Digital twin and product passport: where the data comes from

A maker of e-bike batteries keeps a digital twin for every model. It lists every part of the pack: the cells, the battery management board, the housing, the cables, the screws. The maker knows the design, the bill of materials and every supplier. What the cathodes of the cells are made of, how many charge cycles they survived in testing and which critical raw materials exceed 0.1 per cent by weight is not in the twin. The cell manufacturer knows that, and some of it only their materials supplier knows.

The battery passport, the version of the digital product passport (DPP) for batteries, asks for exactly this information, and every e-bike battery in the EU needs one from 18 February 2027. This article shows where that data gets stuck and how Transpareo fetches it from the supply chain.

What a digital twin does well

A digital twin is the machine-readable image of a product. In industry it has a standard form, the Asset Administration Shell (AAS), developed by the Industrial Digital Twin Association (IDTA) and standardised internationally as IEC 63278. It sorts a product’s data into building blocks called submodels, and each property points to an entry in a shared dictionary of characteristics such as ECLASS. That way every system knows that “weight” means the same thing everywhere.

How to describe a product has been answered with real care. How well the AAS fits the product passport, and what it still lacks for publishing, is covered in our article on the AAS as the foundation of the product passport.

The bottleneck lies before it. A twin holds what it is given, and it cannot go and collect anything. Getting trustworthy, current and consistent data from many suppliers is the real work, and that is where Transpareo comes in.

Where the data gets stuck

Seven gaps show up clearly in the battery, and they are the same in other industries.

1. The sub-suppliers. A twin assumes that everyone involved provides their data digitally. Many small and medium-sized enterprises (SMEs) run no Asset Administration Shell and keep no structured master data; their information sits in PDFs, Excel sheets and tables exported from their enterprise resource planning (ERP) system. The cell manufacturer can answer, but only their own supplier knows the composition of the cathode material.

2. The language of the data. For the weight of the cell one supplier writes “Weight”, the next “Net Weight”, the third “Mass”, the fourth “Product Weight”, one in grams, one in kilograms. A person sees the same field, a machine sees four. Shared dictionaries and the IDTA’s submodels solve this once every supplier uses them, and that is often where it falls down.

3. The bill of materials. A battery pack consists of several hundred parts, they contain thousands of materials, and tens of thousands of process values lie behind making them. Every level of the bill of materials multiplies the amount of information, and the IDTA has described a submodel of its own just for bills of materials spanning several levels.

4. Trade secrets. Recipes, process parameters, purchase prices, sources of supply and material blends are things no supplier likes to hand over. The cell manufacturer guards the blend of their cathode material, and naming your own suppliers makes you replaceable. Questions like these often go unanswered.

5. Time. A cell’s carbon footprint changes as soon as the plant switches to another energy source; guarantees of origin and certificates expire, declarations of conformity are renewed. Under the EU Ecodesign Regulation (ESPR) the data in the passport must be accurate, complete and up to date. A twin therefore accompanies a product through its whole life and needs constant upkeep.

6. The interfaces. Beside the Asset Administration Shell, other standards describe a product too: the Digital Twins Definition Language (DTDL), OPC UA for machine data, GS1 EPCIS for events in the supply chain, the Catena-X data space, product lifecycle management (PLM) systems and SAP’s data models. If the cell manufacturer keeps their data in SAP and the pack maker keeps the twin in an Asset Administration Shell, it takes a translation, and with every translation a value can lose its meaning.

7. Responsibility. Creating twins, providing interfaces and exchanging data work well today. The harder question is who vouches for a value being right. The cell manufacturer supplies a carbon footprint: does the pack maker check it, an auditor, an authority or a certification body? On responsibility the Batteries Regulation gives a clear answer: the economic operator placing the battery on the market ensures that the information is accurate, complete and up to date. In our example that is the pack maker, including for values they never measured themselves.

The overview sums up what each gap means for the passport and what Transpareo does about it.

Problem	Effect on the passport	How Transpareo solves it
Sub-suppliers without systems of their own	Information is missing, the passport stays incomplete	A request by link, answered in the browser with no account; every tier passes on what it does not know
Different names and units	Values get mixed up or converted wrongly	Everyone answers the same fields of your passport, units included; the templates name the term from a public dictionary
Bills of materials with thousands of parts	The effort grows with every level	In part: components with share and country of origin, described once and reused in every passport; the full bill of materials stays in the PLM system
Trade secrets	Questions go unanswered	Only what you tick is asked; whom a supplier asks in turn stays with them; every field has its own access tier
Values that go out of date	The passport shows an old state	Documents with their validity; before expiry a reminder and, for a document that came through a request, a new request to the supplier; then a new, signed version
Separate data worlds	Every translation costs effort and can lose meaning	In part: data arrives through the API or as a spreadsheet, with no dedicated connector for DTDL, OPC UA or SAP; publishing uses open formats, events as GS1 EPCIS
Unclear responsibility	Nobody vouches for a value	Every tier checks the tier below and passes values on under its own name; the origin of every value stays on record, every version is signed

Our assessment: most of the trouble lies with the sub-suppliers and with the question of who vouches for a value. The language of the data and trade secrets come next, the interfaces weigh less, and the modelling in the Asset Administration Shell itself causes the least.

The Asset Administration Shell settles how to describe product data. How to obtain it is decided in the supply chain.

That is where Transpareo works: on how the information from the supply chain reaches you, checked and with names attached.

Every tier answers on their phone

With Transpareo Upstream you ask the cell manufacturer straight from your workspace. They get a link and answer in the browser, on a phone or a computer, with no account, no app and no Asset Administration Shell of their own, and they upload their test reports as files along the way. What they do not know, they pass on to their materials supplier, who can pass it on in turn, as deep as the chain goes.

Whatever your passport still lacks is already ticked in the request. Before the deadline Transpareo reminds the suppliers by email. How such a request travels through four businesses is shown in our article on requests across several tiers of the supply chain.

Everyone answers in your fields

The cell manufacturer answers your passport’s fields, each in the form that suits it: the chemistry from a fixed choice, a weight with its unit, a country from a list. For batteries Transpareo comes with a template whose fields follow the mandatory information of the Batteries Regulation, with fixed values, units and the term from a public dictionary.

Because everyone answers the same question, there is no reconciling “Weight” with “Mass”. In the published passport “kg” becomes an internationally standardised unit code. Why every term in the passport sits in a public dictionary is explained in our article on the dictionaries of the product passport.

A supplier who would rather send a spreadsheet sends a spreadsheet: you import it, and Transpareo shows which mandatory fields are still missing. Your ERP, your PLM system or your Asset Administration Shell delivers through Transpareo’s application programming interface (API); you decide once which element goes into which field. Data from DTDL, OPC UA or SAP arrives the same way, since Transpareo has no dedicated connector for them.

What the supplier keeps to themselves

The cell manufacturer need not tell anyone where they buy their cathode material. When they pass your questions on, they decide whether the request shows your brand or opens under a neutral address. You see how many requests were passed on, and never to whom. Why that is exactly what makes the answers possible is set out in our article on your suppliers’ sources of supply.

In the passport every field has its own access tier: public, on request, for parties with a legitimate interest, or for authorities only. Every field is signed on its own, so every value a reader gets to see carries the manufacturer’s seal, even while the others stay hidden from them.

When a certificate expires

You keep certificates, declarations of conformity and test reports in Transpareo with their issuer, number and validity, and Transpareo shows you which of them are about to expire. When a document came from a supplier through a request, Transpareo asks them for the new version on its own before it expires. When you upload the renewed version, you see which published passports show the document. Once you confirm, each of them gets a new, signed version. Earlier versions stay available, with the document that applied at the time.

Values that change during use, such as a battery’s state of charge or cycle count, sit in a separate, separately signed document that can be updated without issuing the passport again.

A name for every value

Whether the cycle count from the cell manufacturer’s test is right is shown by their test report; where in doubt an auditor checks it. Transpareo makes visible who vouches for each value.

Every tier checks the answers from the tier below, accepts a value, corrects it or sends it back, and passes on what it accepts under its own name. Each answer arrives with you as a proposal that you accept field by field, and the product’s history shows, years later, which value came from whom. Every published version carries two seals, yours as issuer and ours, and every reader checks them in their own browser.

A passport cannot prove that a value is right. It can show who vouches for it.

With Transpareo the pack maker sees for every value how it reached them, and can show it to anyone who asks.

Components you recognise

The same cell goes into several packs. In Transpareo you describe such a component once, and a request can be about the component itself, so the cell manufacturer answers for the cell directly. Every passport lists it with its share and country of origin and points to exactly the signed version that applied when it was published. The full bill of materials across every level stays in the PLM system or the Asset Administration Shell, where it is maintained.

Copy or reference

Data spaces such as Catena-X take a thoughtful approach: every participant holds their own data and shares it when needed, with rules on who may use it for what. For ongoing exchange between connected companies that works well.

A passport also needs a fixed state. What a market surveillance authority reads in a few years’ time has to be exactly what was signed today, even if the supplier’s server no longer exists by then. That is why Transpareo keeps what you accepted, signed and in versions, and we have described separately how a product passport survives even an insolvency.

What this means for the battery

The twin goes on describing the pack as precisely as before. The bottleneck lies before it, in the information from the supply chain, and that is the part Transpareo takes on: the cell manufacturer’s information reaches you in your fields, checked at every tier and with names attached. Once the information is at hand, the passports are published in Transpareo within a few minutes.

What takes time is the gathering. Which information a battery passport requires at the start is set out in our overview of the mandatory data in the battery passport. Whoever sends the first request to their cell manufacturer today gains the months a supply chain needs to answer.