What is The LiFePO4 Battery Discharge Voltage Cutoff?

By Matthew Joseph Nandirio •  Updated: 11/15/22 •  5 min read

You can use a LiFePO4 battery up to 100% depth of discharge. However, manufacturers recommend using 80% DOD. In both cases, this battery has more usable capacity than others.

But you might ask, what’s the discharge voltage cutoff of a LiFePO4 battery? Well, I’ll explain that in this write-up to understand better-charging conditions for your LiFePO4. So, let’s get going.

What Is The LiFePO4 Battery Discharge Voltage Cutoff?

The discharge voltage cutoff for a

  • 12V LiFePO4 battery is 10V,
  • 20V for a 24V battery, and
  • 40V for a 48V battery. 

LiFePO4 Battery Voltage Chart for Various Voltages 

Here’s a table showing the voltage chart and cutoff point of LiFePO4 batteries at various voltages. 

Capacity3.2V12V24V48V
100% Charging3.65V14.6V29.2V58.4V
100% Resting3.4V13.6V27.2V54.4V
99%3.35V13.4V26.8V53.6V
90%3.33V13.3V26.6V53.2V
70%3.3V13.2V26.4V52.8V
40%3.28V13.1V26.2V52.4V
30%3.25V13.0V26.0V52.0V
20%3.23V12.9V25.8V51.6V
17%3.2V12.8V25.8V51.2V
14%3.13V12.5V25.0V50.0V
9%3.0V12.0V24.0V48.0V
Cutoff2.5V10.0V20.0V 40.0V
LiFePO4 Battery Voltage Chart for Various Voltages 

We know that discharge cutoff voltage means the battery should not be discharged any longer when it reaches a certain voltage point. Since the LiFePO4 battery has a battery management system, when it tries to reach beyond the voltage cutoff point, BMS will put the battery in sleep mode.

Let’s discuss the cutoff voltages of various LiFePO4 batteries.

Voltage Cutoff Point For 3.2V LiFePO4 Battery 

A single LiFePO4 battery cell has a 3.2V nominal voltage. When you fully charge, it’ll reach 3.65V. And while discharging, the battery will discharge to 2.5 volts. So, the cutoff voltage of a 3.2V LiFePO4 battery is 2.5V.

3.2V LiFePO4 Battery Cutoff Point
3.2V LiFePO4 Battery Cutoff Point

When your battery reaches this point, the BMS will detect it. If your battery discharges further down, the BMS will put it in sleep mode to protect the battery from damage.

Voltage Cutoff Point For 12V LiFePO4 Battery 

Generally, A 12V LiFePO4 battery consists of 4 3.2V LiFePO4 battery cells. When the battery is fully charged, it will reach 14.6V. Typically, manufacturers recommend using a LiFePO4 battery up to 80% depth of discharge.

12V LiFePO4 Battery Cutoff Point
12V LiFePO4 Battery Cutoff Point

So, when the battery capacity reaches 20%, its voltage will become 12.9V. But the cutoff voltage for a 12V battery is 10V. Further discharge will damage the battery.

To protect your battery from any damage, the battery management system will send your battery to sleep mode if it starts discharging beyond 10V.

Voltage Cutoff Point For 24V LiFePO4 Battery 

When a 24V battery reaches 100% battery capacity after a full charge, the voltage of the battery will reach 29.2V. And after 80% depth of discharge, the voltage will be 25.8V.

24V LiFePO4 Battery Cutoff Point
24V LiFePO4 Battery Cutoff Point

But the cutoff point of a 24V LiFePO4 battery is 20V. So, the BMS will not allow your 24V LiFePO4 battery to discharge beyond 20V. It will put the battery to sleep to prevent further discharge.

Voltage Cutoff Point For 48V LiFePO4 Battery 

48V batteries are very popular among people who have large solar systems. When fully charged, it reaches 58.4 volts. After 80% depth of discharge, the battery becomes 51.6 volts.

48V LiFePO4 Battery Cutoff Point
48V LiFePO4 Battery Cutoff Point

However, the cutoff point of this 48-volt LiFePO4 battery is 40V. So, the battery management system won’t allow your 48V battery to discharge below 40V.

Why is Cutoff On Proper Value Important? 

A cutoff point of a battery is the voltage at which the battery becomes fully discharged. And further discharging will cause harm to your battery.

The cutoff point on the proper value for a LiFePO4 battery is vital for several reasons. Let’s explore some of them.

Shows the Safe Level of Using A Battery 

A cutoff point is the lowest capacity you should use your battery. Generally, the cutoff point is the 0% battery capacity for LiFePO4 batteries. So, it shows that you should discharge your battery up to 0% capacity.

Although manufacturers prefer 80% depth of discharge, 100% DOD won’t damage your battery in the long run. So, the cutoff point shows the safe level up to which you can use your battery.

Protect Battery from Damages

According to a research paper published in IEEEExplore journal, “an important responsibility of the cutoff voltage point is to protect the battery from any damage.”

When the battery reaches 0% capacity, further discharge can create an imbalance in the battery chemistry and damage your LiFePO4 battery.

That’s why LiFePO4 batteries’ integrated battery management system sends the battery in sleep mode when it starts discharging beyond the cutoff point.

Final Thoughts 

A cutoff point is a crucial indicator that tells you the safe voltage level you can discharge your battery. So, now that you know the cutoff points of various LiFePO4 battery voltages, you can use your battery correctly now.

References

  1. S. Xin et al. (2019). Optimization of the discharge cutoff voltage in LiFePO 4 battery packs.
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Matthew Joseph Nandirio

Matthew Joseph Nandirio is the Founder of walkingsolar. After graduating from the University of Houston in 2002, matt started working as an electrical and electronic engineer for several multi-national solar energy companies. He has a wide range of experiences including solar system requirement analysis, planning, maintaining, debugging and even solar device development through research. He now shares his 20 years of expertise through his articles on the walkingsolar website. Further, he is also the author of two books on Solar Technology, “Solar Power for Villages” and “DIY Solar System for Dummies”.

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