LiFePO4 Voltage Chart

LiFePO4 Voltage Chart: A Comprehensive Guide

by WilliamZachary on Apr 13 2024
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    Overview of LiFePO4 Battery Voltage

    Lithium Iron Phosphate (LiFePO4) batteries are favored in the fields of electric bicycles, electric vehicles, forklifts, marine applications, AGVs, and floor sweepers due to their high energy density, long cycle life, and high safety. Lifepo4 batteries have become the preferred choice for high-performance applications due to their excellent performance. They offer stable voltage, consistent power output, and a wide operating temperature range. This article focuses on the voltage chart of Lifepo4 batteries and Lifepo4 vs. NMC (Nickel Manganese Cobalt).

    What is a LiFePO4 Voltage Chart?

    A LiFePO4 battery voltage chart typically shows the discharge curve specific to LiFePO4 batteries. The voltage varies according to the capacity from 100% to 0%.

    SOC 1 Cell 12V 24V 36V 48V
    100% 3.65V 14.6V 29.2V 43.8V 58.4V
    100% Rest 3.4V 13.6V 27.2V 40.8V 54.4V
    90% 3.35V 13.4V 26.8V 40.2V 53.6V
    80% 3.32V 13.28V 26.56V 39.84V 53.12V
    70% 3.3V 13.2V 26.4V 39.6V 52.8V
    60% 3.27V 13.08V 26.16V 39.24V 52.32V
    50% 3.26V 13.04V 26.08V 40.2V 39.12V
    40% 3.25V 13V 26V 39V 52V
    30% 3.22V 12.88V 25.76V 38.64V 51.52V
    20% 3.2V 12.8V 25.6V 38.4V 51.2V
    10% 3V 12V 24V 36V 48V
    0% 2.5V 10V 20V 30V 40V

    LiFePO4 Battery Discharge Cutoff Voltage: 2.5V

    LiFePO4 Battery Float Charge Voltage: 3.2V

    LiFePO4 Battery Nominal Voltage: 3.2V

    3.2V LiFePO4 Cell Charging and Discharging Voltage Chart

    3.2V LiFePO4 cell voltage chart

    12V LiFePO4 Pack Charging and Discharging Voltage Chart

    12V 100Ah LiFePO4 batteries provide a significant upgrade over traditional 12V lead acid batteries. They are highly regarded as one of the safest options for off-grid solar systems. When fully charged, the battery voltage reaches 14.6V, while it drops to 10V when fully discharged. The following voltage chart illustrates the voltage decline in relation to the battery's capacity for a 12V LiFePO4 battery:

    Capacity Battery Voltage
    100% 14.6V
    90% 13.4V
    80% 13.28V
    70% 13.2V
    60% 13.08V
    50% 13.04V
    40% 13V
    30% 12.88V
    20% 12.8V
    10% 12V
    0% 10V
    12V LiFePO4 cell voltage chart

    LiFePO4 Battery Discharge Cutoff Voltage: 10V
    LiFePO4 Battery Float Charge Voltage: 13.6V
    LiFePO4 Battery Nominal Voltage: 12.8V

    24V LiFePO4 Pack Charging and Discharging Voltage Chart

    You have two options: you can either purchase a 24V LiFePO4 battery or acquire two identical 12V LiFePO4 batteries and connect them in series. When fully charged, these batteries reach a voltage of 29.2V and drop to 20V during discharge.
    Capacity Battery Voltage
    100% 29.2V
    90% 26.8V
    80% 26.56V
    70% 26.4V
    60% 26.16V
    50% 26.08V
    40% 26V
    30% 25.76V
    20% 25.6V
    10% 24V
    0% 20V

    24V LiFePO4 cell voltage chart

    LiFePO4 cell Discharge Cutoff Voltage: 20V
    LiFePO4 cell Float Charge Voltage: 27.2V
    LiFePO4 cell Nominal Voltage: 25.6V

    36V LiFePO4 Pack Charging and Discharging Voltage Chart

    You can either purchase a 36V LiFePO4 battery or acquire three identical 12V LiFePO4 batteries and connect them in series. When fully charged, these batteries reach a voltage of 43.8V and drop to 30V during discharge.

    Capacity Battery Voltage
    100% 43.8V
    90% 40.2V
    80% 39.84V
    70% 39.6V
    60% 38.24V
    50% 39.12V
    40% 39V
    30% 38.64V
    20% 38.4V
    10% 36V
    0% 30V
    24V LiFePO4 cell voltage chart
    LiFePO4 Battery Discharge Cutoff Voltage: 30V
    LiFePO4 Battery Float Charge Voltage: 43.8V
    LiFePO4 Battery Nominal Voltage: 38.4V

     

    48V LiFePO4 Pack Charging and Discharging Voltage Chart

    In larger solar power systems, 48V batteries are commonly utilized. These high-voltage solar systems effectively keep the amperage low, resulting in significant savings on equipment and wiring expenses.

    Capacity Battery Voltage
    100% 58.4V
    90% 53.6V
    80% 53.12V
    70% 52.8V
    60% 52.32V
    50% 52.16V
    40% 52V
    30% 51.52V
    20% 51.2V
    10% 48V
    0% 40V
    48V LiFePO4 cell voltage chart

    LiFePO4 Battery Discharge Cutoff Voltage: 40V
    LiFePO4 Battery Float Charge Voltage: 54.4V
    LiFePO4 Battery Nominal Voltage: 51.2V

    What is the relationship between the state of charge (SOC) and the voltage of the SOC?

    The relationship between State of Charge (SoC) and voltage for LiFePO4 batteries is as follows:

    SoC (State of Charge) represents the charging level of a battery relative to its capacity. SoC is typically expressed as a percentage, where 0% represents empty or discharged, and 100% represents full or charged. Another related measurement is Depth of Discharge (DoD), which is calculated as 100 - SoC (100% represents full, 0% represents empty). SoC is commonly used when discussing the current state of the battery during use, while DoD is often used when discussing the battery's lifespan after repeated cycles.

    Due to the non-linear relationship between SoC and voltage, the battery management system (BMS) intervenes to prevent over-discharge when the battery reaches a low SoC (close to 0%). Similarly, the charging process slows down as the battery approaches a high SoC (close to 100%) to protect the battery.

    The table below shows the voltage range for LiFePO4 cell:

    SOC (State Of Charge) Voltage (V)
    100% 3.60-3.65V
    90% 3.50-3.55V
    80% 3.45-3.50V
    70% 3.40-3.45V
    60% 3.35-3.40V
    50% 3.30-3.35V
    40% 3.25-3.30V
    30% 3.20-3.25V
    20% 3.10-3.20V
    10% 2.90-3.00V
    0% 2.00-2.50V

    Charge State Curve

    Voltage: The higher the nominal voltage of the battery, the more fully charged the battery is. For example, a Lifepo4 battery with a nominal voltage of 3.2V reaches a voltage of 3.65V, indicating that the battery has been greatly maximized.

    Coulomb Meter: Measures the current flowing into and out of the battery using Ampere Seconds (As) to determine the charging and discharging rate.

    Specific Gravity: Requires a hydrometer to measure the State of Charge (SoC). It works by monitoring the density of the liquid based on buoyancy.

    Charge State Curve

    Lithium iron phosphate battery charging parameters

    Here are the charging parameters for LiFePO4 batteries, including different voltage types such as charging voltage, float voltage, maximum voltage/minimum voltage, and nominal voltage. The table below provides the charging parameters for LiFePO4 batteries with voltages of 3.2V, 12V, 24V, 36V, and 48V.

    Charging Parameters 3.2V 12V 24V 36V 48V
    Charging Voltage 3.5~3.65V 14.2~14.6V 28.4~29.2V 42.6~43.8V 56.8~58.4V
    Float Voltage 3.2V 13.6V 27.2V 43.8V 54.4V
    Maximum Voltage 3.65V 14.6V 29.2V 43.8V 58.4V
    Minimum Voltage 2.5V 10V 20V 30V 40V
    Nominal Voltage 3.2V 12V/12.8V 24V/25.6V 363V/38.4V 48V/51.2V

    Discharge Curve of LiFePO4 Battery

    Discharge refers to the process of extracting electrical energy from a battery to power electronic devices. A discharge curve of a battery typically represents the relationship between voltage and discharge time. The graph below shows the discharge curves of a 12V LiFePO4 battery at different discharge rates.

    Discharge Curve of LiFePO4 Battery

    Factors Influencing Battery State of Charge (SoC)

    The factors influencing the state of charge (SoC) of a battery can be categorized into temperature, materials, application, and maintenance.

    • Battery Temperature: If the battery operates at excessively high or low temperatures, it can reduce the charging efficiency and affect the SoC.
    • Battery Materials: Different battery chemistries utilize different materials, which can impact the SoC.
    • Battery Application: Various application scenarios or purposes can also influence the SoC.
    • Battery Maintenance: Improper battery maintenance can adversely affect the battery's lifespan and SoC.

    What is the capacity range of lithium iron phosphate batteries?

    The capacity range of LiFePO4 batteries varies depending on the specific model and manufacturer. Common capacities for LiFePO4 batteries include 4Ah, 10Ah, 20Ah, 50Ah, 100Ah, 150Ah, and so on. Increasing the number of LiFePO4 batteries connected in parallel will result in higher overall capacity. Additionally, increasing the number of LiFePO4 batteries connected in series will increase the overall voltage of the battery pack.

    Comparison of Parameters between LiFePO4 and Lithium-ion (Li-ion) Batteries

    Parameter NMC (Nickel Manganese Cobalt) LFP (Lithium Iron Phosphate)
    Nominal Voltage 3.6V 3.2V
    Charging Voltage 4.2V 3.5~3.65V
    Minimum Voltage 2.5V 2.5V
    Maximum Voltage 4.2V 3.65V
    Battery Capacity (mAh/g) ~195 ~145
    Energy Density (Wh/kg) ~240 ~170
    Cycle Life 3000 8000
    Thermal Stability & Safety 150-200°C 300°C
    Parameter LiFePO4 (Lithium Iron Phosphate) Li-ion (Lithium-ion)
    Nominal Voltage Typically 3.2V per cell Typically 3.6V to 3.7V per cell
    Energy Density Lower compared to Li-ion batteries Higher compared to LiFePO4 batteries
    Cycle Life Longer cycle life, typically exceeding 8000 cycles Relatively shorter cycle life, typically around 500-1000 cycles
    Safety Considered safer and more stable Requires additional safety measures
    Temperature Performance Better performance at extreme temperatures Sensitive to high temperatures
    Cost Generally higher cost Relatively lower cost
    Applications Electric vehicles, renewable energy storage, medical devices Portable electronic devices, electric tools, consumer electronics

    Visual Energy Structure and Working Principle of LiFePO4 Battery

    Structure

    On the right side, LiFePO4 serves as the positive electrode of the battery, connected to the battery's positive terminal via aluminum foil. In the middle, a polymer separator separates the positive and negative electrodes, allowing lithium ions (Li+) to pass through while preventing the passage of electrons (e-). On the left side, the negative electrode of the battery is composed of carbon (graphite) and is connected to the battery's negative terminal through copper.

    LiFePO4 Structure

    Working Principle

    During charging:

    1. LiFePO4 undergoes an oxidation reaction, releasing lithium ions (Li+) and electrons (e-).
    2. Lithium ions (Li+) move through the electrolyte and separator, reaching the negative electrode.
    3. At the negative electrode, the lithium ions (Li+) are stored in the carbon (graphite) structure.

    During discharging:

    1. The stored lithium ions (Li+) at the negative electrode move back through the electrolyte and separator towards the positive electrode.
    2. At the positive electrode, the lithium ions (Li+) react with the LiFePO4, causing a reduction reaction and releasing electrons (e-).
    3. The released electrons (e-) flow through the external circuit, generating electrical energy to power devices.
    4. The lithium ions (Li+) and electrons (e-) continue to cycle back and forth as the battery charges and discharges.

    How to Measure the Capacity of a LiFePO4 Battery

    Ensure it is fully charged: Use a charger compatible with the battery and charge it to full capacity.

    Use specialized equipment: Utilize a dedicated battery tester (multimeter) for accurate readings and to determine the actual capacity of the battery.

    Perform a discharge test: Connect the battery to a constant load that falls within the safe operating range of the battery. Record the discharge time to ensure the battery fully discharges within the desired timeframe (reaching the minimum voltage).

    Calculate the capacity: Use the following formula to calculate the battery capacity: Capacity (Ah) = Discharge Current (A) x Discharge Time (hours).

    For example, if the battery discharges at 5 Amperes for 1 hour, the capacity would be 5 Ah.

    Cycle Life and Factors Affecting LiFePO4 Battery

    Charge and Discharge

    The battery should not be overcharged or over-discharged. It is essential to promptly connect and disconnect the charger. Overcharging and over-discharging can impact the cycle life of the battery.

    LiFePO4 Battery Charge and Discharge

    Discharge Depth

    The deeper the discharge, the greater the impact on the battery's lifespan. Therefore, it is advisable to avoid deep discharges and scientifically extend the lifespan of the LiFePO4 battery.

    Working Environment

    Ensure that the LiFePO4 battery is not used in high-temperature or low-temperature environments to avoid affecting the internal battery activity. If using the battery at lower temperatures, then a heated LiFePO4 battery would be the optimal choice.

    How to Increase The LiFePO4 Battery Lifespan?

    To increase the lifespan of a LiFePO4 battery, consider the following tips:

    1. Optimal Temperature: LiFePO4 batteries perform best within a moderate temperature range. Avoid exposing them to extreme temperatures, both high and low, as it can negatively impact battery performance and reduce lifespan. Store and use the battery in a temperature-controlled environment.
    2. Proper Charging: Charge the LiFePO4 battery using a charger specifically designed for LiFePO4 chemistry. Follow the manufacturer's recommendations for charging voltage and current limits. Avoid charging the battery too quickly or at high currents, as it can generate excess heat and potentially damage the battery.
    3. Avoid Over-Discharging: LiFePO4 batteries should not be fully discharged or deeply discharged regularly. Over-discharging can lead to irreversible damage and significantly reduce the battery's lifespan. Keep the Depth of Discharge (DoD) below 80% whenever possible.
    4. Regular Maintenance: Implement a regular maintenance routine for your LiFePO4 battery. This includes checking the battery's voltage periodically, ensuring proper connections, and cleaning the terminals if necessary. Proper maintenance can help identify any issues early and ensure optimal performance.
    5. Balanced Charging: If using LiFePO4 batteries in a multi-cell configuration, employ a balanced charging system. This ensures that each cell in the battery pack is charged and discharged evenly, preventing cell imbalances that can lead to reduced capacity and lifespan.
    6. Avoid Physical Damage: Handle LiFePO4 batteries with care and avoid subjecting them to physical damage. Protect the battery from impacts, vibrations, and excessive mechanical stress. Damaged cells or packs can compromise safety and reduce longevity.
    Voltage (V) Capacity (Ah %) Charge Cycles (If charged and discharged to each of these voltages every day)

    Lifespan (Above 80% Original Capacity)

    (Charged once a day)

    14.4V 100% 3200 cycles 9 years
    13.6V 100% 3200 cycles 9 years
    13.4V 99% 3200 cycles 9 years
    13.3V 90% 4500 cycles 12.5 years
    13.2V 70% 8000 cycles 20 years
    13.1V 40% 8000 cycles 20 years
    13.0V 30% 8000 cycles 20 years
    12.9V 20% 8000 cycles 20 years
    12.8V 17% 6000 cycles 16.5 years
    12.5V 14% 4500 cycles 12.5 years
    12.0V 9% 4500 cycles 12.5 years
    10.0V 0% 3200 cycles 9 years

    What voltage indicates a lithium battery is at 50% capacity?

    Lithium Battery Voltage Chart
    Capacity (%) Lead Battery Lithium Battery Lithium AV-Battery
    100% 12.70V 13.60V 12.60V
    90% 12.50V 13.32V 12.10V
    80% 12.42V 13.28V 11.60V
    70% 12.32V 13.20V 11.35V
    60% 12.20V 13.16V 11.10V
    50% 12.06V 13.13V 10.80V
    40% 11.90V 13.10V 10.70V
    30% 11.75V 13.00V 10.60V
    20% 11.58V 12.90V 10.45V
    10% 11.31V 12.00V 10.25V
    0% 10.50V 10.00V 9.00V

     

    What is the typical voltage of a lithium-ion battery?

    Lithium-ion batteries have a nominal cell voltage of around 3.60V. Some are marked as high as 3.70V per cell, with special types achieving up to 3.85V, using enhanced internal components.

    Nominal Cell Voltage Typical End-of-Discharge Max Charge Voltage Notes
    3.6V 2.8–3.0V 4.2V Classic nominal voltage of cobalt-based lithium-ion battery.
    3.7V 2.8–3.0V 4.2V Marketing advantage. Achieved by low internal resistance.
    3.8V 2.8–3.0V 4.35V Surface coating and electrolyte additives. The charger should have the correct full-charge voltage for additional capacity.
    3.85V 2.8–3.0V 4.4V Surface coating and electrolyte additives. The charger should have the correct full-charge voltage for additional capacity.

     

    Conclusion

    The LiFePO4 Voltage Chart provides a comprehensive guide to understanding the voltage characteristics of LiFePO4 batteries and their corresponding capacities, charge cycles, and expected lifespans. This chart serves as a valuable reference for users to optimize the performance and longevity of their LiFePO4 batteries.

    By referring to these comprehensive voltage charts, users can make informed decisions about voltage levels, charge cycles, and expected lifespans, enabling them to effectively utilize and maintain their LiFePO4 batteries for optimal performance and extended lifespan.

    Continue Reading:

    1. LiFePO4 vs Lithium Ion: A Comprehensive Comparison

    2. A Chart to Understand Lifepo4 Battery

    3. Is LiFePO4 Worth It?

    4. LiFePO4 Lithium Batteries in Series & Parallel: A Comprehensive Overview

    5. Is LiFePO4 Better Than AGM? Exploring Battery Options for Modern Applications

    6. Charging LiFePO4 Batteries: Why Using a Dedicated Charger is Essential

    7. LiFePO4 vs Lead-Acid Batteries: Which One is Better for You?

    8 comments

    Bitte bei 48 Volt auf ein 16 Zellensystem hinweisen. Bei einem 15 Zellensystem wie Pylontech sind die angegebenen Spannungen nicht zutreffend.

    Jobie | Mar 19, 2025

    I think the red discharge current curve should be labeled 0.3 not 1.3

    Robert van den Halsten | Feb 11, 2025

    Dear Mendez,
    
    Thank you for bringing your question to our attention. We appreciate your feedback and are pleased to inform you that the issue you mentioned has been addressed and corrected.
    
    Best regards,
    Zachary

    Zachary | Oct 22, 2024

    In this article below the 12 Volt SOC Table, you list:
    “LiFePO4 Battery Float Charge Voltage: 14.6V”
    Perhaps this is a “typo” error? 14.6V is a fully charged battery. You would never float at this voltage. A safe voltage would be 13.4v-13.5v, way below the voltage of individual cells starting to “drift” from each other…

    Mendez | Oct 21, 2024

    Ich habe LITHUM BATERIEN XL-=60F 07.21 , 3,6 V Keine Akkus. Kann ich die auch laden?.

    Gerhard Petrovic | Aug 12, 2024

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