Keeping condition data current after sale
Part of a battery passport keeps changing after the battery is sold. Which data that is, which batteries it applies to, what triggers an update, and why to start with the static data.
Most of a battery passport is fixed the day the battery leaves the factory. Some of it isn't. For batteries with a battery management system, the passport also has to reflect the battery's condition as it ages, and keep doing so for its whole life (Art. 77(4)).
Which batteries this applies to
Since 18 August 2024, the battery management system of stationary storage, LMT and EV batteries must hold up-to-date data for working out state of health and expected lifetime (Art. 14(1)). Annex VII lists the parameters:
- EV batteries: certified usable energy.
- Stationary and LMT batteries: remaining capacity, remaining power, round-trip efficiency (where possible), self-discharge and ohmic resistance (where possible).
- Both: manufacture date, energy and capacity throughput, harmful events and full equivalent cycles.
Industrial batteries without a battery management system, such as lead or nickel-cadmium batteries in UPS, telecom backup, forklifts or railway signalling, still need a passport but have no condition data to stream.
What counts as dynamic data
DIN DKE SPEC 99100 separates static data (rated values, captured once) from dynamic data (measurements that change), and groups the dynamic data into seven areas:
- Charge and capacity: state of charge, remaining capacity, capacity fade and full cycles, which together give state of health.
- Energy and throughput: remaining energy, certified usable energy and power fade.
- Remaining power, at 80% and 20% state of charge.
- Efficiency and self-discharge: round-trip efficiency and how self-discharge is changing.
- Temperature extremes: time spent above and below limits, idle and charging.
- Internal resistance, at pack, module or cell level.
- Negative events: deep discharge, overheating, mechanical damage and similar, timestamped.
Each should carry the time it was last updated. This data sits in the restricted part of the passport (Annex XIII point 4), for parties with a legitimate interest such as repairers and recyclers, not the public.
When it must be updated
The regulation doesn't set a calendar. It requires performance and durability values when the battery is placed on the market and whenever its status changes between original, repurposed, re-used, remanufactured and waste, and it requires the data to stay current. How often to update otherwise is left to the responsible company. Monthly or event-based updates for EV batteries and quarterly updates for stationary storage are reasonable starting points, but they are suggestions, not rules.
Several questions are still open as of October 2026: what "periodically" means in practice, the cost, energy use and security of continuous transmission, and the act defining who has a legitimate interest.
Who updates it
The company that placed the battery on the market remains responsible for keeping it current. It can authorise others in writing (a fleet operator, a maintenance provider) to submit data, but stays answerable. When a battery is repurposed or remanufactured, whoever puts it back on the market creates a new passport linked to the original. When it becomes waste, responsibility passes to the producer, the producer responsibility organisation or the waste operator.
How to approach it
- Build the static core first. Identifiers, QR codes, chemistry, capacity, manufacturer identity and conformity documents are well defined. A small, reliable first version beats a complete one you can't keep up.
- Decide the update frequency per field, based on what each value is used for, and record the decision.
- Design for many sources. A single battery can be updated by hand; a fleet needs an interface that accepts partial updates, with validation (state of charge between 0 and 100%, charging hours not exceeding total hours) and a timestamp per value.
- Let outside parties contribute without full access to your system, for example through scoped links for maintenance providers or second-life assessors.
- Watch the Commission's guidance and the registry, and adjust as the rules settle.
FAQ
What is dynamic data in a battery passport?
Data that changes during the battery's life, such as state of health, state of charge, cycle counts, temperature extremes, internal resistance and negative events. It comes mainly from the battery management system.
How often must battery passport data be updated?
The regulation sets no fixed interval. Data must be kept current, and performance and durability values must be updated whenever the battery's status changes. The update frequency is otherwise up to the responsible company.
Does every battery need dynamic data in its passport?
No. The battery management system duty in Art. 14 covers stationary storage, LMT and EV batteries. Industrial batteries without a management system, such as lead-acid UPS batteries, need a passport without a condition-data stream.
Sources
General information, not legal advice. Checked against the sources above on 31 October 2026; the Commission is still adopting the acts that fill in the detail, so check before relying on a date.