LiFePO4 Cell Voltage Chart: Comprehensive Guide（3.2V 12V 24V 36V 48V 72V）

935 Published by BSLBATT Aug 09,2024

Lithium iron phosphate (LiFePO4) battery (LFP for short) uses lithium iron phosphate as the positive electrode material, graphite carbon electrode and metal as the negative electrode. Due to its low cost, high energy density, long cycle life, safety and stability, it is widely used in electric vehicles, golf carts, forklifts, RVs, floor machines, scissor lifts, aerial work platforms, marine, airport handling, home storage and industrial and commercial energy storage.

Basics of LiFePO4 Battery Voltage

To better understand LiFepo4 battery voltage, here are some basic definitions.

Nominal Voltage – 3.25V is the nominal voltage of the battery. The standard voltage is used to monitor the charging and discharging of the battery.

Storage Voltage – 3.2V-3.4V If the battery is not used for a long time, it must be stored at this ideal voltage. The storage voltage reduces the loss of battery capacity, thus ensuring that the battery works properly.

Fully Charged Voltage – Charged to 3.65V, which is the maximum voltage. If the battery is charged above this level, it may cause irreparable damage.

Discharge Voltage – 2.5V is the minimum discharge voltage. It is not recommended for users to discharge below this voltage. If the battery is discharged beyond its limit, it may be damaged.

Deep Discharge – In this case, the voltage is below the recommended level. After deep discharge, the LiFePO4 battery may fail completely.

LiFePO4 voltmeter: 12V 24V 36V 48V 72V

SOC	1 cell（3.2Volt）	12 Volt	24 Volt	36 Volt	48 Volt	72 Volt
100% Charging	3.65V	14.6V	29.2V	43.8V	58.4V	87.6V
100% Rest	3.4V	13.6V	27.2V	40.8V	54.4V	81.6V
90%	3.35V	13.4V	26.8V	40.2V	53.6V	80.2V
80%	3.32V	13.28V	26.56V	39.84V	53.12V	79.68V
70%	3.3V	13.2V	26.4V	39.6V	52.8V	79.2V
60%	3.27V	13.08V	26.16V	39.24V	52.32V	78.48V
50%	3.26V	13.04V	26.08V	39.12V	52.16V	78.24V
40%	3.25V	13V	26V	39V	52V	78V
30%	3.22V	12.88V	25.76V	38.64V	51.52V	77.28V
20%	3.2V	12.8V	25.6V	38.4V	51.2V	76.8V
10%	3V	12V	24V	36V	48V	72V
0	2.5V	10V	20V	30V	40V	60V

3.2V LiFePO4 battery voltage meter

• Nominal voltage: 3.2V
• Charging voltage: 3.65V
• Discharge cut-off voltage: 2.5V

lithium iron phosphate cells

SOC	1 cell（3.2Volt）
100% Charging	3.65V
100% Rest	3.4V
90%	3.35V
80%	3.32V
70%	3.3V
60%	3.27V
50%	3.26V
40%	3.25V
30%	3.22V
20%	3.2V
10%	3V
0	2.5V

3.2V LiFePO4 Cell Voltage Chart

12V LiFePO4 battery voltage meter

• Nominal voltage:12.8V
• Charging voltage: 14.6V
• Discharge cut-off voltage: 10V

12v is the ideal voltage for electric bicycles, trolling motors, marine batteries and aerial work platform equipment and home solar

SOC	12 Volt
100% Charging	14.6V
100% Rest	13.6V
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

24V LiFePO4 battery voltage meter

• Nominal voltage:25.6V
• Charging voltage: 29.2V
• Discharge cut-off voltage: 20V

24V LiFePO4 batteries are perfect for use with boat trolling motors, and scissor lifts, boom lifts. Sweepers, floor machines, and RVs energy.
You can buy a 24V LiFePO4 battery, or you can buy two identical 12V LiFePO4 batteries in series.

SOC	24 Volt
100% Charging	29.2V
100% Rest	27.2V
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

36V LiFePO4 battery voltage meter

• Nominal voltage:38.4V
• Charging voltage: 43.8V
• Discharge cut-off voltage: 30V

Golf carts, community electric cars, UTV, ATV are very suitable for 36 Volt LiFePO4 batteries

SOC	36 Volt
100% Charging	43.8V
100% Rest	40.8V
90%	40.2V
80%	39.84V
70%	39.6V
60%	39.24V
50%	39.12V
40%	39V
30%	38.64V
20%	38.4V
10%	36V
0	30V

36V LiFePO4 Cell Voltage Chart

48V LiFePO4 battery voltage meter

• Nominal voltage:51.2V
• Charging voltage: 58.4V
• Discharge cut-off voltage: 40V

48V is the best choice for home solar 5kWh powerwall ,10kWh powerwall, electric golf carts, aerial work platform equipment

SOC	48 Volt
100% Charging	58.4V
100% Rest	54.4V
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

72V LiFePO4 battery voltage meter

• Nominal voltage:76.8V
• Charging voltage: 87.6V
• Discharge cut-off voltage: 60V

Designed for 72V golf carts, electric cars, 6+ seater tour cars, and outboard motors.

SOC	72 Volt
100% Charging	87.6V
100% Rest	81.6V
90%	80.2V
80%	79.68V
70%	79.2V
60%	78.48V
50%	78.24V
40%	78V
30%	77.28V
20%	76.8V
10%	72V
0	60V

LiFePO4 cell Voltage Chart

What is the relationship between the state of charge (SOC) and voltage of a LiFePO4 battery?

The state of charge (SOC) of a battery indicates its charge level relative to its capacity. In terms of SOC, 0% is depleted or discharged, and 100% is fully charged.

DOD is another measurement related to SOC, calculated as 100 – SOC (100% is fully charged, 0% is depleted). While SOC generally indicates the current state of a battery when in use, DOD generally indicates the useful life of a battery after repeated charge and discharge cycles.

When a battery reaches a low state of charge (approaching 0%), the battery management system (BMS) intervenes to prevent over-discharge. Similarly, when a battery approaches a high state of charge (approaching 100%), charging is slowed or stopped to protect the battery.

Example: The discharge capacity of a 100Ah battery is 30Ah. As a result, the SOC is 30%. After charging the battery to 100Ah and discharging it to 70Ah, 30Ah remains.

The following chart shows the correlation between SOC and LiFePO4 voltage for a lithium battery:

SOC	1 cell（3.2Volt）
100% Charging	3.60V-3.65V
100% Rest	3.50V-3.55V
90%	3.45V -3.50V
80%	3.40V -3.45V
70%	3.35V -3.40V
60%	3.30V -3.35V
50%	3.25V -3.30V
40%	3.20V-3.25V
30%	3.10V -3.20V
20%	2.90V – 3.00V
10%	2.90V-2.50V
0	2.5V

Charging Curve

Voltage: It is generally believed that the higher the nominal voltage of a battery, the more fully charged it is. A 3.2V LiFePO4 battery is fully charged when it reaches 3.65V.

Coulombmeter: This device measures the current flowing into and out of the battery and quantifies the rate at which the battery charges and discharges in ampere-seconds (As).

Specific Gravity: A hydrometer is required to measure SOC. The buoyancy of a liquid can be used to measure its density.

State of charge Curve

LiFePO4 battery discharge curve

Discharge refers to the process of extracting electrical energy from a battery to power an electronic device. The discharge curve of a battery usually represents the relationship between voltage and discharge time. The figure below shows the discharge curve of a 12V LiFePO4 battery at different discharge rates.

12V LiFeP04 Discharge Current Curve

LiFePO4 Battery Charging Parameters

Battery performance, health, and durability are ensured by the recommended charging parameters. During charging, each user must adhere to these parameters. Ensure that the battery is not overcharged or undercharged to ensure efficient energy storage and a longer service life. A table of LiFePO4 battery charging parameters can be found below.

Specifications	3.2V	12V	24V	36V	48V	72V
Charging Voltage	3.5-3.65V	14.2-14.6V	28.4-29.2V	42.6-43.8V	56.8-58.4V	83.6-87.6V
Float Voltage	3.2V	13.6V	27.2V	40.8V	54.2V	81.6V
Maximum Voltage	3.65V	14.6V	29.2V	43.8V	58.4V	87.6V
Minimum Voltage	2.5V	10V	20V	30V	40V	60V
Nominal Voltage	3.2V	12/12.8V	24/25.6V	36/38.4V	48V/51.2V	72/76.8V

LiFePO4 battery constant voltage, floating charge and equalization voltage

LiFePO4 batteries have three voltage stages: bulk, float, and equalize. During the bulk stage, a constant current is applied to the battery to quickly charge it to a certain voltage. A maintenance voltage is applied to the battery in the Float stage. As a result, the battery’s efficiency and life are prolonged. While ensuring an even charge, the Equalize stage balances the cells.

Voltage Stages	3.2V	12V	24V	36V	48V	72V
Bulk	3.65V	14.6V	29.2V	43.8V	58.4V	87.6V
Float	3.375V	13.5V	27.V	40.5V	54V	81V
Equalize	3.65V	14.6V	29.2V	43.8V	58.4V	87.6V

How to Check LiFePO4 Battery Capacity

The best way to ensure long-term performance of your LiFePO4 battery is to regularly check and monitor it. LiFePO4 batteries can be accurately measured using the following methods.

· Using a Multimeter-

Multimeters provide accurate voltage readings and battery capacity measurements.

· Battery Monitor-

Battery capacity can be determined with this reliable battery testing method. In addition to evaluating the battery’s health, capacity, voltage, and discharge energy, the battery monitor predicts its life.

· Solar Charge Controller-

LiFePO4 battery capacity is checked by solar charge controllers. Solar power systems can benefit from this method.

· App Monitoring-

LiFePO4 batteries can be monitored and controlled remotely with some batteries. Smartphone apps allow you to monitor performance, voltage, and other features.

The formula for calculating battery capacity is: Capacity = Discharge Current (A) x Discharge Time (Hours).

Visualization of the structure and working principle of LiFePO4 battery

Structure

On the left, LiFePO4 is the positive electrode, connected to the battery’s positive electrode by aluminum foil. In the middle, the polymer separator allows lithium ions (Li+) to pass through while blocking electrons (e-). Copper connects the negative electrode of the battery to the negative electrode of carbon (graphite) on the right.

Visualization of energy structure and working principle of lithium iron phosphate battery-BSLBATT

How it LiFePO4 works

Charging Process:

When LiFePO4 is oxidized, lithium ions (Li+) and electrons (e-) are released.

A negative electrode receives lithium ions (Li+) passing through the electrolyte and separator.

An electrode’s negative electrode stores lithium ions (Li+) in carbon (graphite).

Discharging Process:

Through the electrolyte and separator, lithium ions (Li+) move from the negative electrode to the positive electrode.

A reduction reaction occurs between the lithium ions (Li+) and LiFePO4 at the positive electrode, releasing electrons (e-).

A power supply device is powered by the released electrons (e-) flowing through the external circuit.

The lithium ions (Li+) and electrons (e-) in the battery continue to cycle during charging and discharging.

Factors Affecting the Cycle Life of LiFePO4 Batteries

Relationship Between Temperature and Battery Cycle Numbers LiFePO4 cell Voltage Chart

· Charging and Discharging

It is important not to overcharge or overdischarge the battery. Connecting and disconnecting the charger at the right time is essential. Battery cycle life will be affected by overcharging and overdischarging.

· Depth of Discharge

In order to scientifically extend the service life of lithium iron phosphate batteries, deep discharges should be avoided as much as possible.

· Working Environment

To avoid affecting LiFePO4 battery activity, do not use the battery in a high or low temperature environment. A heated LiFePO4 battery is the best choice if the battery will be used at a lower temperature.

Conclusion

These LiFePO4 voltage charts provide a comprehensive overview of the voltage characteristics of LiFePO4 batteries as well as their capacity, charge cycle, and life expectancy. In order to optimize the performance and life of LiFePO4 batteries, users can refer to this chart.

Using these voltage charts, users can make informed decisions about voltage levels, charge cycles, and life expectancy, ensuring optimal performance and longevity of LiFePO4 batteries.

FAQ

How to tell if my LiFePO4 battery is failing

Of course, a battery won’t last forever. It should last for more than a decade. If you notice any of the following signs, your battery may be failing.

· Charging takes unusually long

· Battery won’t charge

· Battery swelling

· When the battery is fully charged but the device shuts down

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