High-Voltage RELAY Schemes
Digital Board + External Relay BMS for Industrial ESS
High-voltage relay BMS architecture: digital control board paired with discrete high-current external contactors for industrial ESS, telecom, and large-scale storage. Unlimited current scaling, 2 A active balancing, and CAN/RS485/Bluetooth for 8S-24S LiFePO4.
Snapshot
Lead Time
2–3 weeks
MOQ
50 units
OEM/ODM
Supported
Delivery
3— Days DDP
Warehouse
Poland Local
Configuration
8S-24S
Overview
Industrial-Grade External Relay BMS
SSLBATT Relay Series is an external relay BMS engineered for high-power industrial applications where standard integrated BMS current limits are insufficient. By driving external contactors through a dedicated relay interface, the architecture decouples BMS control logic from the power path – enabling unlimited current scaling for industrial ESS, telecom rectifier banks, and large-scale storage deployments.
The Relay Series supports 8S to 24S LiFePO4 configurations with 2 A active balancing, CAN and RS485 communication for EMS integration, and Bluetooth for local monitoring. Each unit is factory-configured and tested before shipment.
Situation
Your industrial energy storage system requires a BMS architecture that can scale to hundreds or thousands of amps – far beyond the limits of integrated board BMS units. You need a BMS that separates control logic from the power path, using external contactors sized for your specific current demand, while providing 2 A active balancing, CAN/RS485 communication for EMS integration, and Bluetooth for local monitoring.
The Challenge
Standard integrated BMS units have a fixed current rating determined by onboard MOSFETs – scaling beyond 500-600 A requires replacing the entire BMS board, even if the control logic is adequate. This couples the protection electronics to the power path, forcing costly upgrades when current demands increase and creating a single point of failure where a BMS board fault takes down the entire system. Without external relay architecture, industrial ESS deployments are limited by the BMS current rating rather than the contactor specification.
How do you select an industrial BMS with external relay architecture for unlimited current scaling, active balancing, and EMS communication in large-scale energy storage systems?
Our Answer
SSLBATT Relay Series uses a digital control board with a dedicated dry-contact relay driver that interfaces with external high-current contactors – decoupling BMS protection logic from the power path for unlimited current scaling. With 2 A active balancing, CAN 2.0B and RS485 (Modbus RTU) communication, Bluetooth monitoring, and support for 8S-24S LiFePO4 configurations, it provides an industrial-grade BMS solution for ESS deployments where standard integrated BMS current limits are insufficient – with factory configuration and testing before shipment.
External Relay Architecture
The dry-contact relay driver controls any externally sized contactor, enabling current scaling from 100 A to 10,000 A+ by selecting appropriate contactors. The control board remains the same – only the contactors change as system power requirements grow, simplifying spares management and BOM standardization.
EMS Integration Readiness
CAN 2.0B and RS485 (Modbus RTU) provide telemetry data – SOC, voltage, current, temperature, cell voltages, and fault status – for integration with building management systems, SCADA, and energy management platforms. Protocol mapping is configurable for your specific EMS requirements.
Factory-Configured Deployment
Each Relay Series unit is factory-configured to your system specifications – string count, protection thresholds, communication protocol, and relay logic. Contactors are sourced and integrated to your current requirements, and the complete assembly is tested before shipment.
Where It Fits Best
| Application | Why it fits |
|---|---|
| Industrial ESS with high current demand | External relay architecture scales to any current rating via external contactors. |
| Telecom rectifier and backup systems | 48 V telecom-compatible with reliable dry-contact switching and remote monitoring. |
| Large-scale storage and microgrids | CAN/RS485 integration with EMS for centralized control and data logging. |
| High-voltage commercial battery banks | 8S-24S support covers 24 V to 76.8 V nominal configurations. |
Engineering Guidance for Industrial ESS
Relay and contactor selection
| Design item | Why it matters |
|---|---|
| Contactor coil voltage and current rating | Must match the relay driver output and system current requirements. |
| Arc suppression and snubber circuits | Reduces contact wear and extends contactor life in high-current switching. |
| Pre-charge circuit integration | Prevents inrush current damage when connecting to inverter DC bus. |
BMS logic alignment
Proper BMS configuration ensures reliable operation across all operating states:
| BMS item | Engineering purpose |
|---|---|
| Overcurrent protection thresholds and delay | Coordinates with external contactor trip curve to avoid nuisance trips. |
| Temperature derating and thermal management | Protects BMS electronics under sustained high-power operation. |
| Low-temperature charge protection | Prevents LiFePO4 damage during cold charging. |
| Active balancing parameters and timing | Maintains cell-level SOC consistency across large series strings. |
Engineering Data
Specification Snapshot
Procurement-friendly parameters for fast vendor qualification. Request the PDF datasheet for electrical curves and compliance documents.
SKU
BMS-RELAY-SERIES
Voltage Range
8S-24S LiFePO4
Current Scaling
External Relay - Unlimited
Active Balance
2 A Active Balancing
Communication
CAN / RS485 / Bluetooth
Operating Temp
-20 °C to 65 °C
Safety Layer
BMS & Safety
Engineer-grade protection logic designed to prevent the failures that trigger warranty claims, logistics delays, and downtime in high-power industrial deployments.
Overcharge Protection
Voltage ceiling enforcement and active balancing coordination.
Over-discharge Cutoff
Pack health protection under deep discharge at high loads.
Short Circuit Protection
Fast relay driver response for external contactor trip.
Temperature Protection
NTC monitoring with configurable derating thresholds.
Overcurrent Protection
Configurable thresholds with delay coordination for contactor.
Low-Temp Charge Lockout
Prevents LiFePO4 damage during cold temperature charging.
Cell Imbalance Detection
Active 2 A balancing with configurable trigger voltage.
Dry-Contact Relay Driver
Galvanically isolated control for external contactor switching.
Integration
Inverter Compatibility
We support common inverter/EMS brands through factory-tested protocol mapping (CAN/RS485) and BMS parameter tuning for external relay architectures. Share your inverter model and target charge profile to validate a clean integration. Custom BMS protocol available on request.
Where It Wins
Applications
Match this SKU to proven deployment contexts.
Industrial & C&I Energy Storage
External contactor scaling for ESS packs beyond integrated MOSFET limits.
Large-Scale ESS & Grid Storage
EMS-ready CAN 2.0B / Modbus RTU telemetry for multi-MWh deployments.
High-Current Backup Power
Dry-contact relay driver for uninterruptible high-amp load paths.
OEM Battery Pack Programs
Factory-configured protection thresholds and string counts per program.
FAQ
Frequently Asked Questions
What information is required before requesting an OEM quote for the Relay Series BMS?
Share system voltage (8S-24S), peak and continuous current requirements, external contactor specifications, inverter or EMS model, and operating temperature range. These inputs allow engineering fit checks before order confirmation.
Does SSLBATT support custom BMS protocol mapping for specific inverters?
Yes. SSLBATT supports protocol alignment for CAN and RS485 communication with major inverter brands including Victron, Deye, Growatt, GoodWe, SMA, Solis, Huawei, and Schneider. Custom protocol mapping is available for OEM and ODM projects.
How does external relay scaling work for high-current applications?
The Relay Series uses a dry-contact relay driver that interfaces with external contactors, enabling unlimited current scaling. This architecture separates the BMS logic from the power path, making it suitable for high-power industrial ESS, telecom rectifiers, and large-scale storage systems.
How are lead time and MOQ handled for B2B programs?
Lead time and MOQ are confirmed after technical fit review and configuration lock. Standard lead time is 3-4 weeks with MOQ starting at 50 units. Poland Local Warehouse support available for qualified partners.
Request Quote
Request OEM Quote
Factory-direct pricing, MOQ details, and OEM/ODM timelines for the Relay Series External Relay BMS.