What voltage is 50% on a 12V LiFePO4 battery?

About 13.0V after the battery has rested 30 minutes with no load and no charger attached. Under load or right after charging, the same battery reads higher or lower, so resting voltage is the only reading worth charting.

Why does LiFePO4 voltage look stuck between 20% and 100%?

The discharge curve is flat by design: a cell sits between roughly 3.20V and 3.35V across most of its usable capacity, then falls off a cliff below 10%. That flatness is great for powering equipment and poor for gauging charge, which is why a coulomb-counting meter beats voltage-only estimates.

What low-voltage cutoff should I set for a 12V LiFePO4 bank?

Set the inverter low-voltage disconnect around 10.5 to 11.0V rather than riding the BMS cutoff at 10.0V. The BMS cut is a protection last resort; a soft cutoff above it avoids deep-discharge stress and nuisance shutdowns under load sag.

LiFePO4 Voltage Chart: 12V, 24V and 48V SoC Tables

LiFePO4 cells hold a nearly flat voltage across most of their capacity. That flatness is why lithium iron phosphate packs run equipment so well, and it is also the reason voltage is a clumsy way to guess state of charge. The tables below give the resting voltages worth memorizing, the charge and float setpoints, and the cutoffs that actually protect the pack.

Resting voltage by state of charge

Measure after the battery has sat 30 minutes with no load and no charger. Readings taken under load or during charging will not match these numbers.

SoC	Per cell	12V (4S)	24V (8S)	48V (16S)
100%	3.40 V	13.60 V	27.20 V	54.40 V
90%	3.35 V	13.40 V	26.80 V	53.60 V
80%	3.33 V	13.32 V	26.64 V	53.28 V
70%	3.31 V	13.24 V	26.48 V	52.96 V
60%	3.29 V	13.16 V	26.32 V	52.64 V
50%	3.27 V	13.08 V	26.16 V	52.32 V
40%	3.25 V	13.00 V	26.00 V	52.00 V
30%	3.23 V	12.92 V	25.84 V	51.68 V
20%	3.20 V	12.80 V	25.60 V	51.20 V
10%	3.05 V	12.20 V	24.40 V	48.80 V
0%	2.50 V	10.00 V	20.00 V	40.00 V

Notice how 100% down to 20% fits inside a 0.2V-per-cell window. Then 10% to 0% drops more than half a volt per cell. The flat middle is normal chemistry, not a broken meter.

Charge, float and cutoff setpoints

Charge (absorption) voltage: 3.65V per cell, which works out to 14.6V for a 12V bank, 29.2V for 24V, and 58.4V for 48V. Set your charger or inverter to match this before first use.
Float: around 3.375V per cell (13.5V / 27.0V / 54.0V). LiFePO4 does not need a true float; if the charger allows it, disable float or keep it low.
BMS low cutoff: 2.5V per cell (10.0V / 20.0V / 40.0V). This is a last-resort protection, not a daily operating point.
Recommended inverter low-voltage disconnect: 10.5 to 11.0V on a 12V bank (21.0-22.0V / 42.0-44.0V for 24V / 48V). Cutting above the BMS limit keeps the pack out of deep-discharge stress and avoids nuisance trips when heavy loads sag the voltage.

How to use these numbers without fooling yourself

Voltage reads high for an hour or two after charging and sags under any real load. A bank at 13.3V on the meter while the inverter is pushing 1500W may actually be near half, not 80%. For anything you care about, put a coulomb-counting battery meter on the bank and treat the voltage chart as a sanity check, not the primary gauge. If you are still choosing the system architecture first, our 12V/24V/48V comparison covers which voltage makes sense for which load size, and the sizing guide walks the capacity math.

We build 12V, 24V and 48V LiFePO4 packs on our Dongguan line, every cell matched and every pack shipped with a capacity test report. Questions about setpoints for a specific inverter? Contact us.