Unique identifier rules: one battery, one identifier, never reused

A unique identifier is a code that identifies one individual battery and no other battery. Under Article 77, the battery passport is an electronic record for the individual battery, and the unique identifier is the key that makes the record individual rather than generic. The rules for the identifier are simple to state and demanding to operate: assign once, assign before placing on the market, never reuse, never duplicate, and keep the identifier stable across the life of the battery except where a defined linkage event creates a new identifier with a recorded link to the old one.

Simplicity in the rule and difficulty in operation is a familiar pattern in record systems. The difficulty lies in assignment discipline across production lines, suppliers and time.

When is an identifier assigned?

An identifier is assigned during production, before the battery is placed on the market or put into service, and before the data carrier that encodes it is applied to the battery. Assignment before placing matters because the passport record must exist, or be capable of being created, at the point the battery enters the market. An identifier assigned after sale, or assigned on first scan, leaves a period in which the battery exists without a record key, and history from that period cannot be attributed with confidence. The assignment event should be recorded with a date, a production reference and the model identifier, so that the identifier can be traced to the production run. A system that assigns identifiers in batches, without recording which batch a unit belongs to, creates identifiers that are unique in form but untraceable in fact.

What makes an identifier unique in practice?

Uniqueness in practice requires a namespace, a format and a control. The namespace is the set of identifiers issued by the responsible operator or the system that issues identifiers on its behalf. The format is the structure of the code: length, character set, check character or checksum where used, and the rule that distinguishes a model identifier from a unit identifier. The control is the process that prevents duplication: a central register, a sequential or random generation rule with collision checking, and a prohibition on manual re-entry of identifiers. Uniqueness cannot be checked by looking at one identifier. It can only be checked by looking at the register as a whole and confirming that no identifier appears twice and no battery carries two identifiers without a linkage record. A register check is therefore part of identifier discipline, performed at intervals and after any system change.

How is an identifier different from a serial number?

A serial number is a production number that may be unique within a model, a plant or a period, but need not be unique across the whole system. A unique identifier in the passport sense must be unique across the record system for the life of the battery, and must resolve to one record and one battery. A serial number can serve as the basis for a unique identifier where the system combines it with a manufacturer or model prefix that guarantees system wide uniqueness, and where the combination is recorded as the identifier. A serial number used alone, without that combination, risks collision when the same serial sequence is reused for a new model or a new plant. The record should state the identifier in full, as encoded in the data carrier, and should not shorten it for display in a way that creates ambiguity. Display shortening is a common source of identifier errors in workshops and recycling facilities, where a partial code is copied by hand.

What does the identifier table illustrate?

What happens when an identifier is misprinted or damaged?

A misprinted identifier is a production defect in the data carrier, not a reason to assign a new identifier silently. The battery should be held, the carrier reprinted or replaced with the same identifier, and the correction recorded in the production register. A damaged identifier on a battery in use raises a different question: the record still exists under the original identifier, but the route to it is impaired. The fallback route, such as manual entry of the identifier from marking or documentation, should be available without creating a duplicate record. A new identifier assigned to a battery in use, without a linkage record, splits the history into two records and makes the earlier history hard to find. The linkage rule is therefore strict: new identifiers are exceptional, linkage is mandatory, and the reason is recorded.

What limits apply to identifier claims?

An identifier proves that a record exists under that code. It does not prove that the battery in front of the reader is the battery to which the identifier was assigned, unless the marking, the carrier and the record agree. Identity is established by the set of checks in the identity guide, not by the identifier alone. This guide gives general educational information only and does not give legal advice for a particular battery, identifier system or transaction.