leafA fully charged Nissan Leaf is not necessarily a healthy-battery Leaf. The charge display tells you how full the pack is now. It does not tell you how much the pack can hold compared with its earlier condition. That distinction matters whether you are keeping your car for another five years or standing on a seller’s driveway.
The short answer
To see more detail, connect a compatible OBD2 adapter and a Leaf-specific app, read the battery controller’s state of health, then interpret it alongside capacity, cell-pair voltages, temperature and driving behaviour. Leaf Pro is built for that workflow on ZE0, AZE0 and ZE1 cars. It is coming soon to iPhone and Android.
You can learn something from the car’s own capacity display without an adapter, but a broad display is not the same as a detailed cell reading. Neither method alone guarantees that a battery is fault-free.
Get the connection right first
For an iPhone, choose BLE or Wi-Fi. Android also supports Classic Bluetooth. This is where many first attempts fail: “Bluetooth OBD2” on a listing does not establish that it works with iOS. Check the exact adapter, not just the product photo.
Ask permission before plugging into someone else’s car. Park safely, locate the diagnostic socket using the vehicle manual, and connect without changing service settings. Close other diagnostic apps that might already be using the adapter. See the adapter guide for the transport differences.
Record these readings together
| Reading | Useful for | Does not establish |
|---|---|---|
| SOH | The controller’s capacity-health estimate | Remaining years of battery life |
| SOC | How charged the battery is now | How healthy the battery is |
| Ah | Charge-capacity context for that pack | A direct kWh figure |
| Cell spread | Difference between highest and lowest cell-pair voltages | A universal pass/fail diagnosis |
| Temperature | Context for the session | The complete battery’s thermal history |
Hx is another controller indicator. Keep it in the record, but resist treating a number somebody posted in a forum as a universal threshold for your battery. There is a separate SOH, Hx and Ah explanation if those abbreviations are new to you.
Use a representative drive
An idle screenshot is a starting point. A recording can show whether the same cell pair repeatedly behaves differently when demand changes. Start the recording while parked, drive normally and legally, then review it after stopping. You do not need to provoke a warning, drain the car or watch the phone while moving.
Leaf Pro’s Full Assessment records the available data and reports both findings and coverage. Coverage matters: a short recording without useful load or cell samples is not equivalent to a broader assessment. Read the assessment guide before starting.
What to do with the result
For your own car, save dated records and compare similar conditions. For a purchase, combine the readings with the test drive, vehicle history, charging checks and a qualified inspection where appropriate. A seller’s screenshot may concern a different day, a different charge level or even a different car; keep the vehicle identity and recording date attached.
A disappointing SOH figure does not automatically mean the car cannot meet your needs. Equally, a high SOH does not rule out a weak cell or another fault. Ask whether the car can perform your route with a sensible reserve, and investigate abnormal behaviour before money changes hands.
Can I check without an OBD adapter?
You can inspect the vehicle’s capacity display, service records and real test-drive behaviour. You cannot use those alone to read all 96 cell-pair voltages. If the buying decision depends on battery condition and you cannot obtain reliable readings, a specialist inspection is a reasonable next step.