How to set up master-slave communication for batteries

October 8,2025

In multi-battery systems, especially those connected in parallel, master-slave communication can achieve coordinated operation and unified control between batteries. The master battery is responsible for communicating with the inverter, EMS, or host computer, while the slave batteries synchronize their operating status, thereby improving system stability and safety.

I. What is the function of master-slave communication?

The core purpose of master-slave communication is to designate one battery in a multi-battery system as the "master control unit" to perform external communication control (for example, connecting to inverters and monitoring equipment), while other batteries act as "slave units" to synchronize internal operating parameters (such as SOC, current, and voltage) to avoid data conflicts or abnormal alarms.

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Battery Communication Cable
ECO - WORTHY RS232/RS485 to USB Adapt Cable for Server Rack Battery & PC Communication (6.6 feet) - battery accessories
ECO - WORTHY RS232/RS485 to USB Adapt Cable for Server Rack Battery & PC Communication (6.6 feet) - battery accessories
ECO - WORTHY RS232/RS485 to USB Adapt Cable for Server Rack Battery & PC Communication (6.6 feet) - battery accessories
ECO - WORTHY RS232/RS485 to USB Adapt Cable for Server Rack Battery & PC Communication (6.6 feet) - battery accessories

ECO-WORTHY RS232/RS485 to USB Adapt Cable for Server Rack Battery & PC Communication (6.6 feet)

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Battery Communication Cable

Common application scenarios

Multiple batteries are connected in parallel
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When connected to a closed-loop communication inverter (such as Growatt, Deye, etc.)
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An EMS system that requires unified reporting to the SOC.
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Main Article

Decoding the Multi-Dimensional Communication Capabilities of the ECO-WORTHY 48V100Ah Server Rack Battery

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Core Topic

The core theme of this article series is “Intelligent Battery Communication,” focusing on the communication functions and technologies of the 48V 100AH server rack battery and its related devices. It covers master-slave communication, upper computer communication, mobile APP communication, and inverter communication, aiming to help users understand and apply these technologies.

II. How to set up master-slave communication

1.

Currently, the batteries that support master-slave communication include 48V 100Ah Server Rack series batteries.

Use the RS485 communication cable provided with the battery to connect the RS485-2 interface between the batteries.

RS232 to USB 

RS485 to USB

The RS232 to USB cable is primarily used to connect devices with an RS232 interface to those with a USB interface . It can convert signal levels and communication protocols, allowing these two different types of interfaces to be compatible.

 

The RS485 to USB communication cable is a device for interface conversion. It can convert data from the RS485 protocol to the USB protocol, and vice versa. In this way, a computer can communicate with devices that support the RS485 protocol, such as the 48V(51.2V) 100AH Lithium Iron Phosphate (LiFePO4) server rack battery, via the USB interface. This allows for operations like connecting to a host computer or SolarAssistant, reading battery data, and updating battery firmware.

2.

Set the address via the DIP switch

The master battery address is set to 1

The slave battery addresses are set to 2–32 in sequence

3.

If communication with the AIO is required, select the correct protocol in Mobile App, Host PC software and External display ESM-100 .

After correct setting and connection, you can view the data of each battery in the APP, host computer, and external display ESM-100

III. Troubleshooting & Solutions

Q: The slave unit is not recognized / battery details cannot be viewed

A: Address conflict or improper wiring. Please verify the DIP-switch address of each battery and confirm that the RS485 cables are connected in the correct daisy-chain order.

Q: Data between batteries is out of sync

A: Cell imbalance or cable interference. Please inspect the RS485 cables for damage and ensure all batteries have undergone simultaneous charge/discharge cycles.

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Master-slave communication is a key component in building a highly stable battery system. Setting up a master-slave system not only allows batteries to operate in tandem but also lays the foundation for subsequent closed-loop control, host computers , and app connectivity .

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