What is the state of health of a battery and why must it be included?

State of health: how much battery capacity remains

State of health (state of health, abbreviated SoH) is a measure that indicates how much of the original capacity and performance of a battery remain, compared to when that battery was new. A battery that has just been produced has an SoH of (almost) 100%. As a battery is used and ages, that percentage decreases: less energy can be stored, and the battery delivers less power than at delivery. The SoH thus indicates something about the remaining utility value at a given moment, regardless of how old the battery is in years.

That information is in the digital product passport for a reason. Article 14 of Regulation (EU) 2023/1542 (Battery Regulation) addresses information about the condition and expected life of a battery, and Annex XIII lists the data that must appear in the battery passport. SoH falls into that type of data: it makes the condition of a specific battery traceable for those who need to act on it, for example at sale, reuse or recycling.

Which battery types this applies to, and what it is not

This topic concerns the battery types for which the digital passport becomes mandatory: EV batteries, batteries for light mobility means such as e-bikes and scooters, and industrial batteries above 2 kWh. For smaller batteries, such as individual cells in consumer electronics, there is no obligation for a passport and therefore no obligation to track SoH in that form.

It is also important to clarify what SoH is not. It is not a guarantee and not a promise about how much longer a battery will last: it is a snapshot of the measured or calculated condition at a specific point in time. It also says nothing about safety in itself, although in practice a low SoH often correlates with other signals about the state of a battery. And it is not a fixed figure that is set once and never changes again — the value should change along with the use of the battery.

From 18 February 2027, with Article 77 as the basis

The obligation to maintain a digital battery passport — and with it also to track data such as SoH — will apply from 18 February 2027, as laid down in Article 77 of the Battery Regulation. Until that date, there is no legal obligation to have a passport with this data. Anyone who starts tracking SoH data now does so on their own initiative, in anticipation of the obligation. For the exact manner in which the SoH must be measured or calculated, and with what frequency it must be updated, no detailed regulation is included in the sources consulted here; anyone who wants certainty on this should consult the full text of the Regulation and any implementing acts that follow.

What this means for anyone placing a battery on the market

Anyone who imports or assembles batteries that will fall under the obligation can follow the following sequence. First: check whether the battery falls into one of the categories for which the passport is mandatory — EV, light mobility means, or industrial above 2 kWh. Then: check with the manufacturer of the cells or battery pack which data on capacity and condition are already available, and whether there is a method to track or calculate the SoH during the battery's life. Next: document how that data is collected and where it comes from, so that it can be included when assembling the passport. And finally: arrange a way to update the SoH as soon as the battery is in use, rather than only setting an initial value. For those who prefer not to set up this process themselves, it is also possible to provide the data to a party that assembles and hosts the passport.

Where this is set out: Article 14 and Annex XIII

This information can be traced back to two places in Regulation (EU) 2023/1542. Article 14 governs the obligation to provide information about the condition and expected lifespan of a battery. Annex XIII lists the data that must be included in the battery passport, and state of health is part of that list. For the precise wording and any further technical specifications, the full text of the regulation is the appropriate source.

Anyone wishing to check now which data on the condition of a battery are available and how they can be supplied for a future passport can start doing so before the obligation comes into force — this saves time as 18 February 2027 approaches.

What this is based on

The Regulation itself is on EUR-Lex. We refer for each statement; you need not believe us.

What you need to do concretely

The state of health of a battery, often abbreviated to SoH, indicates how much capacity a battery still has compared to its original, new state. A battery that after use still has 85% of the original capacity has a SoH of 85%. This figure says something about how far a battery has depreciated in technical terms, regardless of how old it is in years. Two identical batteries produced on the same day can have a very different SoH after three years of use, depending on how and where they have been used.

For the digital battery passport, this data is important because the passport is not only intended to show what a battery was at delivery, but also to say something about the condition and expected lifespan during the entire period of use. This is set out in Article 14 of Regulation (EU) 2023/1542 (batteries regulation), which deals with information on the condition and expected lifespan of a battery, and is further elaborated in Annex XIII of that regulation, which lists which data must be included in the battery passport.

What is expected of you

Including the state of health as passport data

The battery passport contains a field for the state of health of the battery. For an importer or dealer of e-bikes, scooters or industrial batteries, this means that in addition to the fixed data on origin and composition, data must also be included that changes over time. This requires a different setup than a passport that is only filled in at delivery and then remains unchanged. For a company of this size, this usually means thinking about where the SoH measurement comes from: from the battery management system of the battery itself, from a diagnostic tool during maintenance, or from a periodic check by a workshop or service partner.

Distinguishing SoH from other performance data

The state of health does not stand alone in the passport. It belongs to a broader group of data on performance and sustainability, such as capacity, charging cycles and expected lifespan. For companies that have the passport compiled, it is important to know which of these data are fixed (recorded once at delivery) and which data, such as SoH, change over time. More information on which data fall into that broader group can be found on the page on which performance and durability data belong in the passport.

Ensuring the data remains traceable and up to date

Because SoH is dynamic data, there should be a time at which this data is updated. This can be during a service visit, during a trade-in, or during a periodic check offered by an importer or dealer. For companies that sell batteries and sometimes also maintain them, this means that there must be a process that records when and by whom the SoH was last measured. How often this must happen and what common practice is for this is discussed on the page on how often the data in the battery passport must be updated.

Distinguishing between who may view the SoH and who may modify it

Data that changes over time raises the question of who may view it and who may change it. For an importer who has the passport hosted, it is important to know that not every party in the chain has the same rights to this data. An end user typically has different access than a recycler or a supervisory authority. Which parties may view which data is described on the page on who may view which data from the battery passport.

Where things go wrong in practice

A common situation is that a SoH value is entered once when creating the passport and is then not adjusted again, even after years of use. The data is there, but it no longer matches the actual condition of the battery.

A different situation arises when a company has the SoH calculated by a system that does not measure consistently, for example because different battery models each use their own, non-comparable measurement method. For a company that sells multiple brands or types, this results in a passport in which the figures are difficult to compare side by side.

It also happens that a trader or importer does maintain the SoH internally, for example in their own inventory or service system, but forgets to transfer that data to the passport itself. The passport and the internal administration then diverge.

A fourth situation is that a company leaves it unclear who is responsible for updating the SoH after sale: the original importer, the selling shop, or the party carrying out the maintenance. Without a documented agreement, the data then remains with no one in control.

A fifth situation is that the distinction between SoH and other related concepts such as remaining lifespan or number of charge cycles is not clearly made, so that in communication with the customer or in the passport itself, concepts are confused that are not the same.

What you can record

A fixed measurement method for the state of health, so that values between different battery types and suppliers remain comparable.
An agreement on who in the chain (importer, seller, service partner) is responsible for updating the SoH after delivery.
A moment or occasion on which the SoH is reviewed, for example during maintenance, trade-in or a periodic inspection.
An overview of which sources (battery management system, diagnostic equipment, service report) provide the SoH value and how that source is documented.
A documented link between the internal inventory or service system and the data as it appears in the passport, so that both align with each other.
Clarity on how the SoH relates to other data in the passport, as can be read on the page about which data exactly must be included in the battery passport.

This is not legal advice. This page provides general information about the legislation that this platform covers. We do not know your situation. If in doubt about your own case, consult a lawyer or the competent supervisory authority.

Written with AI based on the sources above, checked by a human on 2026-08-22. Is something wrong? Let us know — corrections take priority.