From Equipment Prototype to Battery Production Specification

A prototype battery supports equipment development and functional testing. A production specification defines the battery configuration, operating requirements, interfaces, and acceptance criteria for manufacturing.

During development, equipment loads, dimensions, charging methods, and software configurations may change. These changes need to be documented and reviewed before the battery design is released for production.

This article explains how to convert prototype test results into documented battery requirements.

1. Separate Measurements From Requirements

A test result records an observation under specified conditions. A requirement defines the conditions and criteria that the product must meet.

For example, “the equipment operated for three hours” is a test result. To establish a runtime requirement, the operating conditions, measurement method, and acceptance criteria must be documented.

Maintain a requirements register with the following status definitions:

Assign an owner to each open item and retain the records supporting requirement approval.

2. Record Electrical Demand

Measure battery voltage and current during the equipment's operating states:

• Startup

• Normal operation

• Motor or actuator activity

• Standby

• Charging

• Shutdown

For transient loads, record current magnitude, duration, and repetition rate.

Document the equipment configuration, software version, payload, and environmental conditions associated with each test.

Component power ratings alone do not describe the electrical demand of the complete equipment.

3. Define Voltage, Current, and Energy

Document each electrical requirement separately.

The battery must meet the specified energy and power requirements. Capacity alone does not establish whether the battery can support startup or transient loads.

Document normal operating limits separately from protective disconnection thresholds.

4. Confirm Mechanical Interfaces

Prototype brackets, cables, and housings may be temporary. The production design requires controlled drawings and defined mechanical interfaces.

Include:

• Battery dimensions and tolerances

• Mounting points

• Installation orientation

• Mass limit

• Connector locations

• Cable routing

• Retention features

• Removal path

• Service clearances

Verify the battery within the intended equipment assembly.

For removable battery packs, document the insertion, locking, carrying, and removal procedures. Define any handling tests required by the project.

5. Identify Connectors and Wiring

Specify each electrical connection using documented component information.

Record:

• Connector manufacturer and part number

• Mating connector

• Pin assignment

• Polarity

• Cable type

• Cable length and tolerance

• Terminal preparation

• Strain relief

• Signal functions

Terms such as “standard connector” or “follow the sample” do not establish a controlled interface. Identify the approved components and wiring details in the production documents.

Record undecided items as open requirements.

6. Document BMS Functions and Settings

Identify the battery management system (BMS) hardware, firmware, and configuration.

Define the required functions, including:

• Voltage, current, and temperature monitoring

• Charge and discharge control

• Protection thresholds and delays

• Fault recovery

• Cell balancing behavior

• Sleep and wake-up conditions

• Fault reporting

• Communication-loss response

If the BMS settings are programmable, specify the configuration procedure and production verification method.

Record firmware identifiers and revisions that affect battery operation.

7. Prepare the Communication Specification

If the battery exchanges data with the equipment, document the communication interface.

Include:

• Electrical interface

• Communication settings

• Commands, messages, or register addresses

• Units and scaling

• Byte order

• Transmission intervals

• Timeouts

• Fault definitions

• Command permissions

• Version handling

Test communication with the intended host equipment. Include checks for missing messages, invalid data, communication interruptions, and system restarts.

A successful demonstration does not establish that all specified communication conditions have been verified.

8. Approve the Charging Arrangement

The charger used during development may differ from the equipment specified for production.

Document the charging requirements:

• Charger model or electrical requirements

• Output voltage and tolerance

• Charging current

• Charge termination behavior

• Temperature limits

• Connector and polarity

• Communication requirements

• Fault response

If the equipment operates while charging, document the power path and charging control logic.

Validate the intended battery, charger, and equipment configuration as part of the project test plan.

9. Define Environmental Conditions

Specify the environmental conditions for operation, charging, storage, and handling.

Depending on the application, requirements may include:

• Temperature

• Moisture

• Condensation

• Dust

• Cleaning agents

• Vibration

• Mechanical shock

• Airflow

• Heat from adjacent components

If an ingress protection rating is required, identify the tested assembly and connector condition.

Enclosure materials and seal selection alone do not establish the ingress protection rating of the assembled product.

10. Establish the Validation Plan

For each requirement, define a verification method and acceptance criterion.

Record the sample configuration, test equipment, and test conditions.

If a test sample differs from the proposed production design, document the differences and assess whether additional verification is required.

11. Define Production Checks

Design validation evaluates whether the design meets its requirements. Production checks assess manufactured units against the approved inspection and acceptance plan.

Depending on the battery application, checks may include:

• Visual inspection

• Polarity verification

• Pack voltage measurement

• Configuration verification

• Communication checks

• Selected protection-function tests

• Insulation-related measurements

• Capacity or functional tests

Define test coverage, sampling methods, equipment, and acceptance criteria.

Destructive tests require a documented sampling and evaluation plan.

12. Control Production Documents

Manufacturing should use approved and revision-controlled documents.

Assign an identifier and revision to each document.

Review and resolve conflicting information before production release.

13. Review Compliance Documentation

Identify the documentation required for the application, destination markets, and transport arrangements.

Confirm that the assessed battery construction matches the production design.

Changes to cells, electrical configuration, protective components, or enclosure design may require review by the relevant laboratory or certification body.

Battery documentation does not automatically cover the complete equipment or every product variant. Determine the applicable scope for each product configuration.

14. Establish Change Control

Use a documented process to review proposed design or manufacturing changes.

Examples include:

• Cell substitution

• Connector replacement

• BMS revision

• Firmware update

• Protection-setting change

• Insulation change

• Enclosure modification

• Manufacturing-location change

For each change, record:

1. The proposed change

2. The reason for the change

3. The affected requirements

4. The required verification

5. The approval responsibilities

6. The implementation date

Update the relevant documents and identify affected production batches where applicable.

15. Define the Purpose of a Pilot Build

A pilot build can be used to evaluate assembly instructions, inspection procedures, and production records before the planned manufacturing release.

Record:

• Assembly issues

• Component discrepancies

• Test failures

• Document corrections

• Approved rework

• Open actions

Define the pilot build acceptance criteria before assembly begins.

A pilot build does not establish field service life unless service-life assessment is included in the test program.

16. Agree on Traceability Records

Define which records must be retained and which documents must accompany shipments.

These records may include:

• Serial number

• Component batch references

• Manufacturing date

• Hardware revision

• Firmware revision

• Inspection results

• Packaging information

• Applicable reports or declarations

Specify record retention periods and access arrangements.

A serial number supports traceability when it is linked to the relevant manufacturing and inspection records.

Production Release Checklist

Before production release, confirm that:

• Electrical requirements are approved.

• Mechanical interfaces are documented.

• Components are identified.

• BMS settings and firmware are approved.

• Charging and communication have been validated.

• Acceptance criteria are defined.

• Compliance documentation has been reviewed.

• Labels, instructions, and packaging are approved.

• Change-control responsibilities are assigned.

• Open issues have documented dispositions.