Maker Forem: CM Batteries

Lithium-ion Battery BMS Sensor Guide: Types, Functions, and Practical Applications

CM Batteries — Wed, 04 Feb 2026 18:21:07 +0000

In lithium-ion battery systems, the BMS (Battery Management System) is often understood as a "protection circuit." However, in practical engineering, what truly determines the reliability of the BMS is not the MOS transistor or control chip, but the way it acquires data—that is, the sensor system.

Whether in medical equipment, industrial equipment, robots, or mobile terminals, the BMS must rely on various sensors to perceive the battery status in real time in order to make accurate judgments. This article will systematically explain the common sensor types in lithium-ion battery BMS, their respective functions, and key considerations in engineering design, starting from practical applications.

Why does the BMS rely so heavily on sensors?
The working logic of the BMS can be simply understood in three steps:
Sensing → Judgment → Control

Sensors are responsible for "sensing" voltage, current, and temperature.

The control unit is responsible for "judging" whether there is a risk.

The execution unit is responsible for "controlling" charging and discharging or disconnecting the circuit.

If the sensor data is inaccurate or the response is not timely, the BMS protection mechanism may make misjudgments, which can affect battery life and lifespan at best, and pose safety risks at worst.

Voltage Sensor: The Basic Sensing Unit of the BMS

Among all sensors, voltage detection is the most basic and core function.

What is its main function?
Real-time monitoring of individual cell voltage
Monitoring the total voltage of the battery pack
Supporting overcharge and overdischarge protection
Providing data basis for cell balancing
In most lithium-ion battery systems, the voltage sampling function is integrated inside the BMS sampling IC, monitoring each cell string through a multi-channel ADC.

Key points in engineering:
Accuracy directly affects the reliability of protection thresholds
High-series systems (such as 48V and above) require higher sampling stability
PCB layout and anti-interference design are crucial

Current Sensor: The Key to Connecting Safety and Battery Life
If voltage determines the safety boundary, then the current sensor determines "how the system uses the battery." Core Functions
Monitoring charging and discharging current
Implementing overcurrent and short-circuit protection
Supporting SOC (State of Charge) calculation
Common Implementation Schemes
In actual projects, there are mainly two options:

Shunt Resistor Scheme
Low cost, simple structure, suitable for small and medium current systems

Hall Current Sensor Scheme
Provides isolated measurement capabilities, more suitable for medical, industrial, and high-current applications

Selection Considerations

For equipment with high safety requirements and long-term stable operation, the reliability of current measurement is often more important than cost. This is why high-end BMS systems tend to use Hall effect sensors.

Temperature Sensor: The first line of defense against thermal runaway
Temperature is one of the most sensitive variables in lithium battery safety.
Value of Temperature Monitoring
Preventing performance degradation due to overheating
Limiting charging in low-temperature environments
Protecting BMS power devices (MOSFETs)

Common Practices
Most BMS systems use NTC thermistors, placing multiple temperature measurement points inside the battery pack to monitor:

Cell surface temperature
Internal environment of the battery pack

Key heat-generating component areas

A Common Misconception

Monitoring the temperature of only "one point" often fails to reflect the true thermal state of the entire battery pack, which is especially dangerous in high-rate or densely structured systems.

Other Sensing and Advanced Monitoring Functions

In some high-end or high-safety applications, BMS systems also integrate more sensing and detection mechanisms, such as:

Insulation status monitoring

Housing or grounding status detection

Battery installation or connection status detection

These designs are common in medical equipment, energy storage systems, and industrial applications, used to further reduce system-level risks.

How does sensor data affect the actual performance of the BMS?

The significance of sensors lies not only in "measuring data," but also in how the data is used.

Voltage + Current → Determines charging and discharging strategy

Current + Time → Determines SOC accuracy

Temperature + Historical data → Affects lifespan and safety judgments

With the same hardware sensors, the BMS control logic may be completely different in different applications. This is the fundamental difference between general-purpose and customized BMS systems.

Why is sensor design indispensable for customized lithium battery BMS?

For customized lithium battery projects:

Different cell models

Different series and parallel structures
Different operating environments and regulatory requirements
The number, location, accuracy, and control logic involved in the sensors need to be clearly defined during the design phase, not as an afterthought.
Professional battery solutions often start with "customization" at the sensor level. Conclusion
BMS sensors are the "sensory neural network" of lithium-ion battery systems.
They determine what the BMS can see, what it can judge, and ultimately how it protects the battery and the equipment.
For equipment manufacturers and system integrators, understanding the working logic of BMS sensors helps in making more rational battery solution choices and avoiding many hidden reliability problems.

High and Low Temperature on the Performance of Lithium-ion Batteries

CM Batteries — Sun, 11 Jan 2026 20:37:14 +0000

Lithium-ion batteries, specifically Lithium Iron Phosphate (LiFePO4) and Ternary Lithium (NMC) batteries, are widely used as power sources for new energy vehicles due to their high energy density, broad operating temperature range, long cycle life, and high safety reliability. However, during the charging and discharging process, lithium batteries generate reversible reaction heat, ohmic heat, polarization heat, and side reaction heat. The amount of heat generated is primarily influenced by internal resistance and charging current.

Power batteries are remarkably "delicate." Temperature has a significant impact on their overall performance, primarily across three dimensions: operational performance, lifespan, and safety. In electric vehicle applications, the optimal operating range is generally determined by balancing performance, longevity, and safety based on thermal testing results. It is widely accepted that the ideal operating temperature for batteries is between 20°C and 30°C.

The Impact of Temperature on Capacity and Lifespan
Lithium battery capacity fluctuates with temperature. Testing reveals that for every 1°C increase in temperature, capacity rises by approximately 0.8%. However, elevated temperatures cause cumulative damage; both cycle life and capacity gradually decline. Research indicates that at a standard ambient temperature of 25°C, an increase of 6°C to 10°C can double the float charging current, effectively halving the battery's lifespan.

While capacity increases at higher temperatures (reducing the depth of discharge for the same total discharge), exceeding certain thresholds is hazardous. At 45°C, service life may temporarily seem extended, but charging above 50°C accelerates acid corrosion on the battery plates and speeds up the aging of the battery casing.

Available capacity decays at varying rates depending on the cold:

25°C: 100% available capacity

0°C: 85% available capacity

-10°C: 70% available capacity

When temperatures drop, discharge voltage also decreases significantly, causing the battery to reach its cut-off voltage faster. This results in low-temperature discharge capacity being markedly lower than room-temperature capacity.

Effects of Low Temperature on Performance
At low temperatures, available capacity is reduced and charge/discharge power is restricted. If power is not limited, lithium ions may precipitate internally, leading to irreversible capacity decay and safety hazards. Lower ambient temperatures lead to:

Reduced activity of active materials.

Increased internal resistance and viscosity of the electrolyte.

Slow ion diffusion, making it harder for ions to intercalate (embed) into electrodes.

It is a common experience that lithium batteries last shorter in winter. While discharge capacity loss at low temperatures is often reversible after returning to room temperature, low-temperature charging is much more dangerous. Charging below 0°C can cause lithium ions to plate onto the surface of the graphite anode rather than intercalating into it, forming metallic lithium dendrites. These dendrites consume recyclable lithium ions, permanently reducing capacity, and can pierce the separator, leading to internal short circuits and safety failures.

Effects of High Temperature on Safety
Safety risks increase significantly when temperatures exceed 45°C. Misuse or charger failure at high temperatures can trigger violent internal chemical reactions and rapid heat accumulation. This can lead to leakage, venting, smoke, or in extreme cases, combustion and explosion.

Key chemical reactions at high temperatures include:

SEI Film Decomposition: The protective layer decomposes exothermically between 90°C and 120°C.

Lithium-Electrolyte Reaction: Above 120°C, the anode contacts the electrolyte directly, causing exothermic reactions.

Electrolyte Decomposition: Occurs above 200°C, releasing heat.

Cathode Material Decomposition: In an oxidized state, cathode materials decompose, releasing oxygen which further reacts with the electrolyte.

Binder Reaction: Exothermic reactions between intercalated lithium and fluoride binders.

To ensure reliable performance in extreme environments, CM Batteries utilizes advanced wide temperature battery technology to provide stable power solutions that withstand both freezing winters and scorching summers.

Low-power battery solutions for the smart security field

CM Batteries — Sun, 11 Jan 2026 20:06:24 +0000

In the field of intelligent security, low-power batteries are becoming the core power solution for edge devices such as surveillance cameras and sensors. These batteries provide long-lasting endurance, helping to reduce device maintenance costs while improving the user experience.

However, low power does not equate to low risk. Especially as global e-commerce platforms like Amazon implement increasingly strict battery safety requirements, product compliance has become the primary barrier to market entry. In recent years, frequent safety incidents caused by battery design flaws or the lack of overcharge/overdischarge protection mechanisms have led not only to product recalls but also to severe consequences such as platform delistings and banned listings.

Recently, a power bank brand announced a recall of over 490,000 units because "some battery cell raw materials may pose a combustion risk in extreme scenarios." Another well-known brand recalled over 1.1 million power banks in the United States, stating that "the lithium-ion battery may overheat, leading to plastic parts melting, smoke, and fires." These safety issues are exactly what Amazon focuses on during audits. They also serve as a warning to the security industry—many smart cameras and doorbell products have been forced off the shelves due to battery issues, even triggering brand trust crises.

Today, end consumers and sales channels prioritize product safety far more than battery life. Building a systematic safety architecture that covers cell selection, power management, and full-lifecycle reliability is becoming the core mission for the sustainable development of the intelligent security industry.

Compliance as Competitiveness: The Dual Threshold of Safety and Market In the perception of many security companies, "endurance priority" is the core logic of product design, while safety is often seen as an "add-on." However, the reality is that with tightening global regulations and rising channel barriers, safety has shifted from a "bonus point" to an "entry permit." Compliance capability directly determines whether a company can successfully enter mainstream markets.

Examining the current state of compliance in the security industry reveals two typical problems:

Selective Compliance: To control costs, many companies only perform basic certification for core markets or strictly test only the inspection samples, while relaxing standards and cutting corners during mass production.

Single-Dimensional Compliance: These companies often focus only on the safety of the battery itself, ignoring the energy hazards (such as electric shock or overheating) posed by the entire system, as well as electromagnetic compatibility for wireless communication, environmental protection, and energy efficiency.

This "fragmented" compliance model is no longer sustainable. Global platforms like Amazon are constantly strengthening supervision. Requirements range from clearly labeling battery types (lithium metal, lithium-ion, alkaline) to providing detailed product spec sheets and certifications like UN38.3 for international transport and IEC 62133 safety standards. Any missing requirement can lead to product removal or suspension of sales privileges.

Compliance Model: Upgrading from "Access" to "Trust" In an environment where industry compliance awareness is generally weak, it has taken a forward-looking approach by establishing a global compliance system.

At the battery level, CM Batteries strictly follows international standards. All products pass the global UN38.3 certification to ensure stability during transportation. Furthermore, products meet UL 2054 and IEC 62133-2 consumer battery safety standards to minimize potential risks during use.

Notably, CM Batteries selects battery partners that have completed UL 2054 certification through NRTL laboratories recognized by the US OSHA—a high standard achieved by few in the industry. Unlike routine sample-only testing, NRTL certification covers cell selection, system design, and safety testing, while also auditing the manufacturing process, equipment, and quality systems. More importantly, NRTL involves regular on-site factory inspections to ensure consistent safety performance throughout the battery's lifecycle.

Addx also extends compliance to the entire device. Its products have passed the UL/IEC 62368-1 safety standard for information technology equipment, which focuses on potential energy hazards such as electric shock, fire, overheating, and explosions.

Building a Traceable, Verifiable, and Reliable Safety Paradigm If compliance is the "external threshold," then a full-link quality traceability system is the "internal defense line."

The security industry currently faces two major pain points in battery management: difficult cell traceability (relying on manual offline management) and production loopholes (manual cell sorting and spot welding lead to errors). CM Batteries addresses this by building a comprehensive traceability system:

Cell Management: CM Batteries uses a "batch + individual" dual-track tracking mechanism. Every cell is assigned a unique identity through capacity grading and laser coding, achieving closed-loop data management from raw material to finished product.

Sorting and Assembly: By combining automated equipment with MES (Manufacturing Execution Systems), human error is minimized. Cells are grouped based on precise voltage and internal resistance parameters, and spot welding is verified in real-time by the MES to prevent the use of incorrect materials.

Protection Board (BMS) Testing: As a core safety component, the protection board undergoes over ten tests, including overcharge/overdischarge protection and short-circuit response time.

Conclusion
Battery life determines the length of the user experience, but safety determines the lifespan of the brand. Companies like CM Batteries are driving this standard forward by providing high-quality IoT battery solutions that integrate international standards into the entire product lifecycle. By prioritizing safety and building end-to-end control systems from the cell to the final device, companies can ensure sustainable development and win long-term user trust in the global market.

From Modeling to Management: Artificial Intelligence Empowers Battery Electrochemical Models

CM Batteries — Sun, 11 Jan 2026 19:53:40 +0000

The integration of Artificial Intelligence (AI) with electrochemical models is transforming lithium-ion battery management. Researchers from Xi'an Jiaotong University recently published a comprehensive review in the Journal of Energy Chemistry, detailing how AI enhances the entire lifecycle of battery models—from construction and parameterization to dynamic identification.

The Evolution of Electrochemical Models Electrochemical models, such as the Pseudo-Two-Dimensional (P2D) model, are essential for peering into the "black box" of a battery. They describe internal dynamics like ion migration and interface reactions. However, their complexity (partial differential equations) often makes them too computationally heavy for real-time Battery Management Systems (BMS).

Model Simplification: AI techniques like Physics-Informed Neural Networks (PINNs) and machine learning are used to reconstruct P2D models into faster versions (e.g., SPM or SPMe) without losing physical accuracy.

Mechanism Insight: These models help identify risks like lithium plating, dendrite growth, and thermal runaway.

AI-Driven Parameterization Accurate parameters are the foundation of any model. Traditionally, these are obtained through:

Direct Measurement: Techniques like SEM-FIB, X-ray CT, and EIS.

Numerical Simulation: Methods like Density Functional Theory (DFT) and Molecular Dynamics (MD).

How AI Enhances This: Deep learning algorithms can automatically extract microstructural features from SEM images, while machine learning force fields accelerate multi-scale simulations, combining the precision of first-principles with high efficiency.

Dynamic Parameter Identification Battery parameters are not static; they shift with state-of-charge (SOC), temperature, and aging.

Model-Based Methods: Utilizing Extended Kalman Filters (EKF) and observers for real-time estimation.

Intelligent Methods: Using Genetic Algorithms (GA) and Particle Swarm Optimization (PSO).

The Decoupling Challenge: AI helps solve parameter coupling issues through sensitivity analysis and multi-step optimization strategies, ensuring that sensitive parameters are identified accurately under varying conditions.

Future Perspectives: Digital Twins and LLMs The research highlights three revolutionary frontiers for the next generation of battery technology:

Digital Twins (DT): Creating a real-time mapping between physical batteries and digital models for continuous self-updating.

Deep Reinforcement Learning (DRL): Optimizing fast-charging protocols and thermal management in real-time.

Large Language Models (LLMs): Integrating LLMs with electrochemical models to provide interpretable diagnostics and automated model selection.

Conclusion
The synergy between AI and physical models is paving the way for safer, longer-lasting, and faster-charging energy solutions. By moving from static offline analysis to dynamic online management, AI-augmented models provide the scientific basis for advanced energy storage and electric vehicle platforms.

As a leader in the energy sector, CM Batteries leverages cutting-edge battery technology to design and manufacture a high-quality custom battery pack tailored to complex industrial and commercial needs, ensuring peak performance through optimized electrochemical management.

How to choose the right voltage/capacity for your golf cart: 36V vs 48V vs 72V

CM Batteries — Sun, 11 Jan 2026 19:39:21 +0000

In the world of golf, the electrical configuration of a cart directly impacts its performance and user experience. The two most critical parameters are voltage and capacity. This article explores the common 36V, 48V, and 72V systems and how different capacity configurations influence range, helping you select the ideal CM Batteries lithium battery solution for golf cart.

I. Analysis of Common Voltage Systems(1) 36V SystemsBattery Composition: Traditional lead-acid 36V systems usually consist of six 6V batteries in series. This setup balances power and efficiency for standard golf carts. CM Batteries lithium solutions for 36V (12S LiFePO4) systems utilize advanced lithium-ion technology, offering higher energy density than lead-acid to provide stable power within a compact footprint.Performance: On flat terrain with light loads (1-2 passengers), 36V systems provide steady power at speeds of 10-15 mph. However, performance drops significantly on inclines or with 3-4 passengers. CM Batteries high discharge performance helps mitigate this lag by providing higher bursts of current, though the overall ceiling remains lower than high-voltage systems.Range: A 36V 60Ah CM Batteries pack provides $2.16\text{kWh}$ of energy. Under ideal conditions, it covers 18-25 miles. In real-world scenarios with frequent stops and hills, this may drop to 12-15 miles.

(2) 48V Systems Battery Composition: Usually configured as four 12V or six 8V batteries. In a 48V (16S LiFePO4) system, CM Batteries utilizes an optimized Battery Management System (BMS) to monitor each cell, ensuring safety and peak efficiency.Performance: 48V systems offer approximately 33% more power and torque than 36V systems. This allows carts to maintain speed on 15° slopes and reach top speeds of 15-19 mph.
Range: A 48V 60Ah CM Batteries pack delivers $2.88\text{kWh}$. Because 48V systems operate at a lower current for the same power output (e.g., 25A vs 33A for a 1200W motor), energy loss is minimized. Users can expect a range of 25-35 miles.(3) 72V SystemsBattery Composition: These high-voltage systems are found in high-end or modified performance carts. CM Batteries 72V (23S LiFePO4) solutions are engineered with premium cell materials to ensure reliability in high-voltage environments.Performance: This system delivers extreme power. Carts can exceed 20 mph and tackle steep hills without speed degradation. The high voltage provides massive torque for demanding terrains.
Range: A 72V 80Ah CM Batteries pack offers $5.76\text{kWh}$. On good roads, the range can exceed 50-60 miles. Even under heavy use, the efficiency of the high-voltage/low-current design ensures superior longevity per charge.

II. How Capacity (Ah) Affects RangeBattery capacity, measured in Amp-hours (Ah), dictates the total energy stored. Higher capacity equals longer runtime.

CM Batteries uses lightweight materials to ensure that increasing capacity doesn't unnecessarily bog down the cart's efficiency.III. Selecting the Right Setup for Your Needs1. Terrain RequirementsFlat & Small Courses: A 36V system with a 60Ah-80Ah CM Batteries pack is cost-effective and sufficient for daily flat-ground use.Hilly or Large Courses: 48V or 72V systems are necessary. 48V is the "sweet spot" for most hilly courses, while 72V is best for extreme performance.

Frequency of UseOccasional/Private Use: A 36V system with moderate capacity is ideal. CM Batteries lithium packs have an extremely low self-discharge rate, making them perfect for carts that sit idle for periods.High-Frequency/Commercial Use: 48V or 72V systems with large capacity (100Ah+) are recommended to reduce charging frequency and lower long-term operational costs.
Budget ConsiderationsBudget-Friendly: 36V systems offer the lowest entry price for batteries and controllers.Premium Performance: 72V systems require a higher initial investment but offer the best experience and highest efficiency for commercial ROI.Balanced: 48V systems provide the most popular balance of performance vs. cost.Choosing the right voltage and capacity is vital for your golf cart’s longevity. By choosing CM Batteries, you ensure your cart remains in peak condition, adding convenience and enjoyment to every round of golf.

Case Analysis and Optimization of Solid-State Battery Technology

CM Batteries — Sun, 11 Jan 2026 19:31:29 +0000

In 2026, Solid-state batteries are leading the global lithium battery industry into a new era with their disruptive performance advantages. Below is an in-depth analysis of technical pathways, market landscapes, process innovations, and the strategic positioning of CM Batteries.

Technical Advantages and Development Trends The core of a solid-state battery lies in the solidification of the electrolyte. Compared to traditional liquid lithium batteries, it offers significant advantages in energy density and safety.

Technology Shift: Solid-state batteries replace flammable liquid electrolytes and separators with solid electrolytes (e.g., sulfides, oxides). This eliminates the risk of leakage and thermal runaway while the "separator-free" design further compresses battery volume.

Mainstream Categories: Solid electrolytes are currently categorized into four types: oxides, sulfides, polymers, and halides.

Evolutionary Path: While semi-solid batteries (based on oxides and polymers) currently lead the market, bulk-type sulfide all-solid-state batteries are recognized as the ultimate goal for commercialization due to their superior ionic conductivity and energy density.

Market Demand and Application Expansion The market for solid-state batteries is on the brink of an explosion. The Asia-Pacific region, particularly China, currently accounts for over 50% of the global market share.

Power Batteries (Main Battlefield): In the first half of 2025, domestic semi-solid-state battery installations exceeded 1.2 GWh. As energy densities of 360 Wh/kg and above become more common, the automotive sector will remain the primary growth engine.

Consumer Electronics (Early Adoption): The high energy density perfectly meets the needs of premium smartphones and wearables, with penetration rates expected to be the first to exceed 10%.

Energy Storage (Long-term Potential): Despite cost sensitivity, solid-state battery penetration in the ESS (Energy Storage System) market is projected to reach approximately 2% by 2030 as technology scales and costs decline.

Global Supply Landscape and Capacity Planning China currently dominates global production capacity, with a projected share of over 80% by 2025.

Critical Milestone: 2027 is widely regarded as the "Year One" for mass production of all-solid-state batteries. Giants such as Toyota, Samsung, GAC, Qingtao, and WeLion plan to achieve large-scale delivery by this time.

Capacity Layout: In the first three quarters of 2025, new planned capacity in China reached 36.6 GWh, signaling a significant acceleration in industrialization.

Material and Process Innovation Materials: Sulfide electrolytes are expected to capture over 40% of the market share by 2035. Anode materials are transitioning from silicon-based to lithium metal anodes to achieve higher room-temperature capacity and lower potential.

Manufacturing: Solid-state batteries have restructured the production process, introducing new equipment such as fibrillation and isostatic pressing machines. This transformation creates massive growth opportunities for upstream equipment suppliers.

CM Batteries: Leading the Solid-State Frontier
As a pioneer in the customized battery sector, CM Batteries is actively investing in the research and customization of next-generation Solid-State Batteries.

Cutting-edge R&D: CMB focuses on sulfide all-solid-state technology, aiming to provide lighter battery solutions with higher energy densities (targeting 450 Wh/kg+) for UAVs, medical devices, and specialized industrial equipment.

Safety Benchmarking: Integrated with CMB’s proprietary intelligent thermal management systems, our solid-state battery packs maintain extreme thermal stability in harsh environments, effectively eliminating safety concerns associated with traditional lithium batteries.

Flexible Customization: For startups and high-tech research projects, CMB offers flexible customization services ranging from semi-solid to all-solid-state batteries, helping clients seize market opportunities before the 2027 technical breakout.

Looking for high-density, high-safety power solutions for your next project? CMB provides expert technical consultation for your solid-state battery selection.

Case Study and Optimization of Low-Temperature Heating for Power Battery Packs

CM Batteries — Sun, 11 Jan 2026 19:14:40 +0000

In industrial energy storage sectors, extreme cold is a "performance killer." Low temperatures lead to reduced electrochemical activity and increased electrolyte viscosity, causing a sharp decline in charging and discharging capabilities. As a leading provider of [Low-Temperature Battery]solutions, CM Batteries has conducted in-depth research into heating technologies to overcome bottlenecks such as slow temperature rise, high energy consumption, and poor temperature uniformity.

Testing Methods for Power Battery Low-Temperature Heating The performance of the Battery Thermal Management System (BTMS) is critical for reliable operation in frigid conditions. CMB strictly follows international standards to evaluate heating performance across multiple dimensions.

1.1 Classification of Heating Performance Tests

Testing is primarily divided into low-temperature charging heating and low-temperature discharging heating. These tests are conducted in climate chambers at a standard temperature of -20°C or the minimum operating temperature specified by the manufacturer.

1.2 Key Physical Quantities Monitored

During testing, the following data points are recorded:
Temperature Rise Rate (°C/min): The core metric for heating speed.
Temperature Uniformity: The difference between the highest and lowest temperatures within the battery pack.
Energy Consumption (kWh): Assessing the impact on total vehicle range.

Comparative Analysis of Different Heating Methods CMB’s laboratory data compares the effectiveness of external, internal, and liquid heating methods.

2.1 External Heating (Heating Films/Plates)
Mechanism: Attaching heating films or plates to the sides of cells or modules.
Data: A temperature rise rate of 0.8–1°C/min. Heating from -20°C to 10°C takes approximately 30–40 minutes.
Pros/Cons: Low system complexity, but internal temperature differences can reach 5–10°C.

2.2 Internal Heating (Pulse Heating)
Mechanism: Using high-frequency pulse currents to stimulate heat generation within the battery.
Data: A rapid rate of 3–5°C/min. Heating from -20°C to 10°C takes only 6–10 minutes.
Pros: Highest energy efficiency and excellent uniformity (temperature delta within 3°C).

2.3 Liquid Heating
Mechanism: Heating a liquid coolant that circulates through the battery pack.
Data:A rate of 1.5–2.5°C/min. Heating takes 12–20 minutes.
Pros:Best stability and uniformity for large-scale power systems.

Performance Degradation and Safety Risks

Without an effective heating system, power batteries at -30°C suffer severe degradation:

Capacity & Power: Charging capacity drops to ~10% and discharge power to ~30% of room-temperature levels.
Lithium Plating: Low-temperature charging risks the formation of lithium dendrites, which can pierce the separator and cause internal short circuits or thermal runaway.

Optimization Solutions by CM Batteries To address technical bottlenecks, CM Batteries has implemented the following optimization strategies:

4.1 Integrated Pulse and Film Heating
CMB utilizes high-performance Low-Temperature Battery cells that support discharge at temperatures as low as -50°C. Our systems can integrate heating films with intelligent BMS pulse logic to ensure rapid recovery from extreme cold.

4.2 Advanced Internal Self-Heating Structure
By integrating customized heating elements (such as Silicone or Kapton heaters) directly within the pack, CMB reduces the heat transfer path and maximizes thermal efficiency.

4.3 Smart BMS Thermal Management
Our proprietary BMS (supporting CANBUS, RS485, and Bluetooth) provides multi-level temperature monitoring. This ensures that the heating function is activated only when necessary, preventing local overheating and consistency deterioration.

Future Outlook The future of battery thermal management lies in material innovation and intelligent control. CM Batteries continues to develop next-generation electrolytes and "Vehicle-to-Charger" interconnected heating systems to provide reliable power for medical, industrial, and subsea applications in the world's harshest climates.

Case Study and Optimization of Low-Temperature Heating for Power Battery Packs

CM Batteries — Sun, 11 Jan 2026 19:06:47 +0000

In industrial energy storage sectors, extreme cold is a "performance killer." Low temperatures lead to reduced electrochemical activity and increased electrolyte viscosity, causing a sharp decline in charging and discharging capabilities. As a leading provider of Low-Temperature Battery solutions, CM Batteries has conducted in-depth research into heating technologies to overcome bottlenecks such as slow temperature rise, high energy consumption, and poor temperature uniformity.

Testing Methods for Power Battery Low-Temperature Heating The performance of the Battery Thermal Management System (BTMS) is critical for reliable operation in frigid conditions. CMB strictly follows international standards to evaluate heating performance across multiple dimensions.

1.1 Classification of Heating Performance Tests

1.2 Key Physical Quantities Monitored

During testing, the following data points are recorded:

Temperature Rise Rate (°C/min): The core metric for heating speed.
Temperature Uniformity: The difference between the highest and lowest temperatures within the battery pack.
Energy Consumption (kWh): Assessing the impact on total vehicle range.

Comparative Analysis of Different Heating Methods CMB’s laboratory data compares the effectiveness of external, internal, and liquid heating methods.

Performance Degradation and Safety Risks

Without an effective heating system, power batteries at -30°C suffer severe degradation:

Optimization Solutions by CM Batteries To address technical bottlenecks, CM Batteries has implemented the following optimization strategies:

4.1 Integrated Pulse and Film Heating
CMB utilizes high-performance [Low-Temperature Battery](https://cmbatteries.com/project/low-temperature-battery/) cells that support discharge at temperatures as low as -50°C. Our systems can integrate heating films with intelligent BMS pulse logic to ensure rapid recovery from extreme cold.

Future Outlook The future of battery thermal management lies in material innovation and intelligent control. CM Batteries continues to develop next-generation electrolytes and "Vehicle-to-Charger" interconnected heating systems to provide reliable power for medical, industrial, and subsea applications in the world's harshest climates.

21700 vs. 18650 Lithium Batteries: A Data-Driven Comparative Guide

CM Batteries — Tue, 09 Dec 2025 06:37:57 +0000

The 21700 lithium-ion cell rapidly gained traction in the electric vehicle market due to its high energy density and low cost, soon becoming a strong contender to replace the widely used 18650 cell. Studies show that 21700 cells deliver up to 35% higher energy density compared with 18650 cells using the same material system.

While the 18650 cell has been extensively studied, published research on the 21700 format remains limited. Market testing also shows substantial performance variations among different 21700 cell models, highlighting the importance of careful model selection.

Most previous studies compare different formats, comparing 18650 vs. 21700 energy, capacity, energy density, internal resistance, thermal properties, and cost. Thomas Waldmann further compared electrochemical, thermal, and geometric properties between classic 18650 and new 21700 cells.
However, direct comparisons between cells of the same format but different models remain scarce.

Given the abundant research on the thermodynamic characteristics of 18650 cells, a deeper investigation into the differences and similarities between different 21700 models is both necessary and valuable.

This study conducts a multi-scale comparative analysis of two different 21700 lithium-ion battery models with identical specifications. Using thermocouple sensors, we measured surface temperature under different discharge rates and ambient temperatures, supplemented by voltage and capacity analysis to obtain a comprehensive thermodynamic profile.

Experimental Setup 1.1 Battery Samples

Two models of 21700 lithium-ion batteries produced by the same manufacturer were selected to ensure consistent production technology and quality control. Their basic parameters are shown in Table 1.

Table 1. Basic parameters of the lithium-ion cells.

1.2 Experimental Instruments

The experimental setup includes:

21700 lithium-ion cells

Battery charger

330-00A temperature-controlled chamber

Three K-type thermocouples

RS20K-C thermocouple transmitter

TEC-80K high-power electronic load

Custom battery test fixture

Battery internal resistance tester

Two USB-to-485 data acquisition units

Laptop for data processing

The temperature chamber simulates controlled ambient environments.
The RS20K-C transmitter collects battery surface temperature.
The TEC-80K load provides constant-current discharge at various C-rates while recording voltage and current.

Table 2. Specifications of instruments used in the experiments.

1.3 Experimental Method

To ensure sample consistency, internal resistance screening was first performed.
Fifty units of Model A and Model B were tested (resistance measurement diagram: Figure 1).

Cells were then capacity-tested, and five units from each model with similar capacity and internal resistance were selected for full thermodynamic analysis (Figure 2).

Experimental procedure

Charge each cell to 4.2 V and rest for 1 hour.

Place the cell in the climatic chamber and rest another hour.

Begin discharge testing once the cell temperature is within ±1 °C of the set value.

Perform discharge tests at 0.5C–2C and 25 °C–40 °C ambient conditions.

Results and Discussion 2.1 Internal Resistance Comparison

Internal resistance data for 50 units of each model are shown in Figure 3.

Model B cells exhibit consistently lower resistance than Model A.

Average internal resistance:

Model A: 15.3 mΩ

Model B: 6.6 mΩ

Average difference: 8.7 mΩ.

2.2 Voltage Drop at Different Ambient Temperatures

The 0.5C discharge voltage curves for two sample models (40T and 50G) at various temperatures are shown in Figure 4.

Key findings:

At the beginning (DOD = 0–0.1), voltage drops rapidly as the cell transitions from float-charge to open-circuit voltage.

Mid-stage discharge (DOD = 0.1–0.8) remains stable.

End-stage discharge (DOD = 0.8–1.0) drops sharply to cutoff.

Higher ambient temperature results in higher discharge voltage due to increased electrolyte ionic mobility.

At all temperatures, 50G voltage > 40T voltage, indicating higher output power.

2.3 Capacity Under Different Discharge Rates

At 25 °C, capacity at 0.5C–2C is shown in Figure 5:

Increasing discharge rate reduces capacity in both models.

50G capacity declines more sharply at high C-rates (1C–2C).

Therefore, 40T offers better capacity stability across discharge rates.

2.4 Capacity Under Different Ambient Temperatures

Capacity at 0.5C and different temperatures is shown in Figure 6.

Findings:

Capacity increases with temperature for both models.

50G exhibits greater temperature-based capacity gain, achieving higher capacity at 30–40 °C compared with 40T.

2.5 Surface Temperature Rise Under Different Conditions

Surface temperature profiles under 1C discharge at various temperatures are shown in Figure 7.

Temperature rise follows a pattern:

Rapid rise (initial internal resistance heat)

Slower rise (stable mid-discharge)

Accelerated rise (temperature-induced resistance increase)

Across all conditions, 40T temperature rise > 50G, indicating that 50G has better thermal uniformity.

Temperature rise under different C-rates at 25 °C is shown in Figure 8:

Higher discharge current produces faster and higher temperature rise.

Maximum temperatures:

40T: 35.3 °C → 66.2 °C (0.5C → 2C)

50G: 32.3 °C → 58.1 °C

At 1.5C, peak temperature difference reaches 10.5 °C (50G cooler).

Thus, 50G consistently runs cooler than 40T at all discharge rates.

Conclusions

This study provides a detailed thermodynamic and electrical comparison of two different 21700 lithium-ion cell models with identical specifications.

Key conclusions:

Internal Resistance

Model A exhibits 8.7 mΩ higher average resistance than Model B.

Voltage & Power Output

At identical conditions, 50G cells maintain higher discharge voltage, indicating higher output power.

Capacity Performance

At increasing C-rates, 40T shows better capacity stability.

At higher temperatures, 50G delivers greater capacity increase, performing better in warm environments.

BMS vs. PCM: An In-Depth Comparison of Lithium-ion Battery Protection Systems

CM Batteries — Wed, 12 Nov 2025 06:31:49 +0000

In modern battery technology, BMS (Battery Management System) and PCM (Protection Circuit Module) are both key components ensuring battery safety, performance, and reliability. Especially in lithium-ion battery applications, they each play a crucial role. As a professional lithium-ion battery manufacturer, understanding the differences and advantages of these two technologies is essential. This article will provide an in-depth analysis of the functions, differences, and applicable scenarios of BMS and PCM from an engineering perspective, helping engineers and technicians make the best choice.

I. What is a BMS (Battery Management System)?
A BMS (Battery Management System) is an integrated electronic system primarily used to monitor and manage the state of each individual cell in a battery pack, ensuring that the battery operates under safe and efficient conditions. In addition to basic battery protection functions, a BMS also includes complex functions such as charge management, equalization management, temperature monitoring, and health diagnostics. A BMS typically consists of multiple modules, including hardware and software components, capable of interacting with other electronic components of the battery to control the charging and discharging process and optimize battery lifespan.

Main functions of a Battery Management System (BMS):
Battery Voltage Monitoring: Real-time monitoring of the voltage of each individual battery cell to prevent overcharging or over-discharging.

Current Monitoring: Ensuring that the charging and discharging current of the battery is within a safe range to prevent overheating or damage due to excessive current.

Temperature Monitoring: Temperature management is crucial for the safety of lithium batteries. The BMS monitors battery temperature in real time to prevent performance degradation caused by overheating or low operating conditions.

Battery Balancing Management: The BMS balances the voltage of each individual battery cell in the battery pack to ensure consistent charge levels and prevent battery pack imbalance.

State of Charge (SOC) and State of Health (SOH) Estimation: The BMS uses precise algorithms to estimate the remaining charge (SOC) and state of health (SOH) of the battery to provide users with accurate battery status information.

Communication and Alarms: The BMS can interact with external devices via communication protocols such as CAN and UART, providing real-time data and issuing warnings when battery abnormalities occur.

II. What is a PCM (Protection Circuit Module)?

A PCM (Protection Circuit Module) is a basic implementation of lithium battery protection circuits. It typically consists of protection circuits for individual battery cells and the battery pack itself, primarily used to prevent safety issues such as overcharging, over-discharging, short circuits, and overheating during battery cell use. The PCM has a relatively simple structure, usually composed of a few electronic components and protection circuits, focusing on battery safety protection.

Main functions of a PCM:

Overcharge protection: Prevents the battery voltage from exceeding the maximum safe voltage limit, avoiding thermal runaway or performance degradation due to overcharging.

Over-discharge protection: Prevents the battery voltage from dropping too low, avoiding damage caused by deep discharge.

Short circuit protection: Prevents short circuits, avoiding excessive current that could lead to battery overheating or even fire.

Over-temperature protection: Monitors battery temperature using a temperature sensor, preventing excessively high temperatures from harming battery performance and safety.

III. Core Differences Between BMS and PCM

There are significant differences between BMS and PCM in terms of function, complexity, and application scope.

Functional Scope

BMS: More comprehensive in function, including charge/discharge management, battery balancing, health monitoring, and communication, in addition to battery protection. BMS not only protects the battery but also provides data analysis to indicate battery operating status, predict remaining battery life, and assess battery health.

PCM: More focused on protecting the battery from overcharging, over-discharging, short circuits, and overheating. Its primary focus is preventing battery safety threats, but it does not involve battery health management or performance optimization.

Complexity and Cost

BMS: Due to its multiple functional modules, BMS is typically complex and expensive. It requires the integration of various sensors and control units, and sophisticated software support for intelligent monitoring and data analysis. Therefore, BMS is typically used in demanding applications such as electric vehicles (EVs), energy storage systems, and high-power battery packs.

PCM: Simple in structure and low in cost, primarily focused on basic battery protection functions, requiring no complex calculations or advanced features. PCM is typically used in low-power applications or applications with lower safety requirements.

Application Scenarios

BMS: BMS is widely used in electric vehicles, power tools, energy storage systems, drones, robots, and other fields, suitable for high-power, high-performance applications requiring long-term operation. It provides comprehensive battery monitoring and management, optimizing battery lifespan.

PCM: PCM is suitable for applications with high safety requirements but not complex management, such as some portable electronic products (e.g., electric bicycles, power tools). PCM primarily provides basic safety protection, ensuring the battery is not damaged by overcharging or over-discharging.

Communication and Intelligence

BMS: Supports intelligent communication, such as CAN and UART, enabling real-time data interaction with external devices or systems. BMS also provides users with detailed battery data analysis to help them make informed decisions.

PCM: Lacking intelligent communication capabilities, it only provides simple battery protection and typically does not involve interaction with external devices.

IV. When to Choose a BMS or PCM?

As a professional lithium battery manufacturer, the key to choosing between a BMS and PCM lies in application requirements, cost considerations, and system complexity.

Choosing a Battery Management System (BMS): If the application requires long-term operation, high-performance battery management, battery pack balancing management, battery health monitoring, and real-time data interaction with other systems, then a BMS is more suitable. BMS is well-suited for complex systems such as electric vehicles, large energy storage systems, and drones.

Choosing a Battery Management System (PCM): If the application has simpler battery protection requirements, only needing overcharge, over-discharge, short-circuit, and over-temperature protection, and is cost-sensitive, such as some low-power consumer electronics and portable battery devices, then a PCM may be a more economical solution.

V. Summary

In lithium battery design and applications, BMS and PCM each have their advantages. BMS provides a more comprehensive and intelligent battery management solution, suitable for applications with high requirements for battery performance, lifespan, and safety, while PCM excels in cost-effectiveness and simple protection, suitable for applications with lower battery management requirements. As a lithium battery manufacturer, understanding the differences between these two technologies helps us provide customers with the most suitable battery management solutions to ensure safe, efficient, and long-life battery operation.