1. BMS1820 Introduction
LiBat™ BMS1820 is an advanced battery management system master designed for distributed master-slave battery applications in demanding industrial environments. This fully digital device is a ready-to-use solution for 5S-18S master battery management systems, driving BMS1802 and BMS1202 slave modules over galvanically isolated CAN Bus, RS485 and I/O. Powered from 12V or directly from the battery, it adapts to high voltage, high power and high energy applications through external electrical components such as contactors and current sensors. With four automotive-grade high-side switches and a relay output, the BMS1820 delivers flexible control and, once configured with the correct system parameters, operates seamlessly without the need for ongoing user interaction.
Key Features:
- Built in 5S - 18S cell measurement with 0.1mV resolution
- Up to 420mA adjustable passive balancing current
- Wide input supply range (12V - 80V), 12V or battery powered
- Isolated 1 x CANBus 2.0b, 1 x RS232, 1 x RS485 communication
- Cloud connection and OTA firmware updates
- Advanced I/O: 3 logic inputs, 2 logic outputs, 4 automotive high-side switches, 1 relay output
- Dual channel external current measurement
- Up to 5 external NTC temperature probes
- Standalone, Master and Multi-Master operating modes
- Up to 16 slave modules (BMS1802 / BMS1202) via isolated daisy-chain
- Expandable up to 288 cells total with slave module connection
- Deep sleep and low power consumption modes
Table.1.1: BMS1820 Technical Specifications
| PARAMETER | SPECIFICATIONS |
|---|---|
| Power Source | Self or External Power. (12 - 80 Vdc) |
| Wake Up Trigger | User Button |
| LEDs | Power, Run/Error Status |
| Relays | 1x Relay Output |
| Inputs | 3x Logic Inputs |
| Outputs | 2x Logic Outputs, 4x Automotive High-Side Switches |
| Precharge | Configurable Software Timer |
| DFU Mode | Embedded bootloader for firmware upgrades. |
| Digital Interface-1 | 1x Half Duplex RS485 |
| Digital Interface-2 | 1x RS232 |
| Digital Interface-3 | 1x CANBus 2.0b |
| Communication Protocols | LiBat COM, JSON |
| Communication Protocol | Modbus RTU |
| Current Sensor | Compatible with 5V external current sensors (dual channel) |
| Operating Modes | Standalone, Master, Multi-Master |
| Slave Connections | Up to 16 slaves (BMS1802 / BMS1202) via isolated daisy-chain |
| Number of cells | Up to 18 Cells (5S - 18S) |
| Cell Type | Any battery cell in voltage range |
| Minimum cell voltage | 250 mV |
| Maximum cell voltage | 4500 mV |
| Accuracy of Cell Voltage Measurement | ±1.6mV typical, < ±8.3mV max. |
| Balance Method | Passive Balancing |
| Balance Current | 420mA @ 4.2Vdc cell voltage |
| Temperature Sensor Type | NTC, 10KΩ @ 25 °C |
| Temperature Sensor Accuracy | ±1.5 °C (depends on sensor sensitivity) |
| Number of Temperature Sensor | Up to 5 external sensor probes |
| Operating Temperature | -20 °C to +70 °C (-4° F to +158° F) |
| Relative Humidity | 5% to 95% (non-condensing) |
| Expandability | Up to 288 cells total with slave modules |