Requirement specification template Passive Balancer 4S-8S
TemplatesThis template provides a structured framework for the specification and development of a passive load balancer. It focuses on precise voltage monitoring and thermal management to maximize the lifespan of LiFePO4 or Li-ion battery packs in 12V to 24V systems (4S to 8S).
Important: This template serves as a technical foundation. Since balancing processes generate heat through targeted energy dissipation, thermal limits and shutdown logic must be strictly adapted to your specific PCB layout and enclosure design.
How to use this template
- Adjust Configuration: Decide whether the design will be implemented as a 4S (12V) or 8S variant (24V) and adjust the form factor requirements accordingly.
- Validate Thresholds: Verify the activation voltage (Default: 3.60 V). Depending on the cell chemistry and desired cell preservation, this value can be adjusted within the ETRM environment.
- Thermal Integration: Use the "Thermal Design" requirements to plan the necessary cooling areas (thermal vias) in the PCB layout.
Tag Legend (Disciplines & Categories)
Each requirement is categorized to support coordination between hardware development, manufacturing, and quality assurance:
- Hardware: Specifications for component selection (reference ICs, MOSFETs, shunt resistors).
- Safety: Safety-critical aspects such as reverse polarity protection, quiescent current, and fire protection.
- Thermal: Requirements for heat dissipation and thermal monitoring of the PCB temperature.
- Interface: Definition of physical cell connections (connectors) and visual status feedback (LEDs).
- Compliance: Regulatory requirements regarding environmental compatibility (RoHS) and electromagnetic compatibility (EMC).
Regulatory Framework & Standards
Use this template as a basis for meeting international electronic and safety standards:
- 2014/30/EU (EMC Directive): Ensuring interference-free operation near other electronics.
- IPC-CC-830B: Standard for the use of conformal coating in humid environments.
- IEC 60068-2-6: Vibration resistance testing (crucial for mobile storage/RVs).
Quality Assurance & Safety
Managing this specification within the ETRM system enables seamless documentation of safety factors. Especially when using lithium cells, validating the shutdown voltage and standby consumption is essential to reliably prevent cell damage or thermal instabilities (thermal runaway).
Requirement Preview
| Structure element | Requirement | Description | Tags |
|---|---|---|---|
1 Electrical Parameters | Activation Voltage | Balancing activation at 3.60 V ± 10 mV per cell. | Hardware |
1 Electrical Parameters | Quiescent Current | Standby consumption < 20 µA per cell to prevent deep discharge. | HardwareSafety |
2 Safety Functions | Thermal Monitoring | Bypass current shutdown at PCB temperatures > 85°C. | SafetyThermal |
2 Safety Functions | Reverse Polarity Protection | Protection against incorrect cell connector wiring during assembly. | Safety |
3 Mechanics & Form Factor | Thermal Design | Dissipation of shunt heat via large copper inlays and thermal vias. Max heating of adjacent components < 20K above ambient. | ThermalHardware |
3.1 Enclosure & Dimensions | Dimensions 4S Variant | Maximum dimensions 45mm x 50mm x 15mm (L x W x H). | Hardware |
3.1 Enclosure & Dimensions | Dimensions 8S Variant | Maximum dimensions 80mm x 50mm x 15mm (L x W x H). | Hardware |
4 Interfaces & UX | Status LEDs | Optical indication of active balancing process per channel. | Interface |
5 Environmental Conditions | Operating Temperature | Safe operation within a range of -20°C to +70°C. | Thermal |
5 Environmental Conditions | Moisture Protection | Coating with conformal coating according to IPC-CC-830B. | Safety |
6 Reliability & Standards | MTBF Target | Mean time between failures of at least 80,000 hours at 40°C. | Compliance |
6 Reliability & Standards | EMC Directive | Compliance with Directive 2014/30/EU (Emission/Immunity). | Compliance |
6 Reliability & Standards | REACH & RoHS | Compliance with 2011/65/EU; avoid lead-based solders and SVHCs. | Compliance |
Disclaimer: This template serves as a guide for requirement management. Use is at your own risk. Particularly with battery technology, all designs must be reviewed by qualified electronic engineers and prototypes must be validated under laboratory conditions.