Battery Pack Design Validation: Electrical, Thermal and Mechanical Tests

Battery pack design validation is part of custom lithium battery development. Before a battery pack enters mass production, its electrical performance, thermal behavior, mechanical structure, and Battery Management System (BMS) functions need to be evaluated according to the project specifications.

For OEM and ODM applications such as electric bicycles, AGVs, AMRs, service robots, industrial equipment, and energy storage systems, battery packs are developed according to specific voltage, capacity, current, installation, and environmental requirements.

Battery pack validation involves design review, prototype inspection, functional testing, and equipment integration evaluation.

This article explains the main aspects of battery pack design validation, including electrical testing, thermal evaluation, mechanical testing, BMS verification, and prototype approval.

1. What Is Battery Pack Design Validation?

Battery pack design validation is the process of evaluating whether a battery pack meets its defined technical requirements under specified test conditions.

Validation activities may include engineering calculations, design reviews, prototype inspection, functional testing, and application-specific evaluation.

The process covers several areas:

• Electrical performance

• Charging and discharging behavior

• BMS protection functions

• Temperature monitoring

• Heat generation and dissipation

• Mechanical dimensions

• Enclosure structure

• Connector integration

• Environmental conditions

• Equipment compatibility

The validation scope depends on the battery application, electrical specifications, mechanical design, and applicable standards.

For custom battery packs, test procedures and acceptance criteria should be established according to the approved project requirements.

2. Electrical Testing for Lithium Battery Packs

Electrical testing evaluates battery operation under specified charging and discharging conditions.

It also verifies electrical connections, protection circuits, and communication interfaces.

Battery Voltage Verification

Voltage inspection confirms whether the battery pack and individual series-connected cell groups meet the specified voltage requirements.

Inspection items may include:

• Total pack voltage

• Individual cell group voltage

• Voltage polarity

• Voltage measurement accuracy

• Cell group voltage differences

For example, a 16S LiFePO4 battery pack has a typical nominal voltage of 51.2V when using cells rated at 3.2V nominal voltage.

The actual voltage during charging and discharging depends on the battery's state of charge and cell specifications.

Battery Capacity Testing

Capacity testing evaluates the amount of electrical charge delivered by the battery under defined discharge conditions.

The test procedure generally specifies:

• Charging method

• Charging termination conditions

• Discharge current

• Discharge cutoff voltage

• Ambient temperature

• Rest periods where required

Battery capacity is commonly expressed in ampere-hours (Ah).

Battery energy is expressed in watt-hours (Wh) and can be determined by integrating voltage and current over the discharge period.

Test results should be evaluated against the approved specifications and testing conditions.

Continuous Discharge Testing

Continuous discharge testing evaluates battery operation at the specified continuous current.

Testing may include monitoring:

• Battery voltage

• Discharge current

• Cell temperature

• BMS temperature

• Connector temperature

• Protection status

For example, a custom industrial battery pack specified for 50A continuous discharge may be evaluated at the agreed current and ambient temperature.

The test duration and acceptance criteria should be defined in the project test plan.

Peak Discharge Current Testing

Some battery applications require short-duration current peaks during acceleration, lifting, or motor startup.

Applications include:

• AGVs

• AMRs

• Service robots

• Electric motorcycles

• Industrial machinery

Peak current testing evaluates battery operation during specified current pulses.

The test procedure should define peak current, pulse duration, repetition conditions, and acceptance criteria.

Battery cells, BMS, busbars, wiring, and connectors should be evaluated according to the electrical requirements.

Charging Performance Testing

Charging verification evaluates battery operation according to the specified charging requirements.

Testing may include:

• Charging voltage

• Charging current

• Charging termination behavior

• Cell group voltage monitoring

• Temperature monitoring

• Charger compatibility

• BMS charging protection

The charging procedure must follow the selected cell specifications and approved battery design.

3. BMS Functional Testing and Protection Verification

The Battery Management System monitors battery conditions and provides electrical protection functions according to its hardware and software configuration.

BMS validation is part of custom battery pack testing.

Overcharge Protection

Overcharge protection testing verifies that the BMS responds according to the defined cell voltage protection thresholds.

The test procedure should also evaluate the configured recovery conditions.

Over-Discharge Protection

Over-discharge protection testing evaluates the BMS response when cell voltage reaches the specified discharge protection threshold.

Validation includes checking the protection threshold and recovery conditions.

Overcurrent Protection

Overcurrent protection testing evaluates the BMS response to current conditions outside the defined operating limits.

The test scope depends on the battery's continuous current rating, peak current requirements, and protection settings.

Short-Circuit Protection

Short-circuit protection testing evaluates the response of the battery protection system under specified fault conditions.

Testing must follow an approved procedure using appropriate test equipment and safety measures.

Uncontrolled short-circuit testing must not be performed.

Cell Balancing Verification

Cell balancing manages voltage differences between series-connected cell groups according to the BMS design.

Depending on the BMS configuration, testing may include:

• Balancing activation threshold

• Balancing current

• Balancing status

• Cell voltage measurement

• Balancing termination conditions

Temperature Protection

BMS temperature protection testing evaluates responses to defined temperature conditions.

Functions may include:

• Charging over-temperature protection

• Discharging over-temperature protection

• Low-temperature charging protection

• Temperature sensor fault detection

• Temperature-based current limitation, where supported

The actual functions depend on the BMS hardware, firmware, and approved specifications.

4. CAN, UART and RS485 Communication Testing

Custom battery packs used in industrial equipment and robotics may require communication with external controllers.

Common communication interfaces include CAN, UART, and RS485.

Communication validation may cover:

• Battery voltage reporting

• Current reporting

• State of Charge (SOC)

• State of Health (SOH), where implemented

• Temperature reporting

• Fault information

• Communication timing

• Data format verification

• Communication interruption handling

CAN Communication Testing

For AGV and AMR applications, the BMS may transmit battery information to the equipment controller through CAN communication.

The communication protocol should be defined before integration testing.

Required information may include CAN identifiers, bit rate, message structure, and data scaling.

CAN communication does not automatically provide control over battery charging or discharging. These functions depend on the BMS hardware, firmware, and agreed system design.

Equipment Integration Testing

Battery packs may require integration testing with the customer's equipment.

Testing may include:

• Equipment startup

• Communication compatibility

• Charging operation

• Discharge operation

• Battery status monitoring

• Fault information reporting

The test procedure should follow the approved communication protocol and equipment requirements.

5. Thermal Validation for Lithium Battery Packs

Thermal validation evaluates battery temperature behavior under specified operating conditions.

Lithium battery cells generate heat during charging and discharging due to electrochemical processes and internal resistance.

Electrical connections, busbars, wiring, connectors, and BMS power components also generate heat during operation.

Thermal testing evaluates battery temperature against the approved operating limits.

Temperature Rise Testing

Temperature rise testing measures temperature changes during defined charging or discharging conditions.

Monitoring locations may include:

• Selected battery cells

• Cell connection points

• Busbars

• BMS power components

• Charging and discharging connectors

• Battery enclosure surfaces

Thermocouples or suitable temperature sensors may be used according to the test plan.

High-Temperature Operation Testing

High-temperature testing evaluates battery operation under specified ambient temperature conditions.

Testing may cover:

• Charging behavior

• Discharge performance

• Cell temperature

• BMS temperature

• Temperature protection functions

The test temperature and duration depend on the selected cell specifications and project requirements.

Low-Temperature Operation Testing

Low-temperature testing evaluates battery behavior in cold environments.

Evaluation items may include:

• Discharge capacity

• Voltage behavior

• Discharge current capability

• Low-temperature charging protection

• BMS temperature monitoring

Charging and discharging temperature limits must follow the selected cell manufacturer's specifications.

Thermal Distribution Evaluation

Temperature distribution testing evaluates differences between monitoring points inside the battery pack.

The results can identify areas of heat accumulation near cells, electrical connections, or electronic components.

For battery packs installed inside enclosed equipment, thermal evaluation should consider the installation environment and surrounding heat sources.

6. Mechanical Testing for Custom Battery Packs

Mechanical validation evaluates the battery pack's physical structure and installation compatibility.

The test scope depends on the application and mechanical requirements.

Dimensional Inspection

Dimensional inspection verifies whether the battery pack meets the approved mechanical drawings.

Inspection items may include:

• Length

• Width

• Height

• Mounting hole positions

• Connector locations

• Cable outlet positions

• Installation clearance

For custom robot batteries, dimensional compatibility should be evaluated according to the equipment's installation compartment.

Vibration Testing

Battery packs used in vehicles and industrial equipment may experience vibration during operation.

Vibration testing evaluates the battery pack under defined vibration conditions.

Inspection items may include:

• Enclosure integrity

• Cell fixing structure

• Electrical connections

• Connector retention

• Mounting hardware

• Electrical operation after testing

The vibration profile and test duration depend on the applicable requirements.

Mechanical Shock Testing

Mechanical shock testing evaluates the battery pack's response to specified mechanical impacts.

Test conditions should be established according to the battery application and relevant testing requirements.

Enclosure Integrity

Enclosure inspection evaluates mechanical assembly and structural condition.

Inspection items may include:

• Housing assembly

• Screw connections

• Mounting brackets

• Sealing components

• Cable glands

• Connector installation

• Surface condition

Installation and Removal Testing

For removable battery packs, mechanical validation may include:

• Battery insertion

• Connector alignment

• Locking mechanism operation

• Battery removal

• Mounting structure inspection

• Cable accessibility

The evaluation should reflect the intended installation and maintenance procedures.

7. Environmental Protection Testing

Some custom lithium battery packs operate in environments involving dust, moisture, rain, or water spray.

Environmental testing may be required according to the equipment's installation conditions.

IP Rating Testing

Ingress Protection (IP) ratings are defined under IEC 60529.

Examples include:

The required IP rating depends on the application and environmental exposure.

The IP rating of an individual connector or enclosure component does not establish the rating of the complete battery pack.

Testing should consider the final assembled configuration, including housing joints, connectors, cable outlets, and sealing structures.

Humidity and Condensation

For applications involving humidity or temperature changes, the design may require evaluation of moisture exposure and condensation.

These conditions can affect electrical insulation, metal connections, and electronic components.

Test conditions should be determined according to the project requirements.

8. Applicable Standards and Certification Requirements

Battery pack validation may involve specific safety standards depending on the application and destination market.

Examples include:

The applicable requirements depend on product classification, destination market, battery application, and certification scope.

Design Validation and Certification Testing

Engineering design validation and formal certification testing serve different purposes.

Design validation evaluates the battery against project-specific technical requirements.

Certification testing evaluates the product against applicable standards within the relevant assessment process.

Internal engineering test results do not constitute product certification.

Certification status should be supported by valid documentation covering the relevant battery configuration.

9. Battery Pack Prototype Validation Process

A custom battery pack validation process may include the following stages.

The actual sequence depends on the project requirements.

If a design modification affects electrical performance, thermal behavior, or mechanical structure, the relevant validation activities should be reviewed.

10. Information Required for Battery Pack Validation

Before developing a custom lithium battery pack, OEM customers should provide the following information.

1. Battery Electrical Specifications

Nominal voltage, capacity, charging voltage, continuous discharge current, and peak discharge current.

2. Battery Chemistry

Ternary lithium-ion, LiFePO4, or another specified chemistry.

3. Mechanical Requirements

Battery dimensions, enclosure structure, mounting positions, and installation drawings.

4. Operating Conditions

Ambient temperature, operating duty cycle, vibration exposure, and environmental requirements.

5. BMS Requirements

Protection thresholds, temperature monitoring, balancing, and communication interfaces.

6. Connector Requirements

Charging, discharging, and communication connectors.

7. Testing Requirements

Required electrical, thermal, mechanical, and environmental test conditions.

8. Certification Requirements

Applicable standards and target markets.

9. Project Schedule

Prototype quantity, customer evaluation plan, and production requirements.

These details are used to establish the validation scope and technical acceptance criteria.

11. Custom Battery Pack Development at First Power

provides OEM and ODM custom lithium battery pack development and manufacturing services.

Our business covers electric mobility, robotics, industrial equipment, and energy storage applications.

Our customization scope includes:

• Ternary lithium-ion and LiFePO4 battery pack configurations

• Customized voltage and capacity

• Battery cell selection

• BMS customization according to project requirements

• CAN, UART, and RS485 communication options

• NTC temperature monitoring

• Customized plastic and aluminum enclosures

• Battery connector and wiring customization

• Battery pack assembly

• Technical documentation and project testing coordination

For custom battery pack projects, electrical specifications, thermal requirements, mechanical dimensions, and communication functions are considered during development.

The validation scope is determined according to the confirmed battery configuration, customer specifications, and applicable requirements.

Testing arrangements and required documentation are confirmed according to the project.

Conclusion

Battery pack design validation involves electrical testing, thermal evaluation, mechanical verification, and BMS functional testing.

Each validation activity addresses specific aspects of battery operation and design requirements.

For OEM and ODM projects, defining the validation scope during development helps establish acceptance criteria, testing procedures, and prototype approval requirements.

Whether the application involves an electric bicycle, AGV, AMR, service robot, or industrial battery system, validation should be based on the battery's electrical, mechanical, and environmental specifications.

Developing a custom lithium battery pack for your equipment?

Contact Dongguan Yizhan Electronics Technology Co., Ltd. (First Power) with your battery voltage, capacity, discharge current, mechanical drawings, BMS requirements, and testing specifications.

Our team can review your project requirements and discuss battery pack design, prototype development, and validation arrangements.