01
Battery State of Health (SOH)
How much usable capacity the pack retains compared with when it was new. Shown as the vehicle-reported figure when the BMS exposes it; otherwise any estimate is clearly labelled as derived.
BMSDerived
Independent EV battery diagnostics in India
EV Battery Health Testing for Electric Cars
A non-invasive assessment of your electric car battery and other accessible electronic control units (ECUs) through the vehicle diagnostic interface, without opening the battery pack. Exterior, drive, service-history and Vahan checks belong to our comprehensive EV inspection.
What EV battery health means
SOH, SOC, SOE and SOP explained
Battery health is about how the pack has aged, not how full it is today. These four terms describe different things, and no single one tells the whole story.
SOH
State of Health
Long-term condition. How much capacity the battery still holds versus new. Changes slowly over months and years.
SOC
State of Charge
Short-term level. How full the battery is right now, as a percentage. Changes every time you drive or charge.
SOE
State of Energy
Usable energy remaining in kWh at this moment. Related to SOC, but it also reflects voltage and temperature.
SOP
State of Power
How much power the battery can safely deliver or accept right now. Cold, heat, low charge or faults can reduce it.
What we look at
Battery health and ECU diagnostics.
Battery indicators and accessible ECU readings, reviewed together. We separate what the vehicle reports directly from what we estimate.
- BMSVehicle-reported data
- Read from the vehicle’s battery management system (BMS). Figures such as SOH and SOC are the BMS’s own estimates, not independent capacity measurements.
- DerivedDerived estimate
- Calculated by us from other readings. Useful context, but not the vehicle’s own figure.
- ObservedTest observation
- Behaviour seen during resting, driving or charging checks, which depends on conditions on the day.
02
Battery State of Charge (SOC)
The vehicle’s estimate of how full the battery is right now, like a fuel gauge. It is not a measure of how much capacity the pack has retained over time.
BMS
03
Cell voltage balance
The spread between the highest- and lowest-voltage cell groups. A wide or growing gap can point to uneven ageing or a weak group.
BMSDerived
04
Temperature and thermal behaviour
Pack temperature sensor readings, and how they move at rest, while driving or charging, where those channels are available.
BMSObserved
05
Battery fault codes and warnings
Stored and pending battery-management and high-voltage diagnostic codes, explained in plain language with their limits.
BMS
06
Voltage and current behaviour
Pack voltage and current at rest and under demand show how the battery responds when asked for energy.
BMSObserved
07
Power capability and derating
Signs that the vehicle is limiting power or regen because of battery condition, temperature or a fault, where limits are reported.
BMSDerived
08
Performance during controlled testing
What the readings do during a controlled drive or charge session, when conditions allow one to be carried out safely.
Observed
Diagnostic coverage depends on the vehicle. Not every EV exposes every parameter listed above, and some data may only be available through manufacturer tools. Readings from other accessible ECUs are included where available. We will tell you what can and cannot be read for your vehicle before and during the assessment.
In more detail
How the assessment reads your battery.
BMS data and diagnostic access
The battery management system (BMS) monitors the pack and stores readings and fault codes. We read what the vehicle exposes through its diagnostic port. Some EVs share a lot, some very little, and some data is only available through manufacturer tools. We tell you what was and was not accessible.
Cell imbalance and why it matters
A pack is made of many cells grouped in series. If one group drifts lower than the others, the BMS may stop discharging early or charge more slowly to protect it, reducing usable range and power. A small spread is normal; a wide or unusual one deserves attention.
Voltage, current and temperature
Together these show how the pack responds to demand. Voltage that sags sharply under load, or temperatures that differ widely between sensors, can point to ageing or cooling issues worth investigating.
Diagnostic trouble codes
Stored and pending codes from the BMS and high-voltage systems reveal history a test drive cannot, including intermittent faults. A code is a clue, not a verdict; we explain what it may mean and what it does not prove.
Performance under load
Where safe and practical, readings during acceleration or regeneration show whether the vehicle is limiting power, which can signal temperature, charge-level or battery-condition constraints.
Resting, driving and charging observations
Resting readings show balance without load, driving shows response to demand, and charging shows how the pack accepts energy. Which of these we can carry out depends on the vehicle, its charge level and conditions on the day.
Limits of individual metrics
SOH methods differ between manufacturers. Cell spread depends on charge level and temperature at the time. Codes may be historic. Range depends on conditions. That is why we interpret readings together and state their limits, rather than reducing a battery to one score.
Battery assessment vs simple OBD scan
A simple scan lists stored fault codes. A battery assessment also reviews SOH where available, cell balance, temperatures, voltage and current behaviour, and puts them in context with the codes, ending in a written report with suggested next steps.
What you receive
Understanding your battery health report
These excerpts come from one inspected Tata Nexon EV. They show battery and accessible ECU findings; values and diagnostic coverage vary by vehicle. A digital report may include:
- 01
Battery SOH, when accessible
The vehicle-reported figure, shown separately from any derived estimate.
- 02
Cell voltage variation
Highest and lowest cell-group voltages and the gap between them.
- 03
Temperature observations
Returned sensor channels, plus any that need verification.
- 04
Diagnostic trouble codes
Stored and pending codes with plain-language context.
- 05
Performance findings
Behaviour seen during the checks that conditions allowed.
- 06
Detected abnormalities
Anything outside expected patterns, stated with its limits.
- 07
Recommendations
Suggested next steps, including when further workshop inspection is advisable.
Test eligibility
Which electric cars can we test?
We are building model-by-model evidence. Until a model is validated across its variants, it stays under evaluation.
Tata
- Nexon EV
- Tiago EV
- Tigor EV
- Punch EV
- Curvv EV
- Harrier EV
- Sierra EV
MG
- Comet EV
- ZS EV
- Windsor EV
Mahindra
- XUV400
- XUV 3XO EV
- BE 6
- XEV 9e
- XEV 9S
Under evaluation
Maruti Suzuki
- e Vitara
Toyota
- Urban Cruiser Ebella
VinFast
- VF 6
- VF 7
- VF MPV 7
- Limo Green
Hyundai
- Kona Electric
- Ioniq 5
- Creta Electric
Kia
- EV6
- EV9
- Carens Clavis EV
BYD
- e6
- eMax 7
- Atto 3
- Seal
- Sealion 7
Citroën
- ë-C3
BMW
- i3
- i4
- i5
- i7
- iX
- iX1
Mercedes-Benz
- EQC
- EQA
- EQB
- EQE SUV
- EQS
- EQS SUV
- G 580 with EQ Technology
- Mercedes-Maybach EQS SUV
Volvo
- XC40 Recharge
- C40 Recharge
- EX40
- EC40
- EX30
- EX90
Audi
- e-tron
- Q8 e-tron
- e-tron GT
- Q6 e-tron
Porsche
- Taycan
- Macan Electric
Jaguar
- I-Pace
Mini
- Cooper SE
- Cooper Electric
- Countryman Electric
Tesla
- Model 3
- Model Y
- Model S
- Model X
Lotus
- Eletre
- Emeya
Rolls-Royce
- Spectre
Vayve Mobility
- Eva
FAQ
Questions EV owners ask us.
The dashboard range and charge percentage do not tell you battery health. A proper check connects diagnostic equipment to the vehicle’s diagnostic port and reads what the battery management system reports, such as SOH where available, cell voltages, temperatures and fault codes, then reviews them together.
State of Health is the share of original usable capacity the battery still holds. A pack at 92% SOH can store roughly 92% of the energy it could when new. Different manufacturers calculate it differently, so it should be read alongside other data.
Often it is a reasonable figure, but it depends on the vehicle’s age, mileage, the manufacturer’s method and warranty terms. A single SOH number cannot reveal cell imbalance or stored faults, so we never judge a battery on SOH alone.
Where the vehicle exposes cell or cell-group voltages, a wide or unusual spread can indicate a weak group. It points to where further investigation may be needed; confirming a specific faulty cell usually requires deeper workshop diagnosis.
Request a battery health test or a comprehensive EV inspection before paying. Ask for access to the car with a reasonable charge level, check service records and warranty status, and review the battery readings and any stored fault codes.
Yes. A basic fault scan only lists stored codes. A battery assessment also looks at SOH where available, cell balance, temperatures, voltage and current behaviour, and interprets them together with the codes.
It varies with the vehicle, what data it makes available and whether a drive or charge observation is included. We will give you an indication for your vehicle when we confirm the booking.
No. Our assessment is non-invasive and works through the vehicle diagnostic interface. The pack is not opened.
Yes. Heat, cold, low charge, cell imbalance or faults can lead the BMS to limit power or charging speed. Readings and fault codes can help show whether such limits are present when the test is carried out.
Booking options
Request a battery health test
Share a few details. We will call to confirm whether your vehicle is supported, explain what can be read, and arrange a suitable time.
- You will receive an enquiry reference, not an appointment confirmation.
- Pricing and scope are discussed before any work begins.
- We never share your details with third parties for marketing.
Request a battery health test
Your name, phone number, state, city, vehicle make, model, variant, year of manufacture and consent are required. Only battery capacity and message are optional. Submitting this form sends an enquiry; it does not confirm an appointment.