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BMS1802

18S BMS Slave

The BMS1802 is a fully digital daisy-chain slave engineered for 5S to 18S lithium battery packs in energy storage and mobility systems. It measures every cell to 0.1 mV resolution and balances passively at up to 1000 mA, dissipating as much as 8 W per cell to align large packs quickly. Two RJ45 ports carry 1.5 kV isolated daisy-chain communication over standard CAT-5 cable, and the module is self-powered from the cells it monitors, so it integrates as a plug-and-play slave with no hardware or software configuration.

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3D render of the BMS1802 18S slave board with two RJ45 ports, a dense array of balancing resistors and a cell connector
Line drawing of the BMS1802 from above, showing the balancing resistors, two RJ45 ports and the cell connector
Line drawing of the BMS1802 underside showing the RJ45 ports, connectors and mounting holes

Overview

The BMS1802 is a high-current slave module built for distributed 5S to 18S battery systems. It measures every cell with 0.1 mV resolution and balances passively at up to 1000 mA per cell, clearing imbalance fast across large packs. Two RJ45 ports carry 1.5 kV isolated daisy-chain communication over standard CAT-5 cable, so modules stack reliably under a master. Self-powered from the cells it monitors and waking on master communication, it works out of the box with no configuration.

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The BMS1802 is a fully digital slave BMS for 5S to 18S lithium packs, measuring every cell to 0.1 mV resolution with ±1.6 mV typical accuracy. It tracks temperature through up to five external NTC probes and three onboard sensors, and enforces core cell protection covering over voltage, under voltage, over and under temperature, delta voltage, and balancing faults. The module is self-powered from the cells it monitors, drawing around 300 mW in run state and dropping to roughly 0.05 mW in power down until master communication wakes it. Built for distributed packs, the BMS1802 balances passively at up to 1000 mA per cell with as much as 8 W of dissipation, clearing imbalance far faster than lower-current slaves. It connects through two RJ45 ports with 1.5 kV isolated daisy-chain communication over standard CAT-5 patch cable, stacking with other modules under a master without any hardware or software configuration. Onboard RUN and STAT indicators together with per-cell balancing LEDs make pack status easy to read at a glance.

Highlighted Features

  1. 01

    Flexible Cell Support

    Monitors and protects from 5 to 18 cells, depending on cell chemistry.

  2. 02

    Flexible Temperature Support

    Up to 5 temperature sensors for comprehensive monitoring.

  3. 03

    Automatic Sleep or Run Mode

    Device runs in full power mode when powered up while communicating with master. If master stops communication, slave devices goes to deep sleep mode for minumum power consumption after 3 seconds. Any communication from master will wake the device up immediately.

  4. 04

    Power Supply

    Board is self-powered from the cells it monitors.

  5. 05

    Up to 1A Balancing Current per Cell

    Capable of 1A per cell balancing current. Proper cooling need to be considered at system level.

  6. 06

    Easy Daisy-Chain Integration

    Easy to use, plug-and-play integration with standard CAT-5 cable via RJ45 ports.

Planning a project with the BMS1802?

Send us your cell count, chemistry and current range. Our engineers will reply with a configuration and a quote.

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