Reference
LiFePO4 Voltage Chart: 12V, 24V & 48V State of Charge
A 12V LiFePO4 battery reads about 13.6V at full charge and around 12.9V near empty, with the whole usable range packed into a tiny voltage window. That flat curve is exactly why voltage is only a rough fuel gauge for lithium. Use the charts below for a quick estimate, but read the caveats before you trust a number.
All readings below are resting (no-load) voltage, measured after the battery has been off the charger and off any load for at least 30 minutes. LiFePO4 has a famously flat discharge curve, so these figures are approximate. A single reading places you in a broad zone, not at an exact percentage.
12V LiFePO4 voltage to state of charge
| Resting voltage | State of charge |
|---|---|
| 13.6V | 100% |
| 13.4V | 99% |
| 13.3V | 90% |
| 13.2V | 70% |
| 13.1V | 40% |
| 13.0V | 30% |
| 12.9V | 20% |
| 12.8V | 17% |
| 12.5V | 14% |
| 12.0V | 9% |
| 10.0V | 0% (BMS cutoff) |
24V LiFePO4 voltage to state of charge
Same battery chemistry, double the cells. Each voltage is the 12V figure multiplied by two.
| Resting voltage | State of charge |
|---|---|
| 27.2V | 100% |
| 26.8V | 99% |
| 26.6V | 90% |
| 26.4V | 70% |
| 26.2V | 40% |
| 26.0V | 30% |
| 25.8V | 20% |
| 25.6V | 17% |
| 25.0V | 14% |
| 24.0V | 9% |
| 20.0V | 0% (BMS cutoff) |
48V LiFePO4 voltage to state of charge
The common choice for cabins and whole-home banks. Each voltage is the 12V figure multiplied by four.
| Resting voltage | State of charge |
|---|---|
| 54.4V | 100% |
| 53.6V | 99% |
| 53.2V | 90% |
| 52.8V | 70% |
| 52.4V | 40% |
| 52.0V | 30% |
| 51.6V | 20% |
| 51.2V | 17% |
| 50.0V | 14% |
| 48.0V | 9% |
| 40.0V | 0% (BMS cutoff) |
LiFePO4 vs lead-acid: 12V resting voltage
This is where the two chemistries part ways. A lead-acid battery's voltage slopes steadily as it drains, so voltage is a usable gauge, but you can only safely use about half its capacity. LiFePO4 holds a near-flat voltage while delivering far more usable energy.
| State of charge | LiFePO4 (12V) | Lead-acid (12V) |
|---|---|---|
| 100% | 13.6V | 12.70V |
| 90% | 13.3V | 12.50V |
| 80% | ~13.3V | 12.42V |
| 70% | 13.2V | 12.32V |
| 50% | ~13.1V | 12.06V |
| 20% | 12.9V | 11.58V |
| 10% | ~12.5V | 11.31V |
| 0% | 10.0V (cutoff) | < 11.30V |
LiFePO4 percentages above are mapped from the 12V chart; the tilde figures fall on the flat plateau and are approximate.
LiFePO4 charging voltages
These are charger and solar charge controller targets, not resting readings. Set your charge profile to these values, and scale up for 24V and 48V banks.
| Stage | 12V | 24V | 48V |
|---|---|---|---|
| Bulk / absorption | 14.2–14.6V | 28.4–29.2V | 56.8–58.4V |
| Float | 13.6V (or none) | 27.2V (or none) | 54.4V (or none) |
Many people running LiFePO4 turn float off entirely. Lithium does not need the trickle top-up that lead-acid relies on, so a low float or no float at all is healthier for the cells over the long run.
Why voltage is a poor fuel gauge for LiFePO4
Look back at the 12V chart. The battery sits between about 13.3V and 13.0V across most of its usable range, which means a swing of a few hundredths of a volt covers a huge chunk of capacity. That flat plateau is great for your gear, since the voltage your devices see barely changes as the battery drains, but it makes voltage almost useless for telling how full the battery actually is.
Two things make it worse. The battery has to rest for 30 minutes or more after charging or discharging before the reading settles, and under any real load the voltage sags below its true resting value. So a quick glance at a voltmeter while the fridge is running can easily be off by a full state-of-charge zone.
The fix is a shunt-based battery monitor. Instead of guessing from voltage, a shunt counts every amp going in and out and reports an accurate percentage, much like a fuel gauge in a car. If you rely on your battery daily, it is the single most useful upgrade you can add. See our roundup of the best battery monitors for the accurate alternative to reading voltage.
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What voltage should I stop discharging at?
As a daily-use floor, do not routinely pull a 12V LiFePO4 battery below about 12.0V at rest, which lands near the bottom of the usable range. You can use far more of a LiFePO4 battery than a lead-acid one, but draining to the absolute bottom every cycle still shortens its life over time.
The BMS will eventually disconnect the battery near 10.0V to protect the cells from damage, but that cutoff is an emergency stop, not a target. Think of it like the engine cutting out when you run a fuel tank bone dry. It saves the hardware, but you never want to be the person who relies on it. Recharge before you get close.
LiFePO4 vs lead-acid voltage in plain terms
With lead-acid you only use the top half of the tank. Drain a lead-acid battery past about 50% regularly and you wear it out fast, which is why its 100%-to-50% window (roughly 12.7V down to 12.06V) is the part that matters in practice.
LiFePO4 flips that. You can comfortably use 80% to 100% of its rated capacity, cycle after cycle, with no harm. So even though a 100Ah lead-acid battery and a 100Ah LiFePO4 battery list the same number, the lithium one gives you nearly twice the usable energy. The flat voltage curve is the trade-off you accept for that extra capacity.
How to use these charts
- Match readings to your system voltage: use the 12V table for a van, the 24V or 48V table for a larger cabin bank.
- Pair the chart with the right charge profile from your MPPT charge controller so charging and resting numbers both make sense.
- Sizing a new bank? Run the numbers in the battery bank calculator instead of guessing from voltage.
- New to all of this? Start with LiFePO4 vs lead-acid to see why lithium changed off-grid storage.
Methodology: 12V LiFePO4 and charging figures are conservative, widely-published values cross-checked against manufacturer-sourced data (LiTime and Renogy LiFePO4 voltage guides, plus Footprint Hero's manufacturer-derived chart, which matched our 13.6V/13.3V/13.2V/13.1V/12.9V points and the 14.2–14.6V charge and 13.6V float targets exactly). The 24V and 48V tables scale the 12V values by 2x and 4x. Lead-acid figures are standard flooded/AGM open-circuit values. LiFePO4 is a flat-curve chemistry, so treat every reading as approximate and rest the battery first.
Frequently Asked Questions
What voltage is a 12V LiFePO4 at 50%?
There is no clean 50% voltage, and that is the whole problem with using voltage on LiFePO4. The curve is so flat that most of the middle band sits between about 13.0V and 13.2V at rest. A reading in that range tells you the battery is somewhere in the broad 20% to 70% zone, not a precise number. For an actual percentage you need a shunt-based monitor.
Is 13.2V good for LiFePO4?
Yes, 13.2V at rest is a healthy reading. It puts the battery in the comfortable mid-to-upper range, roughly 70% charged, with plenty of usable energy left. There is nothing to worry about at 13.2V. You only start paying attention once a rested reading drops toward 12.9V or below.
At what voltage is a LiFePO4 battery dead?
A 12V LiFePO4 battery is essentially empty by the time it reaches about 12.0V at rest, and the BMS will disconnect the battery near 10.0V to protect the cells. That cutoff is a last-resort safety stop, not a daily target. Treat roughly 12.0V to 12.9V as your low-fuel warning and recharge before you get there.
Why does my battery voltage drop under load?
When you pull current, the battery's internal resistance causes the terminal voltage to sag, so a battery that reads 13.3V at rest might show 12.9V while a draw is running. This is normal and recovers the moment the load stops. It also means you cannot trust a voltage reading taken while the inverter or fridge is running. Let the battery rest first.
What voltage should I charge LiFePO4 to?
For a 12V LiFePO4 battery, set bulk and absorption to roughly 14.2V to 14.6V, and either disable float or set it low at about 13.6V. Double those numbers for 24V and quadruple them for 48V. Always follow the figures in your specific battery's manual, since BMS limits vary slightly between brands.