procedure changes affect comparability.
A lower dashboard range after colder weather is not a repeat capacity test. The first step is to examine consumption and operating conditions. If a capacity result changes materially without an explanation, or the car develops warnings or charging interruptions, ask the manufacturer or a qualified inspector to investigate.
| Keep with every result | Why it matters |
|---|---|
| Date and odometer | Places the result in the car’s history |
| Pack and usable baseline | Prevents comparisons between different batteries or definitions |
| Provider and procedure | Reveals changes of measurement method |
| Conditions and service notes | Helps explain changes before attributing them to ageing |
Translate the capacity difference into your route
With an 80% departure charge and 10% arrival reserve, a 60 kWh battery provides a 42 kWh driving window. A 54 kWh battery provides 37.8 kWh. At the same assumed 20 kWh/100 km, the respective planning ranges are 210 and 189 km.
The 21 km difference may matter greatly on a 200 km leg without reliable charging and much less on a short commute with charging at home. This is a better use of the capacity result than treating every battery below an arbitrary percentage as unsuitable.
Keep warranty, present condition and future life separate
A warranty threshold is a contractual condition assessed under particular terms. It is neither a universal definition of good condition nor a promise of a particular driving range. Check the original contract and the authorised assessment process for the car’s market.
Do not extend the five-year arithmetic average into an exact failure date. The degradation calculator describes the interval and values you enter. Use it to compare documented capacity and then stress-test the journeys you need, while treating any repair or warranty decision as a separate question.
Put the explanation to work
Use your own vehicle information, check the assumptions and see the calculation.
Battery Degradation →EVVerity estimates are informational and are not a substitute for a professional battery diagnostic or pre-purchase vehicle inspection.
Sources & editorial basis
- US Department of Energy — batteries for electric vehicles
- Tesla Model 3 manual — Battery Health and the optional test
Source list reviewed 2026-10-26. Additional guidance carries its own review date. Practical checklists and worked examples are EVVerity editorial guidance. Read our methodology.
Related reading
- EV Battery Health Tests: Methods, Reports and Limitations
- EV Battery Health Test Cost in the UK: Dated Price Examples
- EV Battery SoH Meaning: State of Health Explained
Apply this to a model
Check the model’s battery references, charging equipment and viewing checklist. Match the year and original market to the car you are considering.