Dynamic Battery Data: What Your BMS Must Report

Why the Battery Passport Is Incomplete Without Dynamic Data

Most discussions around the digital battery passport focus on static manufacturer data: rated capacity, voltage, material composition, carbon footprint. These values are fixed the moment the battery leaves the factory. But a battery is not a static product: it ages, loses capacity, and shifts its performance profile with every charge cycle.

Dynamic data is especially relevant for stationary storage, more on the battery passport for energy storage page.

The EU Battery Regulation (EU) 2023/1542 and DIN SPEC 99100 acknowledge this reality: The battery passport must contain not only manufacturer specifications but also dynamic condition data that changes over the battery's lifetime. State of charge, capacity fade, cycle count, temperature extremes: these values typically come from the Battery Management System (BMS) and must be documented in the passport.

In practice, many battery passport tools ignore this part entirely. They cover the seven data categories of DIN SPEC 99100 but only address Section 6.7 halfway: static rated values are included, dynamic condition data is missing. The result is a passport that immediately stands out as incomplete during market surveillance or a second-life audit.

What the EU Battery Regulation Requires for Dynamic Data

Article 77(4) of the EU Battery Regulation (EU) 2023/1542 mandates that the battery passport must be updated throughout the battery's lifetime. Entering manufacturer data once and considering the passport complete is not sufficient.

DIN SPEC 99100 specifies this requirement in Section 6.7, distinguishing between two data areas:

• Static performance data: Manufacturer-rated values: energy, voltage, power, expected lifetime, temperature range. Captured once at production.
• Dynamic condition data: Current measurements from operation: SoC, capacity fade, cycles, efficiency, temperature extremes, internal resistance. These change continuously.

The actual legal basis for the condition values is not Article 77, however, it is Article 14. Paragraph 1 has required since 18 August 2024 that the battery management system contain “up-to-date data for the parameters for determining the state of health and expected lifetime of batteries as set out in Annex VII”. Annex VII lists those parameters one by one: for electric vehicle batteries the state of certified energy (SOCE); for stationary storage systems and LMT batteries the remaining capacity, where possible the remaining power capability and the remaining round trip efficiency, the evolution of self-discharging rates and, where possible, the ohmic resistance. Part B adds the date of manufacture, energy and capacity throughput, the tracking of harmful events and the number of full equivalent cycles. These values reach the passport through Annex XIII point 4, where they are expressly accessible only to persons with a legitimate interest, not to the public.

The scope matters: Article 14(1) names only stationary battery energy storage systems, LMT batteries and electric vehicle batteries. Industrial batteries that operate safely without a connected battery management system, such as lead or nickel-cadmium batteries in UPS installations, telecom backup power or forklifts, are not covered there. The battery passport data model carries a category of its own for them, “industrial battery without BMS”. If you place such batteries on the market you need the passport, but not a stream of condition data from a battery management system that does not exist.

Both data areas belong in the passport from 18 February 2027, as far as they apply to the battery type in question; the dates are in the EU Battery Regulation timeline. For EV, LMT and stationary batteries that means a passport without dynamic condition data does not fully meet the regulation's requirements.

The Seven Dynamic Data Categories in Detail

DIN SPEC 99100 defines dynamic condition data across seven categories. Each category requires a measurement timestamp (lastUpdate) documenting when the values were last updated.

1. State of Charge & Capacity

The core of any battery assessment. Four required fields:

• State of Charge (SoC): Current charge level in percent
• Remaining Capacity: Available capacity in Ah
• Capacity Fade: Capacity loss compared to initial state, in percent
• Full Cycles: Number of completed full charge/discharge cycles

Together, these four values determine the State of Health (SoH), the most important indicator for residual value and second-life eligibility.

2. Energy & Throughput

Five fields covering the energy balance:

• Remaining Energy (kWh)
• State of Certified Energy: Percentage of remaining usable energy
• Energy Throughput: Cumulative energy charged and discharged (kWh)
• Capacity Throughput: Cumulative charge transferred (Ah)
• Power Fade: Power loss in percent

3. Remaining Power Capability

DIN SPEC 99100 requires remaining power at two defined charge levels:

• Power capability at 80% SoC (in watts)
• Power capability at 20% SoC (in watts)

The value at 80% SoC must logically be greater than or equal to the value at 20% SoC.

4. Efficiency & Self-Discharge

• Round-trip efficiency at 50% cycle life
• Remaining round-trip efficiency
• Efficiency fade
• Current self-discharging rate (%/month)
• Evolution of self-discharge

5. Temperature Extremes

Operating hours outside permissible temperature limits:

• Hours above the upper limit (idle state)
• Hours below the lower limit (idle state)
• Hours above the upper limit (during charging)
• Hours below the lower limit (during charging)

Charging hours cannot exceed total hours, a validation rule that should be enforced automatically during data entry.

6. Internal Resistance

Internal resistance increase is a key aging indicator. DIN SPEC 99100 allows measurement at three levels:

• Pack: Complete battery pack
• Module: Individual battery module
• Cell: Individual battery cell

Multiple entries with different components are supported.

7. Negative Events

Safety-relevant incidents such as deep discharge, overheating, or mechanical damage. Each event is recorded as free text with a timestamp.

Static vs. Dynamic Data Compared

To illustrate the difference:

A complete battery passport requires both halves. Capturing only static rated values completes the manufacturer documentation, but not the passport. Our step-by-step guide to battery passport creation covers the static data entry process.

BMS Integration via REST API

Manual data entry through a dashboard works for individual batteries or diagnostic reports. For fleets with hundreds or thousands of batteries, you need a programmatic interface.

DPP Hero provides a dedicated API endpoint for this:

PATCH /api/v1/products/{id}/condition

Three properties make this endpoint production-ready:

• Partial updates: Send only the fields that changed. Existing values remain untouched. Your BMS doesn't need to transmit the complete condition dataset with every update.
• Schema validation: Every API call is validated against a strict schema: value ranges, data types, and logical rules (e.g., charging temperature hours ≤ total hours) are checked automatically.
• Per-field timestamps: Each field carries its own lastUpdate timestamp. This makes it traceable when each value was last measured, even when different sensors deliver data at different times.

Additionally, DPP Hero supports data collection via share links: External partners, such as maintenance providers or second-life assessors, can enter condition data directly through a guided form, without needing their own account. To understand which data these external actors can access under the three-tier model, see our article on battery passport data access rights.

What to Look for in a Battery Passport Tool

When evaluating a battery passport tool, check specifically how it handles dynamic data:

• Is dynamic condition data supported at all? Many tools only cover the static sections of DIN SPEC 99100.
• Is there an API for BMS integration? Manual entry doesn't scale. A REST API with partial updates is essential for automated data flows.
• Are timestamps captured per measurement? A single timestamp for all fields isn't enough, DIN SPEC 99100 requires lastUpdate per data point.
• Is validation standard-compliant? Value ranges (e.g., SoC 0 to 100%), logical dependencies (charging hours ≤ total hours), and required fields should be validated automatically.
• Can external partners contribute data? Not all condition data comes from the manufacturer. Maintenance providers, recyclers, and second-life assessors need a way to submit measurements.

DPP Hero covers all of these requirements: dashboard entry with seven structured sections, a REST API with partial updates and schema validation, and share links for external data contributors. The data structure follows DIN SPEC 99100, Section 6.7. To see what a complete battery passport with static and dynamic data looks like in practice, explore our demo battery passport.

When does an update become due?

The Regulation names no interval in days or months. It ties the update to an event. Annex XIII requires the performance and durability values under Article 10(1) when the battery is placed on the market, and when its status changes. That is the actual rule: not monthly, but on every status change.

In practice you have to know the trigger, not the calendar. Build a process that adds data once a quarter and you miss the requirement in both directions: too rarely on a status change, too often during unchanged operation.

The battery status field and what it triggers

Annex XIII carries a dedicated field for the battery status, with five possible entries: original, repurposed, reused, remanufactured or waste. That field is the switch the update duty hangs on.

What matters is the legal consequence behind it: batteries prepared for re-use or repurposing, repurposed or remanufactured count as newly placed on the market. Repurpose a battery and you take on the duties of a manufacturer, passport included. For anyone running a second-life business model, that is the most important sentence in the whole Regulation.

Which level does the passport sit on: cell, module, pack?

The question arises as soon as you ship a rack or a container. The Regulation attaches the passport to the battery that is placed on the market, not to its components. Sell a pack and the pack is the battery. Sell a container holding several racks as one product and that container is the battery placed on the market.

The levels below do not disappear: the passport carries the composition, and condition data comes from the battery management system of the respective unit. What decides the number of passports, though, is the sales unit. Settle this early, because it determines how many serial numbers and how many QR codes you need.

Frequently Asked Questions

When do dynamic battery data become mandatory?

The EU Battery Regulation (EU) 2023/1542 mandates the digital battery passport from 18 February 2027. Dynamic condition data is part of the required information and must be included and updatable from that date. See our EU Battery Regulation 2027 timeline for details.

Can BMS data be transferred automatically to the battery passport?

Yes, via a REST API. DPP Hero provides a dedicated endpoint (PATCH /api/v1/products/{id}/condition) that accepts partial updates. BMS systems, IoT gateways, or maintenance software can transmit condition data directly and automatically.

Which dynamic fields are mandatory under DIN SPEC 99100?

All seven data categories from Section 6.7 are required: state of charge & capacity, energy & throughput, power capability, efficiency & self-discharge, temperature extremes, internal resistance, and negative events. DPP Hero keeps 21 individual fields for this, each with its own timestamp. Other sources count differently because they count data areas rather than individual fields.

How often must condition data be updated?

The EU Battery Regulation does not specify a fixed update frequency. However, DIN SPEC 99100 requires a lastUpdate timestamp per data point. In practice, the update frequency depends on the use case: quarterly updates may suffice for stationary storage, while EV batteries with high cycle counts may warrant monthly or event-based updates.

What happens if the battery passport contains no dynamic data?

A battery passport without dynamic condition data is incomplete per DIN SPEC 99100. During market surveillance or a second-life audit, the lack of current health data is immediately apparent. Our Battery Passport Checklist 2027 helps you systematically address all required areas.