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The Comprehensive Guide to LiFePO4 Voltage Chart

David Lee
David Lee
—
07/05/2024

Are you considering LiFePO4 lithium batteries for your next project or application? Understanding the voltage characteristics of these batteries is crucial for their optimal performance and longevity. In this comprehensive guide, we'll delve into the specifics of LiFePO4 lithium battery voltage, providing you with a clear understanding of how to interpret and utilize a LiFePO4 lithium battery voltage chart.


Part 1: Understanding LiFePO4 Lithium Battery Voltage

Lithium Iron Phosphate (LiFePO4) batteries are recognized for their high safety standards, excellent temperature resistance, fast discharge rates, and long lifespan. These high-capacity batteries effectively store energy and power a variety of devices across different environments. The voltage of LiFePO4 rechargeable batteries varies based on the State of Charge (SOC); as the battery charges or discharges, the voltage changes. Higher voltage in a LiFePO4 battery indicates greater capacity and energy storage.

To better understand LiFePO4 battery voltage, here are some key definitions:

  • Nominal Voltage: The optimal performance level of the battery is around 3.25V. This is the standard for monitoring charging and discharging.
  • Storage Voltage: This is the ideal voltage for storing the battery when not in use for an extended period. Maintaining this voltage helps preserve battery health and minimizes capacity loss.
  • Fully Charged Voltage: This voltage reaches up to 3.65V, which is the maximum safe charging level. Overcharging beyond this point can cause irreversible damage to the battery.
  • Discharge Voltage: The optimal discharge voltage is 2.5V. Users should avoid discharging below this level, as doing so can harm the battery.
  • Deep Discharge: When the voltage falls below the recommended threshold, the battery may enter a state of deep discharge, which can lead to permanent damage or render the LiFePO4 battery unusable.

Part 2: LiFePO4 Voltage Chart: 3.2V, 12V, 24V, 36V & 48V

The LiFePO4 Voltage Chart stands as an essential resource for comprehending the charging levels and condition of Lithium Iron Phosphate batteries.

This visual aid showcases the voltage spectrum from full charge to complete discharge, enabling users to determine the present charge status of their batteries.

It acts as a convenient guide for assessing performance, promoting efficient utilization, and prolonging the lifespan of these reliable and efficient energy storage solutions.

This chart represents a vital tool for the utilization of LiTime's array of LiFePO4-powered products.

State of Charge 12V 24V 36V 48V
100% ≥13.33V ≥26.66V ≥39.99V ≥53.32V
75% 13.3~13.33V 26.6~26.66V 39.9~39.99V 53.2~53.32V
50% 13.15~13.2V 26.3~26.4V 39.45~39.6V 52.6~52.8V
25% 13~13.15V 26~26.3V 39~39.45V 52~52.6V
0% 10~12V 20~24V 30~36V 40~48V

 

Related reading: 48V VS 51.2V Golf Cart Battery, What are The Differences

3.2V LiFePO4 Cell Voltage Chart

Individual LiFePO4 (lithium iron phosphate) cells generally have a nominal voltage of 3.2V. These cells reach full charge at 3.65V and are considered fully discharged at 2.5V.

Understanding the voltage levels is crucial for monitoring battery health and performance.

3.2v lifepo4 battery voltage chart

12V Lithium Battery Voltage Charge

12V LiFePO4 batteries are an excellent upgrade from traditional 12V lead-acid batteries, offering enhanced safety and performance for off-grid solar systems. These lithium iron phosphate batteries provide a more reliable power source, with a longer lifespan and faster charging capabilities.

When fully charged, a 12V LiFePO4 battery reaches a voltage of 14.6V. As the battery discharges, the voltage gradually decreases, reaching 10V when fully discharged. It’s crucial to monitor these voltage levels to ensure optimal performance and longevity of the battery.

12v lifepo4 battery voltage chart

Monitoring the voltage of your 12V LiFePO4 battery is essential to maintaining its health and performance. Avoiding deep discharges (below 10V) and regularly charging to full capacity (14.6V) will help extend the battery’s lifespan and ensure reliable power for your off-grid solar system.

24V LiFePO4 Lithium Battery Voltage Charge

When considering a power solution, you have the option to purchase a 24V LiFePO4 battery or connect two identical 12V LiFePO4 batteries in series. This flexibility allows you to tailor your energy storage system to fit your specific needs, whether for off-grid applications, solar power systems, or electric vehicles.

24v lifepo4 battery voltage chart

A fully charged 24V LiFePO4 battery reaches a voltage of 29.2V. As the battery discharges, the voltage gradually decreases, reaching 20V when fully discharged. Monitoring these voltage levels is crucial for maintaining optimal battery health and ensuring long-term performance.

36V LiFePO4 Lithium Battery Voltage Charge

36V LiFePO4 batteries offer a robust option for various applications, including big trust trolling motor, solar power systems, golf cart and other renewable energy setups. You can either opt for a single 36V LiFePO4 battery or connect three 12V LiFePO4 batteries in series to achieve the desired voltage.

A fully charged 36V LiFePO4 battery reaches a voltage of 43.2V, while it typically discharges to 30V when depleted. Understanding the voltage levels throughout the charging and discharging process is essential for maximizing the performance and lifespan of your battery.

36v lifepo4 battery voltage chart

48V LiFePO4 Lithium Battery Voltage Charge

48V batteries are commonly utilized in larger solar power systems and other high-demand applications. One of the key advantages of using a 48V system is that it allows for lower amperage, which can significantly reduce equipment and wiring costs. This efficiency makes 48V configurations particularly appealing for both residential and commercial solar installations, electric vehicles, and energy storage solutions.

When fully charged, a 48V LiFePO4 battery reaches a voltage of 54.6V. During discharge, the voltage typically drops to 40V when fully depleted. Understanding the voltage levels throughout the charging and discharging cycles is essential for optimizing battery performance and ensuring a long service life.

48v lifepo4 battery voltage chart

Part 3: LiFePO4 Battery Charging & Discharging

Comprehending the charging and discharging processes of LiFePO4 batteries, also known as cycles, is vital for preserving their longevity and effectiveness.

All batteries necessitate specific charging patterns to optimize their lifespan. For LFP battery cycles, a consistent charge up to their full capacity and a controlled discharge that avoids complete depletion is ideal. If you have a battery pack rated at 100Ah and 60Ah of charge remaining, the State of Charge (SoC) would be 60%.

Proper management of battery cycles ensures that the battery functions optimally over time, delivering dependable power while safeguarding its health and operational capacity.

But how do charging and discharging work for LiFePO4 batteries? Here’s a detailed breakdown.

3.1 Charging LiFePO4 Batteries:

LiFePO4 batteries typically charge within a voltage range of 3.2V to 3.65V per cell, which means for a 12V (4-cell) battery, the full charge voltage is around 14.6V.

Here's a charging voltage recommend for lithium batteries:

lifepo4 battery charging voltage chart 

A. Charging Process: CC/CV

LiFePO4 (Lithium Iron Phosphate) batteries are a type of rechargeable lithium-ion battery known for their high energy density, long cycle life, and enhanced safety features. LiFePO4 batteries follow a CC/CV (Constant Current/Constant Voltage) charging process.

lifepo4 lithium battery charging logic cc/cv

1) Constant Current (CC) Phase:

  • During this phase, the charger delivers a constant current to the battery. The voltage gradually increases as the battery charges, but the current remains fixed at a certain rate (often set by the charger).
  • The bulk charge happens here, bringing the battery to about 80-90% of its capacity. For example, for a 12V LiFePO4 battery, the voltage may rise up to around 14.2V or 14.4V.
  • This phase is fast and represents the primary charging period.

2) Constant Voltage (CV) Phase:

  • Once the battery reaches its target voltage (typically 3.65V per cell or around 14.6V for a 12V battery), the charger switches to the constant voltage phase.
  • In this phase, the charger maintains a constant voltage while the current begins to taper off. The battery absorbs the remaining 10-20% of its capacity until the current drops to a very low level.
  • This phase prevents overcharging and brings the battery to full charge safely.

3) Termination (End of Charge):

  • LiFePO4 batteries don’t require a float charge. Once the current drops to a very low value (typically below 0.05C or 5% of the battery’s capacity), the charger should stop to avoid overcharging. The charger either shuts off or goes into a low-power state.

It's important to note that these voltage levels can vary based on the specific manufacturer's recommendations and the design of the battery management system being used. Additionally, proper charging techniques and voltage levels are critical to ensuring the longevity and performance of LiFePO4 batteries.

B. Optimal Charging Conditions

  • Temperature: Ideal charging occurs between 0℃ to 50℃ / 32℉ to 122℉. Charging below 0°C (32°F) can damage the battery. It's recommended to use the battery with low-temperature chariging off protection like LiTime cold weather series if you are living in the area where winter is long.
  • Current Limitations: Ensure the charger is designed for LiFePO4, which typically has a lower charging current to prevent heat buildup.

3.2 Discharging LiFePO4 Batteries:

A. Discharge Voltage Range:

LiFePO4 batteries can safely discharge down to 2.5V per cell, but most BMS systems will cut off at around 2.8V to 3.0V per cell to protect the battery. For a 12V battery, this is about 10V to 11V.

B. Depth of Discharge (DoD):

LiFePO4 batteries can be discharged up to 100% of their capacity without significantly reducing their lifespan. They support deep discharge without damage.

C. Temperature Range for Discharge:

The discharge temperature range is broader than the charging range, typically from -20°C to 60°C (-4°F to 140°F).

D. Discharge Rate:

These batteries have high discharge rates compared to lead-acid. LiFePO4 can safely discharge at high current, making them suitable for applications that require rapid power draw, such as electric motors.

E. Battery Management System (BMS):

LiFePO4 batteries usually come with an integrated BMS to monitor overcharging, over-discharging, overheating, and short circuits, ensuring safe operation.

information of battery management system protection

Part 4: How Does Voltage Affect LiFePO4 Battery Performance?

Voltage plays a crucial role in the performance, efficiency, and longevity of lithium iron phosphate (LiFePO4) batteries. Understanding how voltage impacts these factors is essential for optimal utilization and maintenance.

1. Capacity: The voltage of a LiFePO4 battery directly affects its capacity. As the voltage increases, so does the capacity, allowing the battery to store more energy and power your devices for longer periods. Higher voltage batteries are capable of handling larger energy demands.

2. Power Output: Voltage also influences the power output of the battery. Higher voltage batteries can deliver more power, which is important for applications that require high power output, such as electric vehicles and power tools. However, LiFePO4 batteries have lower voltage compared to other lithium-ion chemistries, so they may require more cells in series to achieve the desired voltage levels for certain applications.

3. Charging & Discharging: The voltage of a LiFePO4 battery influences its charging process. Charging the battery within the correct voltage range ensures safety and efficiency. Using an incorrect voltage can lead to overheating or undercharging, both of which negatively impact battery health, performance, and overall lifespan. Discharging below the recommended voltage level can cause permanent damage to the battery and reduce its lifespan. It’s important to avoid deep discharges to maintain optimal performance.

4. Safety and Stability: The voltage of a LiFePO4 battery contributes to its safety and stability. LiFePO4 batteries are known for their excellent thermal and chemical stability, and their lower operating voltage contributes to their overall safety. The lower voltage reduces the risk of thermal runaway and other safety issues associated with higher voltage lithium-ion chemistries.

All in all, voltage plays a critical role in determining the performance characteristics of LiFePO4 batteries, impacting their capacity, energy density, power output, charging characteristics, and safety. Understanding how voltage affects LiFePO4 batteries is important for designing and optimizing systems that use these batteries, such as electric vehicles, renewable energy storage systems, and portable electronics.

Part 5: How to Measure Battery Voltage

1. Utilizing a Votimeter

Measuring battery voltage typically involves using a voltmeter or a multimeter, a device specifically designed to determine the electrical potential difference between two points in an electrical circuit. Here's a general guide on how to measure battery voltage:

  • Select the Appropriate Voltmeter: Ensure that the voltmeter you use is capable of measuring the battery's voltage. It should have a voltage range that encompasses the expected voltage of the battery.
  • Turn Off the Circuit: If the battery is part of a larger circuit, switch off the circuit before measuring the battery voltage. This action helps prevent potential electrical hazards and ensures accurate measurements.
  • Connect the Voltmeter: Attach the voltmeter to the battery terminals. Typically, the red lead of the voltmeter connects to the positive terminal of the battery, while the black lead connects to the negative terminal.
  • Read the Voltage: Once the voltmeter is correctly connected, it will display the battery's voltage. If the voltmeter offers multiple voltage ranges, make sure it is set to an appropriate range for the expected battery voltage.
  • Interpret the Reading: The voltmeter will show the voltage in volts (V). Take note of the displayed reading to determine the battery's voltage.

Check Battery Voltage Using a Multimeter

It's important to note that when measuring battery voltage, especially in the case of rechargeable batteries, the voltage may vary based on whether the battery is fully charged, partially charged, or discharged. Therefore, it's crucial to consider the battery's state of charge when interpreting the voltage reading.

Furthermore, always adhere to safety precautions when working with batteries and electrical circuits to prevent injury or equipment damage.

Related readiing: How to Test a Battery Using a Multimeter

2. Measuring Battery Voltage with a Battery Monitor

A battery monitor is a device permanently installed in your system to provide real-time data about your battery’s performance, including voltage, current, and charge status.


3. Measuring Battery Voltage via Bluetooth with a Smartphone

Many modern LiFePO4 batteries come with built-in Bluetooth functionality. This allows you to monitor the battery’s voltage and other data wirelessly via a smartphone app.


FAQs for LiFePO4 Voltage Chart

1. What is the minimum voltage for LiFePO4 that can cause damage?

For 12V LiFePO4 batteries, the minimum voltage that can cause damage is approximately 10V. If the battery is discharged below this threshold, it is likely to suffer permanent damage. Therefore, it is crucial to consult the LiFePO4 battery voltage chart and ensure that you charge your batteries safely.

2. What is the low voltage cutoff for LiFePO4?

The low voltage cutoff for LiFePO4 is the predetermined voltage threshold below which the battery should not discharge. For LiFePO4 batteries, this value is approximately 2.5V per cell.

3. What voltage should LiFePO4 bulk absorb?

The recommended bulk/absorb voltage for LiFePO4 ranges between 14.2 and 14.6 volts. It is also possible to use a voltage of 14.0 volts with an extended absorb time. Additionally, slightly higher voltages of around 14.8-15.0 volts are acceptable before disconnecting the battery.

4. How can I determine if my LiFePO4 battery is malfunctioning?

While no battery can last indefinitely, signs of degradation may appear after a few years with a LiFePO4 battery. Here are a few indicators of potential issues:

  • The 12V LiFePO4 battery takes longer than usual to charge or fails to charge at all.
  • Electronic devices unexpectedly power off, even when the battery has ample charge remaining.
  • After a few years, the LiFePO4 battery may become overinflated, indicating potential damage or a faulty battery.

5. Can a Battery Have Good Voltage but Still Be Bad?

Yes, a battery can show good voltage and still be considered faulty. Voltage is only one indicator of a battery’s health, and it doesn’t give the full picture.

A battery’s capacity—its ability to store and supply energy—can decline over time due to factors like age, usage, and environmental conditions. This means that even though the battery may display good voltage when tested, it might not sustain that voltage under load for long enough to be functional.

Moreover, as a battery deteriorates, its internal resistance can increase. This leads to a significant voltage drop when the battery is under load, reducing power output and performance, despite showing acceptable voltage in an open-circuit state.

Therefore, while voltage is important, it is not the only factor to evaluate a battery’s condition. Other aspects like capacity, internal resistance, and performance under load are critical in determining the overall health of a battery.

6. How Can a Battery Have Voltage but No Current?

A battery can have voltage but no current when it’s not connected to a circuit. Voltage measures the electric potential difference between two points (measured in volts), representing the "push" that drives electric charges. However, current (measured in amps) is the actual flow of those charges, and it only occurs when a complete circuit exists.

Without a closed circuit—meaning the battery’s positive and negative terminals aren’t connected through a conductor—no current flows. The battery still holds voltage across its terminals, but current won’t flow until a circuit is completed by connecting the terminals with a conductor (e.g., a wire). Once the circuit is closed, current will begin to flow from the battery through the circuit.

Conclusion

Understanding the voltage characteristics of LiFePO4 lithium batteries is essential for their effective utilization in a wide range of applications. By referencing a LiFePO4 lithium battery voltage chart, you can make informed decisions regarding charging, discharging, and overall battery management, ultimately maximizing the performance and lifespan of these advanced energy storage solutions.

For more information on LiFePO4 lithium batteries and their voltage characteristics, consult with reputable manufacturers like LiTime and industry experts to ensure the successful integration of these advanced energy storage solutions into your projects.

David Lee
David Lee
David Lee is a renewable energy consultant with global experience in off-grid systems and battery applications, especially in golf carts. A graduate of the University of Sydney, he shares insights on sustainability through his writing.

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