Whether holding inventory in a warehouse or shipping products internationally, ambient storage conditions and State-of-Charge (SoC) are the defining factors in battery safety, performance, and longevity. For most battery chemistries, cool and dry conditions around 15°C (59°F) are recommended for long-term storage. Depending on battery chemistry and product specifications, allowable storage temperatures may range from –40°C to 50°C for short-term exposure.
Based on industry testing standards, this guide provides a clear breakdown of storage protocols for Lithium-ion, Sealed Lead Acid (SLA), Nickel-based, and Alkaline batteries, as well as the latest IATA regulations regarding air transportation.

1. Lithium-ion (Li-ion): Ideal 40% SoC Storage and Sleep Mode Prevention

Lithium-ion chemistries are sensitive to voltage levels and ambient heat during long-term storage. Storing a Li-ion pack at 100% SoC in warm environments drastically accelerates permanent, unrecoverable capacity loss.

• Optimal Storage State: approximately 40% SoC (typically 3.7–3.85V per cell depending on chemistry). This level minimizes chemical stress while allowing sufficient leeway for self-discharge.
• Over-discharge & Copper Shunts: Most Li-ion batteries should not be stored below their manufacturer-specified discharge cutoff voltage, which is typically between 2.5V and 3.0V per cell. Many protection circuits may enter sleep mode when cell voltage approaches approximately 2.5VIf left below 2.0V/cell for an extended period, copper current collectors begin to dissolve, forming copper shunts that cause internal micro-shorts and severe thermal runaway risks upon recharge.

Engineering Tip: Before taking open-circuit voltage (OCV) readings, allow the battery to rest for 90 minutes to eliminate voltage bounce-back (the “rubber band effect”).

2. Air Transport Compliance (AirShip): The 30% SoC Mandate

In compliance with IATA and FAA regulations, all standalone or removable Lithium-ion battery packs transported via air cargo must be shipped at a maximum of 30% State-of-Charge.

• Safety Rationale: Keeping batteries at or below 30% SoC significantly reduces volatility and energy release potential in the rare event of a thermal anomaly during transit.
• Automated Shipping Prep: Modern industrial chargers and BMS platforms feature dedicated “AirShip” programs. Using Coulomb counting or advanced Kalman filters, these systems automatically charge or discharge packs to the precise 30% SoC threshold prior to packaging.

3. Sealed Lead Acid (SLA): Preventing Sulfation and The 70% SoC Recharging Rule

Sealed lead acid batteries can typically be stored for 6–24 months depending on storage conditions, provided they are monitored to prevent sulfation—an oxidation layer that builds up on negative plates due to low charge states.

• Recharge Threshold: Apply a topping charge as soon as the battery drops to approximately 70% (2.07V/cell OCV or 12.42V for a 12V pack; specific gravity ~1.218).
• Sulfation Reactivation: For small SLA cells (such as Hawker Cyclone) affected by prolonged storage, recovery is often possible by applying elevated voltage with a strictly limited low current to dissolve sulfate crystals back into active material.

4. Nickel-Based and Alkaline Batteries: Storage & Capacity Priming

• Nickel-Based (NiMH / NiCd): Store at approximately 30–50% SoC or in a fully discharged state (for single cells). Nickel-metal-hydride can be stored for 3–5 years. Capacity drop during storage is largely reversible through 1–3 priming (charge/discharge) cycles.
• Primary Alkaline Batteries: Alkaline batteries store well at cool room temperatures and ~50% relative humidity for up to 10 years. Avoid prolonged freezing conditions unless specified by the manufacturer, as extremely low temperatures may affect seals and performance.

Key Takeaways for Warehouse and Fleet Management Environment

Control: Keep storage areas cool (ideally 15°C / 59°F) and dry (~50% relative humidity). Avoid direct sunlight.
Li-ion Protocols: Store at 40% SoC for long-term inventory; in accordance with IATA Dangerous Goods Regulations, standalone lithium-ion batteries classified as UN3480 transported by air must not exceed 30% SoC.
Routine Maintenance: Check lead-acid voltages every 3–6 months and top-charge immediately if the pack drops below 12.42V.

When developing a high-performance device, a custom battery is far more than a power source. It directly influences system performance, safety, product lifespan, and regulatory compliance. For medical devices, industrial equipment, robotics, and IoT products, standard batteries often cannot meet demanding application requirements

At Hypercell, our custom battery solutions follow a highly disciplined, end-to-end engineering methodology. Backed by over 19 years of experience, here is our streamlined 6-step blueprint for bringing your power solution from initial concept to certified production.

Step 1: Discovery & Requirements Gathering

Every successful battery project begins with absolute clarity. Our engineering team collaborates directly with you to establish a comprehensive technical envelope:

Electrical Profiles:Nominal voltage, peak current draw, dynamic power profiles, charging requirements, and targeted capacity.
Mechanical Constraints:Exact 3D dimensions, enclosure materials, and connector interfaces.
Environmental Tolerances: Operating temperatures, vibration levels, humidity conditions, and ingress protection (IP ratings).

Step 2: Integrated Cells, Smart BMS & Mechanical Design

Once specifications are locked, we initiate the core design phase. We optimize the battery cell, Battery Management System (BMS), and mechanical enclosure as an integrated system.

1. Cell & Chemistry Selection: We source from Tier-1 manufacturers, balancing energy density, cost, and lifecycle. Options include high-capacity Li-ion ,LiFePO4 or NiMH.
2. Smart BMS Engineering: Protection functions include overcharge, over-discharge, overcurrent, short circuit, and temperature monitoring.We design custom PCBAs with precise State-of-Charge (SOC) tracking and integrated communication protocols (I2C, SMBus, CAN bus, or Modbus) so your device can read real-time battery diagnostics.
3. hermal & Enclosure Design: Using 3D CAD, we engineer rugged enclosures focused on Thermal Management. We simulate stress to prevent thermal runaway propagation under heavy discharge curves.

Step 3: Rapid Prototyping & Rigorous Testing

Before committing to production-grade tooling, we construct functional, high-fidelity prototypes. Using in-house 3D printing and rapid spot-welding technology, we put the prototype through grueling physical and electrical stress tests:

Thermal Cycle Testing: Verifying pack integrity under extreme temperature swings.
Load & Capacity Testing: Simulating real-world device duty cycles to verify runtime.
Drop & Vibration Testing: Validating mechanical durability for industrial and military standards.

Step 4: Regulatory Compliance & Safety Certification

Navigating global approvals is one of the biggest bottlenecks in product launches. We partner with accredited third-party labs to secure crucial compliance certifications for your target market.

Step 5: Scaled Production & Quality Control

Once validated, your project transitions seamlessly into our advanced manufacturing facilities, where quality and consistency are prioritized:

Cell Matching: Sorting and pairing cells with identical internal resistance and capacity to maximize pack lifespan.
100% Automated EOL Testing: Every pack undergoes automated safety, protocol communication, and functional testing before packaging.
Full Traceability: End-to-end component tracking from BMS chipsets to individual lithium cells.

Step 6: Global Logistics & Class 9 Hazmat Compliance

The process doesn’t end when production finishes. Shipping lithium batteries requires navigating complex global regulatory frameworks, as they are classified as Class 9 Dangerous Goods (Hazmat).

Compliant Packaging: We design and supply UN-certified packaging (compliant with IATA, ADR, and IMDG codes).
Regulatory Documentation: We manage UN38.3 test summaries, Material Safety Data Sheets (MSDS), and shipper declarations.
Lifecycle Support: Ongoing supply chain management, future design revisions, and obsolescence tracking for critical components.

At Hypercell, we combine over 19 years of engineering expertise with state-of-the-art assembly to deliver safe, smart, and resilient power solutions.

Ready to kickstart your next project? Contact our sale today to discuss your custom power requirements!

Lithium-ion battery performance is not only determined by chemistry but also by how the internal electrodes are assembled. Among the most widely used manufacturing methods, stacking (lamination) and winding (jelly-roll) define the core structure of a battery cell.

While cylindrical batteries typically use winding technology and pouch cells mainly use stacking, prismatic batteries can adopt either process depending on performance and cost requirements.

Understanding these two technologies is essential for selecting the right battery solution for applications such as electric vehicles, medical devices, robotics, and consumer electronics.

Lithium-Ion Battery Manufacturing Overview

The battery manufacturing process generally includes four key stages:

• Electrode slurry mixing
• Coating, drying, calendaring, and slitting
• Cell assembly (stacking or winding)
• Electrolyte filling, formation, and grading

Among these, cell assembly is the most critical stage, as it directly determines the internal structure and performance of the battery.

What Is Winding Technology?

Winding technology, also known as the jelly-roll process, is the most mature lithium-ion battery assembly method.

In this process:

• Positive electrode
• Separator
• Negative electrode

are continuously wound into a cylindrical or prismatic structure.

This creates a spiral internal structure commonly referred to as a “jelly roll.”

Applications of Winding Batteries

• 18650 cells
• 21700 cells
• 4680 cylindrical cells
• Power tools
• Consumer electronics
• Energy storage system

Advantages of Winding Technology

1. Highly mature manufacturing process
Winding has been developed over decades and is widely standardized.

2. High production efficiency
Continuous manufacturing enables large-scale automation.

3. Lower cost
Mature equipment and stable yield reduce overall production cost.

4. Excellent consistency
Suitable for mass production of standardized battery cells.

Limitations of Winding Technology

• Internal stress concentration in jelly-roll structure
• Limited space utilization due to cylindrical geometry
• Slight constraints in energy density improvement

What Is Stacking Technology?

Stacking technology assembles electrodes by cutting them into individual sheets and stacking them layer by layer.

The typical structure is:

Positive electrode → Separator → Negative electrode → Separator → repeated stacking

This creates a flat and uniform electrode structure.

Applications of Stacked Batteries

• High voltage batteries
• Blade batteries
• High-energy-density prismatic batteries
• Drones
• Medical devices
• High-performance robotics

Advantages of Stacking Technology

1. Higher energy density potential
Better space utilization increases active material ratio.

2. Improved thermal management
More uniform heat distribution reduces hotspots.

3. Longer cycle life
Lower mechanical stress improves durability.

4. Enhanced safety performance
Reduced internal resistance and improved thermal stability.

5. Better fast-charging capability
Lower polarization improves charge acceptance.

Limitations of Stacking Technology

• Higher equipment investment
• Lower production efficiency compared to winding
• More complex process control requirements

Stacking vs Winding: Key Differences

Why Stacking Offers Higher Energy Density

Stacking technology improves energy density through:

1. Better space utilization

No central void like cylindrical winding structures.

2. Higher active material ratio

Less inactive structural space inside the cell.

3. Uniform electrode alignment

Improves ion transport efficiency.

4. Reduced internal resistance

Shorter electron and ion pathways.

Fast Charging Performance Comparison

Fast charging performance is increasingly important in modern applications.

Stacked cells generally perform better because:

• More uniform current distribution
• Lower internal polarization
• Better thermal stability during high-rate charging

This makes stacking ideal for:

• Electric vehicles
• Drones
• High-performance industrial systems

Safety Considerations

Battery safety is influenced by both design and manufacturing precision.

Key safety factors include:

• Burr control during electrode cutting
• Separator integrity
• Internal short-circuit prevention
• Thermal runaway resistance

While both technologies can be safe when properly engineered, stacking often provides improved thermal uniformity in large-format cells.

Industry Applications

Winding Battery Applications

• Power tools
• Consumer electronics
• Portable energy storage
• Industrial equipment
• Cylindrical battery platforms (18650 / 21700 / 4680)

Stacking Battery Applications

• Electric vehicles
• High-end drones
• Medical devices
• Robotics systems
• High-energy-density prismatic batteries

Industry Trends

The lithium battery industry is evolving toward higher energy density and improved safety.

Key trends include:

• Growth of large-format prismatic batteries
• Increased adoption of stacking technology in EVs
• Continued dominance of cylindrical winding cells in consumer and industrial applications
• Development of high-speed stacking equipment

Companies such as Tesla continue to use winding-based cylindrical platforms like 4680 cells, while manufacturers like BYD promote blade battery designs based on stacked architectures.

How Hypercell Selects the Right Technology

At Hypercell, battery design is application-driven rather than technology-driven.

We evaluate multiple factors:

• Energy density requirements
• Discharge rate
• Cycle life targets
• Size and weight constraints
• Operating environment
• Cost efficiency

Based on these parameters, we select the most suitable cell architecture—whether winding or stacking—to ensure optimal performance for each application.

Frequently Asked Questions (FAQ)

1.Is stacking better than winding?

There is no absolute “better” option. The best choice depends on application requirements.

2.Why do cylindrical batteries use winding?

Because winding is highly efficient and well-suited to cylindrical geometry.

3.Why are pouch batteries usually stacked?

Stacking maximizes space utilization and improves energy density.

4.Which technology lasts longer?

Stacking may offer longer cycle life due to reduced mechanical stress, depending on design and usage conditions.

5.Is stacking more expensive?

Yes, due to higher equipment cost and lower production efficiency.

6.Can both technologies be used in prismatic batteries?

Yes, prismatic batteries can adopt either stacking or winding depending on design goals.

7.Which is better for fast charging?

Stacking generally performs better in high-rate charging applications.

Conclusion

Stacking and winding are two fundamental lithium-ion battery manufacturing technologies, each with distinct advantages.

Winding offers cost efficiency, mature production, and high scalability.
Stacking provides higher energy density, better thermal performance, and improved electrochemical stability.

The optimal choice depends entirely on application requirements rather than a universal superiority of one technology.

At Hypercell, we provide customized lithium battery solutions tailored to performance, safety, and cost objectives across diverse industries.

A modern Battery Management System (BMS) performs far more than basic battery protection. In today’s rechargeable battery systems, smart BMS technology continuously monitors battery conditions, manages charging and discharging behavior, and helps improve battery safety, efficiency, and lifespan.

For lithium battery packs used in consumer electronics, medical devices, industrial equipment, and IoT products, a reliable Battery Management System is essential for stable and safe operation.

Overcharge Protection Function

Overcharging is one of the most common causes of lithium battery damage.

When battery voltage exceeds safe charging limits, excessive heat generation may occur, increasing the risk of battery swelling, capacity degradation, or thermal failure.

A smart BMS continuously monitors charging voltage and automatically disconnects charging when abnormal voltage levels are detected.

This protection function helps improve lithium battery safety and long-term reliability.

Overdischarge Protection Function

Excessive discharge may permanently damage lithium battery cells and reduce battery cycle life.

The Battery Management System prevents battery voltage from dropping below the minimum safe operating range.

By controlling discharge conditions, the BMS helps maintain stable battery performance and protects battery health.

Overcurrent Protection Function

High current flow during charging or discharging may damage battery cells and electronic components.

A BMS monitors current conditions in real time. When excessive current is detected, the system automatically disconnects the circuit to protect the battery pack.

Overcurrent protection is especially important in high-power battery applications.

Short Circuit Protection Function

Short circuits may cause rapid temperature increase, battery failure, or safety hazards.

The Battery Management System quickly detects abnormal current flow and cuts off the electrical path to help protect both the battery and connected devices.

Fast response speed is critical for lithium battery safety protection.

Temperature Monitoring and Thermal Protection

Temperature management is one of the most important functions of a smart Battery Management System.

Lithium batteries are highly sensitive to operating temperatures. Excessive heat or extremely low temperatures may negatively affect battery performance and lifespan.

A BMS uses temperature sensors to continuously monitor thermal conditions during charging and discharging.

When abnormal temperatures are detected, the system automatically activates thermal protection mechanisms.

Cell Balancing Function

In multi-cell lithium battery packs, slight differences between cells may gradually increase during operation.

Without proper balancing, inconsistent cell voltage may reduce usable capacity and accelerate battery degradation.

Cell balancing helps maintain voltage consistency between battery cells, improving:

• Battery stability
• Energy efficiency
• Capacity utilization
• Battery lifespan
• Overall pack reliability

Cell balancing is a critical feature in smart Battery Management Systems.

Battery Monitoring and Data Collection

Modern Battery Management Systems continuously collect and analyze battery operating data.

Common monitoring parameters include:

• Battery voltage
• Current
• Temperature
• Remaining capacity
• State of Charge (SOC)
• State of Health (SOH)

Accurate battery monitoring helps optimize battery operation and improve system reliability.

Communication Functions in Smart BMS

Many intelligent Battery Management Systems support communication interfaces such as:

• CAN Bus
• SMBus
• UART
• RS485
• Bluetooth

These communication protocols allow external devices and control systems to access battery information in real time.

Communication-enabled BMS solutions are widely used in industrial equipment, smart electronics, IoT systems, and medical battery applications.

Fault Detection and Safety Protection

Advanced Battery Management Systems can identify abnormal battery conditions and provide fault warnings.

Common fault detection functions include:

• Overvoltage detection
• Undervoltage detection
• Overtemperature warning
• Communication failure detection
• Cell imbalance warning

These protection mechanisms help improve battery system safety and operational reliability.

Conclusion

A modern Battery Management System integrates multiple monitoring, protection, balancing, and communication functions to ensure safe and efficient battery operation.

From overcharge protection and thermal management to intelligent communication and fault detection, BMS technology is essential for modern lithium battery systems.

As battery applications continue to expand across multiple industries, smart Battery Management Systems will remain a key technology for safe, reliable, and high-performance energy solutions.

The sulfide-based all-solid-state battery (ASSB) route is seeing two major trends in 2025. First, its superior ionic conductivity has made it a consensus choice among researchers and industry players. Second, the commercialization process is accelerating, especially among startups, with clear progress in funding, production capacity, and market expansion.

Firm Lithium Technology Technology: A Three-Pronged Push

Firm Lithium Technology, a Chinese startup, has recently achieved several key milestones across funding, production capacity, and market expansion:

Funding: The company has completed its Series A round, backed by a subsidiary of Chaowei Power and SAIC’s investment arm.

Production Capacity: The company has completed its Series A round, backed by a subsidiary of Chaowei Power and SAIC’s investment arm.

Market Expansion: Firm Lithium has partnered with a Beijing-based premium electric motorcycle brand, marking its expansion beyond consumer electronics. The company aims to achieve vehicle integration by 2026 and scale up to passenger vehicles by 2027.

Early-Stage Competition: Carving Out Niches

Competition among solid-state battery startups is beginning to take shape. For instance, Chunli New Energy, which focuses on polymer-based ASSBs, launched a 200 MWh production line in late 2024, targeting the e-bike market.

Supply Chain Breakthroughs: Electrolyte Production Scaling Up

Upstream players are also making strides:

• Zhongke Gu’neng: Secured ton-level sulfide electrolyte orders in 2025 and established a 100-ton/year production line alongside a 100 MWh pilot line in Changzhou. The company utilizes proprietary gas-phase synthesis and wet coating technologies.

• Tianshi Kefeng: Raised tens of millions of RMB in angel funding and plans to build a tens-of-ton electrolyte powder production line in 2025, with expansion to hundred-ton scale between 2026 and 2027. Samples have already been delivered to leading players such as CATL, Gotion, and Ronbay.

• Idemitsu Kosan : Investing over JPY 21.3 billion (~USD 140 million) to build a lithium sulfide production capacity of 1,000 tons per year by June 2027, supporting Toyota’s ASSB EV launch targets for 2027–2028.

Key Observation: A “Low-to-High” Market Entry Strategy

Most sulfide-based ASSB startups are currently targeting low-speed, light-duty, or cost-insensitive applications. This pragmatic “low-to-high” strategy allows them to secure early market share and validate their technologies on smaller cells before moving into passenger EV applications.

Notably, no sulfide-focused startup has yet established a deep partnership with an automaker in China. In contrast, companies pursuing oxide-polymer composite routes—such as Tailan, Weilan, and Qingtao—have already secured strong backing from EV manufacturers through a stepwise “semi-solid to all-solid” transition strategy.

Whether sulfide-focused startups can bridge this gap and establish a leading position remains a key development to watch.

Note: This article is adapted and summarized from publicly available reporting by Gaogong Lithium Battery (GGII). The original data and viewpoints belong to GGII.