How to Calculate Battery Pack Voltage: A Simple Guide for LiFePO4 and Ternary Lithium Batteries

Battery voltage is one of the most important parameters when designing or selecting a rechargeable battery pack. Whether the battery is used in a POS terminal, medical device, portable equipment, smart lighting system, energy storage device, or industrial application, the voltage must match the electrical requirements of the product.

For engineers, product developers, and procurement teams, understanding how battery voltage is calculated can help avoid common design problems, such as insufficient output power, unstable operation, reduced runtime, or compatibility issues with chargers and control systems.

This article explains how battery pack voltage is calculated, using two common lithium battery chemistries: LiFePO4 batteries and ternary lithium batteries.

1. Basic Voltage of Common Lithium Battery Cells

A battery pack is usually built by connecting multiple cells in series and parallel. Before calculating the total battery pack voltage, it is important to understand the voltage of a single cell.

LiFePO4 Battery Cell Voltage

LiFePO4, also known as lithium iron phosphate, is widely used in applications that require high safety, long cycle life, and stable discharge performance.

Typical voltage values of a single LiFePO4 cell are:

• Fully charged voltage: 3.65V
• Nominal voltage: 3.20V
• Discharged voltage: 2.50V

LiFePO4 batteries are often selected for energy storage systems, industrial equipment, backup power, electric mobility, and applications where safety and cycle life are priorities.

Ternary Lithium Battery Cell Voltage

Ternary lithium batteries usually refer to lithium-ion batteries using NCM or NCA chemistry. They are commonly used when higher energy density and compact size are required.

Typical voltage values of a single ternary lithium cell are:

• Fully charged voltage: 4.20V
• Nominal voltage: 3.70V
• Discharged voltage: 3.00V

Ternary lithium batteries are widely used in consumer electronics, medical devices, POS terminals, smart wearables, Bluetooth audio products, mobile lighting, beauty devices, and many portable electronic products.

2. What Does “Battery Pack in Series” Mean?

When battery cells are connected in series, the voltage increases while the capacity remains the same.

For example, if one LiFePO4 cell has a nominal voltage of 3.2V, then a 20-series battery pack will have:

3.2V × 20 = 64V nominal voltage

This is why battery packs are often described as 13S, 16S, 17S, 20S, or 24S. The letter “S” means the number of cells connected in series.

A higher series count means a higher battery pack voltage.

3. How to Calculate Battery Pack Voltage

The formula is simple:

Battery Pack Voltage = Single Cell Voltage × Number of Cells in Series

This formula can be used to calculate fully charged voltage, nominal voltage, and discharged voltage.

For example, if we design a LiFePO4 battery pack with 20 cells in series:

• Fully charged voltage: 3.65V × 20 = 73.0V
• Nominal voltage: 3.20V × 20 = 64.0V
• Discharged voltage: 2.50V × 20 = 50.0V

Although the battery may be called a “60V battery pack,” its actual voltage changes during charging and discharging. This is normal for lithium batteries.

4. Common LiFePO4 Battery Pack Voltages

LiFePO4 battery packs are often configured according to application requirements. Below are several common voltage configurations.

These configurations are commonly used in applications that require safer chemistry, long cycle life, and stable output performance.

5. Common Ternary Lithium Battery Pack Voltages

Ternary lithium battery packs use a higher single-cell voltage, so the required series count is different from LiFePO4.

Because ternary lithium batteries have higher energy density, they are often used in compact battery pack designs where size and weight are important.

6. Why Nominal Voltage Is Not the Same as Actual Voltage

Many customers ask why a battery labeled as 48V, 60V, or 72V does not always show exactly that voltage when measured.

The reason is simple: lithium battery voltage changes according to state of charge.

When the battery is fully charged, the voltage is higher. During use, the voltage gradually drops. When the battery reaches its lower voltage limit, the BMS will usually cut off discharge to protect the cells from over-discharge.

For example, a 48V LiFePO4 battery pack may reach 58.4V when fully charged and drop to around 40.0V when discharged. This does not mean the battery is defective. It is part of the normal working voltage range.

7. Why Voltage Calculation Matters in Battery Pack Design

Correct voltage design is essential for battery-powered products. If the voltage is too low, the device may not start properly or may not deliver enough power. If the voltage is too high, it may damage the device, charger, controller, or electronic components.

Voltage design affects:

• Device compatibility
• Charger selection
• BMS configuration
• Motor or controller performance
• Runtime and power output
• Safety protection settings
• Certification and testing requirements
• Long-term product reliability

This is why battery pack design should not only focus on capacity. Voltage, current, cell chemistry, protection design, temperature range, and application environment must all be considered together.

8. LiFePO4 vs Ternary Lithium: Which One Should You Choose?

Both LiFePO4 and ternary lithium batteries are widely used, but they are suitable for different applications.

LiFePO4 Battery Advantages

LiFePO4 batteries are known for safety, thermal stability, long cycle life, and strong durability. They are suitable for products where long service life and safety are more important than compact size.

Common applications include:

• Energy storage systems
• Industrial power equipment
• Backup power systems
• Electric mobility applications
• Outdoor power devices
• High-safety battery systems

Ternary Lithium Battery Advantages

Ternary lithium batteries provide higher energy density, lighter weight, and more compact structure. They are suitable for portable devices that need longer runtime in limited space.

Common applications include:

• POS terminals
• Medical devices
• Smart wearables
• Bluetooth audio products
• Beauty devices
• Smart home devices
• Portable lighting products
• Consumer electronics

The best battery chemistry depends on the product’s voltage, capacity, size, weight, discharge rate, charging requirements, and safety standards.

9. Gloflux Custom Battery Pack Support

At Gloflux, we help customers design and manufacture lithium battery solutions based on real application requirements. Instead of simply providing standard batteries, our engineering team evaluates the full electrical and mechanical needs of each project.

Gloflux supports:

• Custom lithium-ion battery packs
• Li-polymer battery solutions
• LiFePO4 battery pack development
• Cylindrical cell battery packs
• Rechargeable AA and AAA battery solutions
• Replaceable battery pack design
• BMS and protection circuit integration
• Custom voltage and capacity design
• Connector, wire, label, housing, and packaging customization
• Certification support for global markets

Whether your product requires a compact 3.7V battery, a multi-cell battery pack, a high-capacity rechargeable solution, or a custom battery system with specific voltage requirements, Gloflux can provide engineering support from sample development to mass production.

10. Final Thoughts

Battery pack voltage is calculated by multiplying the voltage of a single cell by the number of cells connected in series. However, battery design is not only about simple voltage calculation. A reliable battery pack must also consider chemistry, BMS protection, charging method, discharge current, operating temperature, cycle life, product structure, and safety certification.

Understanding the difference between LiFePO4 and ternary lithium battery voltage helps product developers make better design decisions at the early stage.

If you are developing a battery-powered product and need help with voltage selection, battery pack design, or custom lithium battery manufacturing, Gloflux can help you build a safer, more reliable, and production-ready battery solution.