What is the SOH of an electric vehicle battery?

SOH (State of Health) measures a battery's real capacity as a percentage of its original capacity. A new battery starts at 100%. This rate decreases over the years and charge cycles, at an average rate of 2.3% per year according to Geotab data covering 22,700 electric vehicles.

What SOH is considered good for a used electric vehicle?

An SOH above 85% is satisfactory. Below 80%, range loss starts to be noticeable in daily use. Below 75%, the battery is critical: this is generally the threshold that triggers the manufacturer's warranty, which then requires the battery to be repaired or replaced.

How do I get the SOH of my electric vehicle?

Three options exist: the manufacturer's customer portal (Renault offers a paid battery certificate for connected vehicles), an authorised workshop, or a diagnostic device plugged into the vehicle's OBD port. Fleet managers can also use telematics platforms such as Geotab for real-time SOH monitoring across their entire fleet.

Can a battery's SOH improve?

No. The degradation of a lithium-ion battery is irreversible under normal usage conditions. Good charging practices, such as favouring slow overnight charging, limiting daily charge to 80% and avoiding repeated fast DC charging, can slow this degradation but not reverse it.

Electric Battery SOH: Definition and Calculation

Q: Does SOH affect the value of a used electric vehicle?

Yes, directly. A degraded battery reduces range and therefore the vehicle's market value. In the used car market, SOH is set to become as important a valuation criterion as mileage, particularly with the arrival of the mandatory European battery passport in February 2027.

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Electric Battery SOH: Definition, Interpretation, and How to Get It

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Updated on 16/06/2026

SOH measures a battery's real capacity as a percentage of its original capacity.
A new battery starts at 100%. It loses an average of 2.3% per year according to Geotab data on 22,700 vehicles.
Below 75%, the battery is critical. The manufacturer's warranty may apply.
Three ways to obtain the SOH: manufacturer's customer portal, OBD diagnostic, telematics platform.
From February 2027, the European battery passport makes this information accessible to all.

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An electric car runs on a lithium-ion battery. This battery naturally and inevitably loses capacity over time. As a result, the vehicle's real-world range decreases, and so does its value. To objectively measure this phenomenon, an indicator exists: the SOH (State of Health). How to interpret it, how to obtain it, and why it matters, whether you're buying a single vehicle or managing an entire fleet.

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SOH: The benchmark indicator for battery health

SOH is expressed as a percentage. It measures the ratio between the battery's actual capacity and its original capacity. A new battery shows 100%. This rate decreases with time and charge cycles.

According to a Geotab study of 22,700 electric vehicles from 21 different brands, the average degradation rate reaches 2.3% per year — a slight increase compared to previous years, mainly due to increasing reliance on DC fast charging.

A practical example: a 52 kWh battery with a 92% SOH has a residual capacity of 47.8 kWh (52 × 0.92). The real-world range is reduced proportionally.

Good to know: manufacturer's warranty. The battery is typically guaranteed for 8 years or 160,000 km (conditions vary by brand). If the SOH drops below a defined threshold, 70 to 75% depending on the manufacturer , the manufacturer is required to repair or replace the battery.

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Table: How to interpret your battery's SOH

SOH	Condition	Remaining range	What it means in practice
100%	New	100%	Original capacity, maximum performance
90 – 100%	Excellent condition	90 – 100%	Normal degradation. Fully reliable vehicle
80 – 90%	Good condition	80 – 90%	Slight range loss, imperceptible in daily use
75 – 80%	Acceptable	75 – 80%	Worth monitoring. Resale value and residual value start to be affected
< 75%	Critical	< 75%	Loss of a quarter of the original range. Manufacturer warranty can be activated

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How to get your battery's SOH?

SOH is calculated from the data of the Battery Management System (BMS), the onboard system that continuously monitors the battery's condition. This data remains largely inaccessible without a dedicated tool, and no legal obligation yet compels manufacturers to provide it.

Through the manufacturer. Renault allows users to generate a battery certificate from their customer area. This is a paid service, reserved for connected vehicles. Other manufacturers provide this information at authorized workshops.

Via an OBD diagnostic tool. A device connected to the vehicle's OBD port reads BMS data and produces an independent diagnosis. Moba offers this type of solution, including the issuance of a battery health certificate.

Via a telematics platform (for fleet managers). Solutions such as Geotab enable real-time SOH tracking across an entire fleet, with automatic alerts as soon as a vehicle crosses a critical threshold. Each vehicle is managed according to its actual range. Battery replacements are proactive, not reactive.

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SOH and Fleet Management: Proactive, Not Reactive

For a private individual, SOH is useful when buying or reselling. For a fleet manager, it's an operational management tool.

Tracking the SOH of each vehicle allows you to:

anticipate battery replacements before they become urgent
assign vehicles according to their actual range — a vehicle with 80% SOH cannot perform the same routes as a new one
activate manufacturer warranties at the right time
maximize fleet value upon renewal

The stakes are rising with the evolution of regulatory obligations (initially stemming from the LOM Law): the system has shifted towards an annual incentive tax for fleets of over 100 vehicles. To avoid this, companies must achieve an electrification rate for their overall fleet of 18%, a threshold that will rise to 25% in 2027 and then to 48% in 2030. Precisely managing battery SOH becomes an absolute operational necessity to optimize vehicle rotation and control total cost of ownership (TCO).

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European Regulation: The 2027 Turning Point

The EU Regulation 2023/1542 mandates a mandatory battery passport starting in February 2027. This digital document, accessible via a QR code affixed to each battery, will trace its entire lifecycle: material origin, charge history, and state of health.

As of this date, SOH data must be made transparent and easily accessible by users and professionals. This step follows the introduction, in February 2026, of the first carbon performance classes (A to E) for batteries.

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How to Preserve Battery SOH?

The degradation rate directly depends on usage conditions. According to Geotab data, the increasing reliance on DC fast charging partially explains the rise in degradation rates observed in recent years. The main accelerating factors:

high-power direct current (DC) fast charging
regular charging cycles to 100%
repeated full discharges
prolonged parking without intermediate charging
exposure to extreme temperatures, both cold and hot

Prioritizing slow charging (AC, ideally overnight), limiting daily charging to 80%, and avoiding extreme cycles are the most effective ways to slow down long-term degradation.

Also read: How to preserve my electric car battery?

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In summary

SOH is the indicator that measures the actual health of an electric vehicle battery. It decreases by an average of 2.3% per year, becomes critical below 75%, and determines both the vehicle's range and its market value. Difficult to obtain today without a dedicated tool, it will be made accessible to everyone via the European battery passport, mandatory in February 2027. For those managing a fleet of vehicles, it's already an indicator to monitor in real-time, not to discover too late.

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FAQ

What is the SOH of an electric battery?

SOH (State of Health) measures a battery's actual capacity as a percentage of its original capacity. A new battery starts at 100%. This rate decreases with years and charge cycles, at an average rate of 2.3% per year according to Geotab.

What SOH is considered good for a used electric car?

An SOH above 85% is satisfactory. Below 80%, the loss of range starts to become noticeable. Below 75%, the battery is critical, which is usually the trigger threshold for the manufacturer's warranty.

How to check your battery's SOH?

Three options: the manufacturer's customer portal (Renault offers a paid battery certificate), an authorized service center, or a diagnostic tool connected to the OBD port. Fleet managers can also use telematics platforms like Geotab for real-time monitoring.

Does SOH affect the value of a used electric vehicle?

Yes, directly. A degraded battery reduces range, and therefore the vehicle's market value. In the used car market, SOH is set to become a valuation criterion as significant as mileage.

Can SOH improve?

No. The degradation of a lithium-ion battery is irreversible under normal use conditions. Good charging practices can slow down this degradation, but not reverse it.

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