There is no universal pass mark
Age and mileage alone do not describe the history of an individual battery. Chemistry, temperature exposure, operating conditions and the measurement method can differ. A fleet average can offer context when its vehicles and methods are documented, but it is not a diagnostic result for the car in front of you. EVVerity does not invent a normal-degradation curve from a model name.
Calculate what your evidence actually supports
If comparable usable-capacity measurements fall from 60 to 54 kWh, the observed loss is 10%. Over five years, the arithmetic average is two percentage points of original capacity per year. That calculation describes the interval you entered. It does not show that every individual year lost the same amount, or that the next five years will follow a straight line.
Check apparent changes before interpreting them
First rule out a gross-versus-net mismatch, different SoC windows, seasonal range differences or a change of test method. A range display that falls after cold weather is not, by itself, evidence of permanent capacity loss. Keep dated reports and comparable measurements so that a trend has a consistent reference. If a sudden change coincides with a warning or charging problem, seek a professional assessment.
Use the warranty as a document, not a verdict
A contractual capacity threshold is not a universal definition of a healthy battery. Being above it does not establish that a car is suitable for your trips; being below a claimed threshold does not automatically prove a valid warranty claim. Read the actual market-specific terms and obtain diagnostic evidence. Assess usable range, charging and condition together rather than relying on a single headline percentage.
Compare measurements without inventing a trend
A useful history uses comparable observations. When the method changes, record the break in the series instead of treating the next number as a continuation.
| Observation | Safe interpretation | Avoid |
|---|---|---|
| 60 to 54 kWh using comparable methods | 10% loss against the original 60 kWh reference | A precise date of future failure. |
| A lower winter range display | Range changed under different conditions | Calling the whole reduction permanent degradation. |
| A newer report after pack replacement | Evidence for the replacement pack | Joining it to the old pack’s trend without a note. |
Annual average versus year-by-year loss
A five-year change from 60 to 54 kWh averages 1.2 kWh per year, equivalent to two percentage points of the original capacity per year. It does not prove a constant annual rate. Compounding a 2% annual loss for five years instead gives about 54.24 kWh, which is a different calculation. Our degradation tool displays the arithmetic average and names its units. To assess a developing concern, compare dated evidence using the same method and ask a qualified provider to explain material changes. Neither the calculator nor a fleet headline supplies a pass/fail threshold for your car.
Before you rely on the answer
- Were the measurements made on the same pack?
- Did the measurement method or usable software window change?
- Are there operational symptoms as well as a percentage change?
Worksheets and numerical scenarios are original EVVerity editorial examples. They are not observed vehicle results or market-price data.
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 — EV batteries
- Tesla — battery health: an example of a manufacturer diagnostic
Sources checked 23 September 2026. Practical checklists and worked examples are EVVerity editorial guidance. Read our methodology.