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BattGrade
For car buyers

Know the battery before you buy the car.

The high voltage battery is the biggest unknown in a used electric car. A BattGrade certificate tells you how much of its original capacity is left, how that was measured and who measured it, and you can check that it is genuine in one scan.

Verify a certificate See a sample certificate
The certificate

What a BattGrade certificate is.

A PDF that records the condition of an electric car's high voltage battery on the day it was tested. The score is calculated by BattGrade's server from the raw data read from the car, so neither the inspector nor the seller can type it in, and the certificate is digitally signed, so any change would show.

  • The State of Health (SoH), with the method behind it and an uncertainty band
  • A grade from A to F, on the same bands for every make
  • Warning signs, wherever the car provides the data
  • The name of the inspector who ran the test
  • Valid for 6 months from the day it is issued
Reading the numbers

How to read the SoH and the grade.

State of Health

The usable energy or capacity of the battery today, as a percentage of what the same battery variant offered when new. 100% is as new; the certificate never shows more than that.

The uncertainty band

Read the SoH together with its band. On the sample, 91.3% with a band of ±6 points covers 85.3% to 97.3%. Two cars whose bands overlap may be closer than their headline numbers suggest.

The method

Energy-based and capacity-based values are worked out from the car's own energy or capacity data. A BMS-reported value is the figure the car's battery management system gives, used as it is.

The grades

  • A85% and above
  • B70% to 84.9%
  • C55% to 69.9%
  • D40% to 54.9%
  • FBelow 40%

The grade comes from the SoH alone and is never assigned by hand. A B on one make means the same SoH range as a B on any other.

Read the full methodology
Warning signs

What to look for besides the grade.

These checks run only when the car provides the data. They are shown on the certificate and do not change the grade by themselves, so read them even when the grade is good.

Signs of a BMS reset

The battery management system's figures do not fit the pack's capacity or the car's mileage. A BMS reset or a pack replacement can cause this. Ask for the service history.

Uneven cells

Cell voltages that differ by more than 30 mV are marked for attention, and by more than 50 mV as poor. It can point to an unbalanced or weak module.

Insulation

Insulation resistance below 500 Ω/V is a warning, and below 100 Ω/V a failure under UN Regulation No. 100. Have the high voltage system inspected by a qualified technician.

Temperature spread

Battery temperatures that differ by more than 5 °C can point to a cooling issue or a faulty sensor.
No certificate yet?

Ask the seller for a BattGrade test.

If the car has no certificate, ask the seller to have the battery tested. The test takes a few minutes with the car switched on and writes nothing to the car. Tests are run by inspectors, dealers and fleet teams who use the BattGrade app, and the seller can send you the PDF.

When you get the certificate

  1. 1Open it at battgrade.com/verify with its QR code or ID, and look for the green banner.
  2. 2Check that the make, the model and the visible part of the VIN match the car in front of you.
  3. 3Compare the test date and the mileage on the certificate with the car today.
  4. 4Read the checks and the uncertainty band, not just the grade.
A message you can send
Hello, before we agree on a price, could you have the battery tested with BattGrade and send me the certificate? I will check it myself at battgrade.com/verify.
Covered cars

Cars that can be tested today.

Each model has its own page: the adapter, where the port is, how the test runs and how the SoH is measured.

Nissan Leaf and e-NV200
Renault Zoe
See every car on the coverage page
Verify

Check a certificate yourself.

Every certificate has a QR code and an ID. Scan the code or type the ID below to open its live record. The page checks the digital signature each time it opens, and a green banner means the data has not changed since the certificate was issued.

See a sample certificateHow verification works
Find an inspector

Want a test near you?

There is no public list of inspectors yet. Tell us where the car is and which car it is, and we will reply by email.

We use your details only to answer your message. See our Privacy Policy.

Questions, answered.

No. The score is calculated and signed by BattGrade's server from the raw data read from the car. Nobody can type it in, and any change to the stored data shows on the verification page.
No. The SoH compares the battery's energy or capacity with the same battery when new. The range a car achieves also depends on the car, the weather and how it is driven.
A certificate is valid for 6 months from the day it is issued. After that it can still be verified, but it shows as expired, and the battery may have changed since the test.
It depends on the make and model. The coverage page lists every model the BattGrade app can read today.
No. BattGrade is a private company, not a government body and not an accredited test lab. What we stand behind is how the number is made: the score is calculated and signed by our server from the data read from the car, nobody can type it in or change it, and the certificate shows who ran the test.