Do you know what is lithium ion cell voltage? What are the types of lithium ion cell voltage? Understanding these can help you make better purchasing choices!
Table of Contents
Nominal voltage of different types of lithium batteries
What is nominal voltage?
The nominal voltage refers to the expected average operating voltage of a battery during discharge, which provides a reference value for easy understanding and comparison of battery voltage. This value helps evaluate the compatibility between batteries and electronic devices. For example, a battery with a nominal voltage of 3.7 volts typically fluctuates around this voltage level during discharge.
Lithium ion battery nominal voltage
Lithium ion batteries are currently a common battery choice. In general, the nominal voltage of a single lithium-ion battery is about 3.6 to 3.7 volts. When these batteries are connected in series, the overall voltage will increase linearly with the increase of the number of batteries. For example, connecting three lithium-ion batteries with a nominal voltage of 3.7 volts in series will result in a total voltage of 11.1 volts (i.e. 3.7 volts multiplied by 3).
18650 battery nominal voltage
The nominal voltage of 18650 batteries is usually between 3.6 and 3.7 volts per cell. But in some special cases, especially for batteries using LiFePO4 (lithium iron phosphate) chemistry, their nominal voltage may be 3.2 volts per cell.
When these batteries are connected in series, the total voltage will increase proportionally according to the number of batteries. For example, if six batteries with a nominal voltage of 3.2 volts are connected in series, the total voltage will reach 19.2 volts (i.e. 3.2 volts multiplied by 6).
Lithium polymer battery nominal voltage
Lithium polymer (LiPo) batteries have similar performance to lithium-ion batteries, typically with a nominal voltage of approximately 3.7 volts per battery.
When lithium polymer batteries are used in series, the total voltage will increase with the number of batteries connected in series.
For example, if five lithium polymer batteries with a nominal voltage of 3.7 volts are connected in series, the total combined voltage will reach 18.5 volts (i.e. 3.7 volts multiplied by 5).
LiFePO4 battery nominal voltage
The standard voltage for lithium iron phosphate (LiFePO4) batteries is approximately 3.2 volts per cell. When these batteries are connected in series, the total voltage will increase accordingly.
The series parallel connection method, principle, and calculation of batteries are always the same.
If ten LiFePO4 batteries with a nominal voltage of 3.2 volts are connected in series, a total voltage of 32 volts will be obtained (i.e. 3.2 volts multiplied by 10).
LiFePO4 voltmeter
LiFePO4 batteries stand out for their long lifespan and superior performance. Through the voltage diagram of LiFePO4 batteries, users can clearly understand the state of charge (SoC) at different voltage levels (such as 12V, 24V, 48V).
This voltmeter is a key resource for understanding the charging level and health status of lithium iron phosphate batteries. It displays the voltage range from full charge to discharge, helping users accurately determine the real-time charging status of the battery.
As a practical guide for evaluating battery performance, optimizing efficiency, and extending the lifespan of these reliable and efficient energy solutions, the LiFePO4 voltmeter is an essential tool when using GycxSolar brand LiFePO4 battery products. For data on other lithium batteries, you can also refer to it, and I believe it will be very useful to you.
| State of Charge | 12V | 24V | 36V | 48V |
| 100% | ≥13.33V | ≥26.66V | ≥39.99 V | ≥53.32V |
| 75% | 13.3~13.33V | 26.6~26.66V | 39~39.99V | 53.2~53.32V |
| 50% | 13.15~13.3V | 26.3~26.6V | 39.45~39.9V | 52.6~53.2V |
| 25% | 13~13.15V | 26~26.3V | 39~39.45V | 52~52.6V |
| 0% | 10~12V | 20~24V | 30~36V | 40~48V |
Charge and discharge characteristic parameters of lithium batteries
Charging voltage
The upper limit of charging voltage for various lithium batteries varies:
Lithium ion batteries: The upper limit of charging voltage for each cell is generally between 4.2 and 4.3 volts.
LiPo battery: The upper limit of charging voltage is similar to that of lithium-ion batteries, with each cell operating between 4.2 and 4.3 volts.
LiFePO4 battery: The upper limit of charging voltage is relatively low, with each cell charging at approximately 3.6 to 3.8 volts.
Taking the application of lithium-ion batteries and lithium iron phosphate batteries in similar devices as an example, the upper limit of charging voltage for lithium-ion batteries is usually 4.2 volts per cell, while the upper limit of charging voltage for lithium iron phosphate batteries is relatively low, about 3.6 volts per cell.
If the voltage in your area is low or unstable, choosing lithium iron phosphate batteries would be more suitable.
Discharge cut-off voltage
The discharge cut-off voltage of various lithium batteries varies:
Lithium ion batteries and lithium polymer batteries: The discharge cut-off voltage is usually between 2.5 and 3.0 volts.
LiFePO4 battery: The discharge cut-off voltage is relatively high, generally between 2.8 and 3.2 volts.
Taking the application of lithium polymer batteries and lithium iron phosphate batteries in similar equipment as an example, the discharge cut-off voltage of lithium polymer batteries is 2.5 volts per cell, while the discharge cut-off voltage of lithium iron phosphate batteries is even higher, about 2.8 volts per cell.
LiFePO4 battery charging and discharging
Each battery has its own specific charging strategy to maximize battery life. By proper charge and discharge cycle management, it is possible to ensure that the battery operates efficiently for a long time, provides stable and reliable power, and maintains the health and operational efficiency of the battery.
Taking LiFePO4 batteries as an example, the ideal charging method is to fully charge them and then discharge them in a controlled manner to avoid completely emptying the battery.
Mastering the charge and discharge cycle of LiFePO4 batteries is crucial for maintaining their performance and extending their lifespan.
| Characteristics | 12V | 24V | 36V | 48V |
| Charging Voltage | 14.2-14.6V | 28.4V-29.2V | 42.6V~43.8V | 56.8V-58.4V |
| Float Voltage | 13.6V | 27.2V | 40.8V | 54.4V |
| Maximum Voltage | 14.6V | 29.2V | 43.8V | 58.4V |
| Minimum Voltage | 10V | 20V | 30V | 40V |
| Nominal Voltage | 12.8V | 25.6V | 38.4V | 51.2V |
Lithium ion cell voltage related terms: Bulk, Floating and Equalize Voltage
Understanding the relevant terminology of lithium battery voltage would be more helpful for all of this.
LiFePO4 (lithium iron phosphate) batteries are the most popular type of rechargeable lithium-ion batteries, taking it as an example.
It has excellent energy density, long cycle life, and outstanding safety performance.
GycxSolar’s professional engineers test the performance of their LiFePO4 (lithium iron phosphate) battery products by performing constant current charging, constant voltage charging, and balanced charging at different voltage levels to ensure that the battery can be charged correctly and maintain a healthy working state.
The following are specific introductions to the relevant terms of these charging voltage levels:
Bulk Voltage:
During the charging process, the high-capacity charging voltage refers to the highest voltage initially applied. For LiFePO4 batteries, the voltage range is approximately between 3.6 and 3.8 volts per cell.
This voltage level is mainly used for fast charging, with the aim of accelerating the charging process before the battery is charged to 80% to 90% of its capacity.
Floating voltage:
When LiFePO4 batteries are charged to a certain level during constant current charging, the charging voltage will drop to a lower level, which is called floating voltage.
For LiFePO4 batteries, the float charge voltage is usually between 3.3 and 3.4 volts per cell. The purpose of maintaining this voltage is to allow the battery to reach a fully charged state during the charging process while avoiding overcharging.
This helps to extend the battery’s lifespan and prevent damage to the battery.
Equalize Voltage:
Balanced charging is a technique used to adjust the charge balance of each battery in a battery pack. In a multi cell battery system, this process is particularly important as it ensures that each cell receives uniform charging.
The balanced charging voltage of LiFePO4 batteries is usually slightly higher than the standard charging voltage, approximately between 3.8 and 4.0 volts per cell.
A slightly higher voltage helps ensure that each battery in the battery pack can be fully charged, thereby avoiding uneven capacity between batteries.
It should be noted that these voltage levels may vary depending on the product design of the manufacturer and battery designer.
This is also a point worth considering when choosing a brand. Choosing high-quality products from GycxSolar can help you avoid falling into traps.
In addition, adopting appropriate charging technology and controlling stable lithium ion battery voltage levels are crucial for ensuring battery life and performance.
Here is a voltmeter for different charging voltage states for your reference.
| Types | 12V | 24V | 36V | 48V |
| Bulk | 14.6V | 29.2V | 43.8V | 58.4V |
| Float | 13.5V | 27.0V | 40.5V | 54.0V |
| Equalize | 14.4V | 28.8V | 43.2v | 57.6V |
The influence of lithium ion cell voltage
Chemical composition of lithium batteries
Various types of lithium batteries exhibit different voltage characteristics due to their different chemical compositions.
Taking LiFePO4 batteries as an example, their nominal voltage is approximately 3.2 volts per cell, which is usually lower than the nominal voltage of lithium-ion batteries, which typically ranges from 3.6 to 3.7 volts per cell.
Voltage range
Lithium batteries exhibit different voltage levels during different charging stages.
A fully charged lithium battery may achieve a voltage savings of 4.2 volts per charge, while when the battery is discharged to a near empty state, the voltage may drop to 3.0 volts per charge savings.
Temperature influence
Temperature is a key factor affecting the voltage of lithium batteries. When the temperature rises, it may cause an increase in voltage readings; On the contrary, a decrease in temperature may lead to a decrease in voltage output.
Differences between batteries
Even lithium batteries produced in the same batch may have slight differences in voltage output due to slight variations in the manufacturing process.
How does voltage affect battery performance?
The performance of lithium iron phosphate (LiFePO4) batteries is significantly affected by voltage.
Here are several aspects of how voltage affects the performance of LiFePO4 batteries:
Capacity and energy density:
The voltage of LiFePO4 batteries is directly related to their capacity and energy density. The nominal voltage of this type of battery is usually 3.2V, which is lower than other lithium-ion batteries.
Lower voltage may affect its total energy density, but LiFePO4 batteries are known for their stable capacity over a wide range of operating voltages.
Power output capability
The voltage of a battery also determines the level of power it can provide. Batteries with higher voltage can output more power.
LiFePO4 batteries have lower voltage, so it may be necessary to connect more batteries in series to meet the voltage level requirements of certain applications.
Charging characteristics
During the charging process, LiFePO4 batteries exhibit a relatively flat voltage curve, indicating that their voltage can remain relatively constant during charging.
Compared to other lithium-ion batteries, LiFePO4 batteries are easier to control during charging, while other lithium-ion batteries may experience more severe voltage fluctuations during charging.
Safety and stability
The voltage characteristics of batteries play a decisive role in their safety and stability.
LiFePO4 batteries are praised for their excellent thermal and chemical stability. A lower operating voltage helps to improve overall safety and reduce the risk of thermal runaway.
Overall, voltage affects the capacity, energy density, power output, charging characteristics, and safety of batteries.
A deep understanding of the impact of voltage on batteries is crucial for designing and optimizing the application systems of these batteries.
Equipment compatibility of lithium battery voltage
Ensuring that the power supply voltage matches the equipment requirements is crucial for ensuring the normal operation and safety of the equipment.
Consumer electronic devices
Devices such as smartphones and laptops need to operate within a certain voltage range, and using mismatched chargers may cause damage to the equipment.
Industrial and commercial applications such as automobiles
Electric and hybrid vehicles rely on battery systems with specific voltage compatibility to ensure their safe and efficient operation. Voltage deviation from the recommended range may affect the performance and safety of the vehicle.
Industrial machinery also has strict requirements for voltage. For example, CNC machine tools or robots typically need to operate within precise voltage parameter ranges to ensure stable and accurate functionality.
Medical equipment
Medical devices, such as MRI machines and pacemakers, require precise and stable voltage supply to ensure patient safety and device reliability.
Renewable energy system
Solar panels require the use of voltage converters to adjust their changing output voltage to meet the voltage requirements of the power grid or energy storage system.
How to measure lithium ion cell voltage？
Measuring battery voltage usually requires the use of a voltmeter, which is an instrument specifically designed to measure the potential difference between two points in a circuit.
The following are the general steps for measuring battery voltage:
Choose a suitable voltmeter: Ensure that its measurement range covers the possible voltage values of the battery.
Disconnect the circuit: If the battery is part of a larger circuit, the circuit should be disconnected before measuring the voltage to avoid danger and ensure accurate readings.
Correctly connect the voltmeter: Connect the voltmeter to the positive and negative terminals of the battery. Generally, the red probe is connected to the positive electrode and the black probe is connected to the negative electrode.
Read voltage: After connecting the voltmeter, it will display the current battery voltage. If the voltmeter has multiple ranges, make sure to select the range that matches the battery voltage.
Interpretation of Reading: The voltmeter will display voltage in volts (V) and record this reading to understand the voltage level of the battery.
It should be noted that the voltage of the battery may vary depending on the charging state (fully charged, partially charged, or discharged).
Therefore, when interpreting lithium battery voltage readings, it is crucial to consider the battery’s charging status.
Conclusion
Mastering the voltage characteristics of lithium batteries is crucial for their efficient use in various applications.
By reading this article, you can make wise charging, discharging, and battery management decisions to maximize the performance and lifespan of these advanced energy solutions.
For more information about lithium battery voltage and related products, please consult GycxSolar, a well-known service provider and industry expert.
Our top tier college graduation experts are dedicated to serving you, ensuring that you can successfully integrate these efficient energy solutions into your project.
Frequently asked questions
Are all lithium batteries 3.7 volts?
Not all lithium batteries have a voltage of 3.7 volts. The voltage level of lithium batteries depends on their chemical composition and battery configuration.
For example, the nominal voltage of lithium-ion batteries is usually between 3.2 volts and 3.7 volts. The nominal voltage of lithium iron phosphate (LiFePO4) batteries is usually around 3.2 volts.
What is the cut-off voltage of a 12V lithium-ion battery?
The discharge cut-off voltage of a 12V lithium-ion battery is determined by the number of battery cells connected in series.
Usually, each battery is between approximately 2.5 and 3.0 volts.
For a 12V lithium-ion battery pack consisting of 4 batteries connected in series, this means that the discharge cut-off point of the total voltage will be the sum of the cut-off voltages of these individual batteries.
Therefore, the discharge cut-off voltage of the entire battery pack may be between 10 volts and 12 volts.
How to determine if my LiFePO4 battery is malfunctioning?
Here are some signals that may indicate a problem with the battery:
The charging time of the battery is abnormally long, or it cannot be charged at all.
The device frequently shuts down on its own when the battery level is displayed as sufficient.
After prolonged use, the battery may experience expansion, which may indicate that the battery is damaged or faulty.
What is the critical voltage threshold for LiFePO4 batteries?
Taking a 12V LiFePO4 battery as an example, its critical voltage threshold is about 10V.
During the discharge process, if the voltage drops below this level, it may cause irreversible damage to the battery.
What should be reading of a ithium ion cell voltage？
Battery manufacturers will label the lithium batteries they produce higher.
Some lithium-ion batteries may have a higher nominal voltage because their lithium chemicals are different, allowing the battery to have a higher voltage.
