Shenzhen Shangguo Technology Co., Ltd. is a leading high-tech enterprise specializing in the research, development, and manufacturing of high-quality replacement batteries for laptops,cameras, medical, industrial, specialty equipment, robot, outdoor energy, and other electronic devices!
Introduction
A lithium battery pack is more than a group of battery cells connected together.
For many devices, the Battery Management System (BMS) plays an important role in protecting the battery, monitoring operating conditions, managing cell performance, and communicating battery status with the host device.
For custom battery packs, the BMS needs to match the battery chemistry, voltage, current, cell configuration, operating environment, and communication requirements of the application.
A properly designed BMS helps create a battery solution that is safer, more reliable, and better integrated with the equipment it powers.
1. What Is a Battery Management System (BMS)?
A Battery Management System, or BMS, is an electronic system designed to monitor and manage the operating condition of a battery pack.
In a lithium battery pack, the BMS can monitor parameters such as:
Depending on the battery design and application, the BMS may also provide cell balancing, battery status reporting, fault detection, communication interfaces, and other customized functions.The BMS works between the battery cells and the device, charger, controller, or other host system.
A simple way to understand it is: Battery Cells → BMS → Device / Charger / Controller
The cells provide the energy, while the BMS helps the battery operate within its defined electrical and temperature limits.
2. What Does a BMS Do?
The functions of a BMS depend on the battery chemistry, pack configuration, and application requirements.
For a custom lithium battery pack, the main functions usually include battery protection, monitoring, balancing, and communication.
Battery Protection
A BMS can monitor battery conditions and trigger protection when defined voltage, current, or temperature limits are reached.
Typical protection functions include:
Cell voltage monitoring is particularly important because excessive overcharge or over-discharge can affect battery life and safety.
However, BMS protection is only one part of battery safety. Proper cell selection, mechanical design, electrical design, manufacturing quality, and testing are also essential.
3. Cell Monitoring & Balancing
In a battery pack containing multiple cells connected in series, individual cell groups may gradually develop differences in voltage and state of charge.
The BMS can monitor individual cell voltages and, depending on the BMS design, perform cell balancing to help maintain a more consistent battery pack condition.
Cell balancing can be implemented using different approaches, including passive or active balancing.
The appropriate balancing strategy depends on factors such as:
For a custom battery pack, balancing should be considered together with the cell configuration and overall battery architecture rather than selected as an isolated function.
4. Battery Monitoring: SOC and SOH
For applications that need more information than basic protection, the BMS may provide battery condition information such as State of Charge (SOC) and State of Health (SOH).
SOC — State of Charge
SOC represents the estimated remaining charge or usable energy of the battery.
For example:
SOC: 80%
indicates that the battery still has a significant amount of usable energy available under the defined operating conditions.
SOH — State of Health
SOH describes the battery's condition relative to its original or reference performance.
Depending on the BMS design, battery monitoring data can be provided to a display, controller, software interface, or other host system.
This can be particularly useful for industrial equipment, robotics, energy systems, medical equipment, and other professional devices where battery status needs to be monitored.
(配图待做)
5. Why Does a Custom Battery Pack Need a Custom BMS?
Not every battery pack needs a completely custom BMS.
For simple applications, an existing BMS platform may be sufficient.
However, a customized or configurable BMS can become important when the battery needs to meet specific electrical, mechanical, communication, or application requirements.
For example, a custom battery project may require:
The BMS should therefore be designed around the battery pack and the equipment rather than treated as a completely
6. CANBUS, RS485 and Battery Communication
For many professional devices, a battery is required to do more than provide electrical power.
The battery may also need to communicate with:
Common communication options include CAN, RS485, UART, SMBus, Bluetooth, and other interfaces depending on the application.
CANBUS
CANBUS is widely used in applications where multiple electronic systems need reliable communication.
It can be used to transmit battery information such as:
CAN communication is commonly found in industrial equipment, robotics, vehicles, energy systems, and other integrated applications.
RS485
RS485 is commonly used in industrial communication environments and can support communication over relatively long cable runs.
When using RS485, the battery and host device need to match the required communication protocol and data format.
For example, an RS485 battery may need to support a specific Modbus register map defined by the host system.
The physical interface alone does not guarantee compatibility.
The communication protocol, baud rate, message structure, register definitions, and data format may all need to match the host device.
7. Communication Compatibility Is More Than a Connector
One common mistake in battery integration is assuming that two devices are compatible simply because they use the same connector or communication interface.
For example, two RS485 battery systems may use different register definitions.
Similarly, two CAN-based battery systems may use different message IDs, data formats, baud rates, or communication schedules.
Therefore, a custom battery project should confirm the communication requirements before the BMS firmware is finalized.
Important information may include:
This information allows the battery engineering team to develop the BMS communication according to the actual host-device requirements.
8. How We Design a Custom BMS for Your Battery Pack
A reliable custom BMS starts with understanding the application.
Our engineering process typically begins by evaluating the customer's device and battery requirements.
Step 1 — Understand the Device
We review:
Step 2 — Define the Battery Configuration
We determine:
Step 3 — Define BMS Functions
Depending on the application, we determine:
Step 4 — Define the Interface
We confirm:
Step 5 — Engineering Validation
The battery pack and BMS are then evaluated through electrical and functional testing before production.
This approach helps ensure that the BMS is not only compatible with the battery cells, but also properly integrated with the customer's equipment.
9. BMS Testing Before Production
BMS design should be validated together with the battery pack before mass production.
Depending on the application, testing may include:
Testing requirements should be defined according to the battery chemistry, pack design, application, and applicable standards.
A BMS test is not simply a test of the PCB itself. The BMS, cells, wiring, connector, charger, and host device should be considered as part of the complete battery system.
10. When Should You Consider a Custom BMS?
A custom BMS may be worth considering when a standard BMS cannot fully meet the requirements of your application.
You may need a custom BMS when:
Your device requires a specific communication protocol
For example:CANBUS / RS485 / UART
Your battery has a special voltage or cell configuration
The BMS needs to match the actual series/parallel architecture and cell chemistry.
Your device requires specific protection parameters
Different equipment may have different requirements for charge, discharge, temperature, and current protection.
Your battery has limited installation space
The BMS PCB may need to fit within a specific battery housing.
Your device needs battery data
For example:SOC / SOH / Voltage / Current / Temperature / Fault Status
Your battery needs mechanical or connector customization
The PCB, wiring harness, connector, and housing may all need to be designed around the equipment.
11. What Information Should You Provide for a Custom BMS Project?
If you are planning a custom lithium battery pack, providing the following information can help the engineering team evaluate the project more efficiently.
Device Information
Battery Requirements
BMS Requirements
Interface Information
If you already have a battery specification, electrical drawing, connector definition, or communication protocol document, providing these materials can help accelerate the engineering evaluation.
12. Custom BMS for Different Applications
The BMS requirements can vary significantly depending on the equipment.
Medical Devices
Medical equipment may require compact battery dimensions, reliable protection, accurate monitoring, and specific communication or charging requirements.
Industrial Equipment
Industrial applications may require higher current capability, robust communication, wider operating temperature ranges, and long-term reliability.
Robotics and AGV/AMR
Robotics applications may require high discharge capability, CANBUS communication, SOC monitoring, and integration with motor controllers.
Surveying Equipment
Professional surveying equipment may require compact battery designs, stable output, accurate capacity, and customized connectors.
Energy Storage
Energy storage systems may require higher-capacity battery configurations, CAN or RS485 communication, monitoring functions, and multiple protection strategies.
The BMS should therefore be selected according to the actual application rather than simply choosing a BMS based on voltage and capacity.
13. Why BMS Design Should Be Part of Battery Pack Development
A battery pack is a complete system.
The cells, BMS, connector, wiring, housing, charger, and host device all need to work together.
For this reason, BMS selection should not be treated as the final step after the battery cells have already been selected.
Instead, BMS requirements should be considered during the early stages of battery pack development.
This allows the engineering team to evaluate:
Cell Chemistry
↓
Pack Configuration
↓
BMS
↓
Communication
↓
Mechanical Design
↓
Testing
↓
Production
A system-level approach can help reduce compatibility problems and unnecessary redesign during the later stages of a project.
14. Need a Custom BMS for Your Battery Pack?
Choosing a BMS is an important part of developing a custom lithium battery pack.
Whether your project requires basic protection, cell balancing, battery monitoring, CANBUS, RS485, or other communication functions, the BMS should be evaluated together with the battery cells and the target device.
At Shangguo Technology, our engineering team works with customers to develop customized battery solutions based on application requirements, including battery configuration, BMS functions, communication interfaces, connectors, and mechanical structure.
If you are developing a new battery-powered device or looking for a replacement battery with specific BMS requirements, share your device specifications with our engineering team.
Tell Us About Your Battery Project
Voltage · Capacity · Current · Runtime · Connector · Communication · Dimensions
Scan to Wechat :
Scan to Whatsapp :
Home
Products
contact
