Complete Lithium Battery Voltage Chart
Use this Lithium Battery Voltage Chart to understand how battery voltage relates to state of charge for LiFePO4, Li-ion, and LiPo batteries. Lithium batteries do not discharge in a perfectly straight line. Their voltage changes depending on chemistry, state of charge, load, temperature, battery age, BMS settings, and how long the battery has rested after charging or discharging.
Voltage is one of the quickest ways to estimate battery state of charge, but it is not always exact. A battery under load may show lower voltage than the same battery at rest. A battery fresh off the charger may show higher voltage for a short time. For best accuracy, measure open-circuit voltage after the battery has rested and compare the reading with the correct chemistry chart.
LiFePO4 Voltage vs SOC Table
| State of Charge | LiFePO4 Cell Voltage | 12V Pack (4S) | 24V Pack (8S) | 48V Pack (16S) |
|---|---|---|---|---|
| 100% | 3.65V | 14.6V | 29.2V | 58.4V |
| 90% | 3.35V | 13.4V | 26.8V | 53.6V |
| 80% | 3.32V | 13.28V | 26.56V | 53.12V |
| 70% | 3.30V | 13.20V | 26.40V | 52.80V |
| 60% | 3.29V | 13.16V | 26.32V | 52.64V |
| 50% | 3.28V | 13.12V | 26.24V | 52.48V |
| 40% | 3.27V | 13.08V | 26.16V | 52.32V |
| 30% | 3.25V | 13.00V | 26.00V | 52.00V |
| 20% | 3.22V | 12.88V | 25.76V | 51.52V |
| 10% | 3.00V | 12.00V | 24.00V | 48.00V |
| 0% | 2.50V | 10.00V | 20.00V | 40.00V |
Li-ion / LiPo Voltage vs SOC Table
| State of Charge | Li-ion / LiPo Cell Voltage | 2S Pack | 3S Pack | 4S Pack |
|---|---|---|---|---|
| 100% | 4.20V | 8.40V | 12.60V | 16.80V |
| 90% | 4.10V | 8.20V | 12.30V | 16.40V |
| 80% | 3.95V | 7.90V | 11.85V | 15.80V |
| 70% | 3.83V | 7.66V | 11.49V | 15.32V |
| 60% | 3.75V | 7.50V | 11.25V | 15.00V |
| 50% | 3.70V | 7.40V | 11.10V | 14.80V |
| 40% | 3.65V | 7.30V | 10.95V | 14.60V |
| 30% | 3.60V | 7.20V | 10.80V | 14.40V |
| 20% | 3.50V | 7.00V | 10.50V | 14.00V |
| 10% | 3.30V | 6.60V | 9.90V | 13.20V |
| 0% | 3.00V | 6.00V | 9.00V | 12.00V |
Why Use Our Lithium Battery Voltage Chart
Estimate State of Charge
Voltage gives a quick way to estimate how full a lithium battery is. Compare measured battery voltage with the correct chemistry chart to get a rough SOC estimate.
Compare Lithium Chemistries
LiFePO4, Li-ion, and LiPo batteries have different voltage ranges. This chart helps you avoid using the wrong voltage limits for the wrong battery chemistry.
Check Pack Voltages
Battery packs are built from cells in series. The chart shows cell voltage and common pack voltages so you can understand 12V, 24V, 48V, 2S, 3S, and 4S systems.
Protect Battery Health
Knowing safe full-charge and low-voltage limits helps prevent overcharging and overdischarging, both of which can reduce battery life or trigger BMS protection.
Plan Solar and RV Systems
Solar controllers, inverters, chargers, and battery monitors use voltage settings. A voltage chart helps you understand charge, discharge, and cutoff values.
Troubleshoot Battery Problems
Unexpected voltage readings can indicate low charge, imbalance, voltage sag, BMS cutoff, wrong charger settings, or possible battery damage.
LiFePO4 Battery Voltage Chart Explained
LiFePO4 batteries have a very flat voltage curve compared with many other battery chemistries. A LiFePO4 cell may stay around 3.2V to 3.35V through a large part of its usable capacity. This is excellent for stable power delivery, but it also makes voltage-based state of charge estimation less precise in the middle of the discharge curve.
A fully charged LiFePO4 cell is commonly around 3.65V at the end of charging. A 12V LiFePO4 battery normally uses four cells in series, so full charge is about 14.6V. A 24V pack uses eight cells, so full charge is about 29.2V. A 48V or 51.2V LiFePO4 system often uses sixteen cells in series, so full charge may be about 58.4V.
The nominal voltage of a LiFePO4 cell is usually about 3.2V. That means a 4-cell pack is often called 12.8V nominal, an 8-cell pack is 25.6V nominal, and a 16-cell pack is 51.2V nominal. Many people still call these 12V, 24V, and 48V systems because they are designed to replace traditional lead-acid battery system classes.
Li-ion and LiPo Battery Voltage Chart Explained
Li-ion and LiPo batteries commonly use a nominal cell voltage around 3.6V to 3.7V. A fully charged standard Li-ion or LiPo cell is usually 4.20V. A low cutoff is often around 3.0V per cell, although exact limits depend on battery chemistry, manufacturer guidance, load, and protection circuitry.
LiPo packs are often described by series count, such as 2S, 3S, 4S, or 6S. A 3S LiPo battery has three cells in series. At full charge, it is 12.6V because 4.20V × 3 = 12.6V. At nominal voltage, it is commonly around 11.1V because 3.7V × 3 = 11.1V. At low voltage, it may be around 9.0V if using 3.0V per cell as the cutoff reference.
Unlike LiFePO4, Li-ion and LiPo voltage usually declines more visibly across the discharge range. This can make voltage-based SOC estimation somewhat easier, but load and temperature still affect readings. High-current loads can cause voltage sag, making the battery appear lower than it really is until the load is removed.
Fully Charged Lithium Battery Voltages
A fully charged LiFePO4 cell is commonly 3.65V. A fully charged 12V LiFePO4 battery with four cells in series is about 14.6V. A fully charged 24V LiFePO4 battery is about 29.2V, and a fully charged 48V-class 16-cell LiFePO4 battery is about 58.4V.
A fully charged Li-ion or LiPo cell is commonly 4.20V. A 2S pack is 8.4V full, a 3S pack is 12.6V full, and a 4S pack is 16.8V full. Some special high-voltage lithium cells use different charging limits, so the correct datasheet should always be followed.
Using the wrong charger voltage can damage a lithium battery. A charger designed for Li-ion/LiPo cells should not be used on LiFePO4 unless it has the correct profile and voltage settings. LiFePO4 batteries charge to a lower voltage per cell than standard Li-ion cells, so chemistry-specific charging matters.
Low Voltage and Cutoff Limits
Low-voltage cutoff protects lithium batteries from excessive discharge. For LiFePO4 cells, 2.5V per cell is often treated as a hard lower cutoff. For a 4-cell 12V LiFePO4 pack, that corresponds to about 10.0V. However, many battery systems use higher practical cutoff values to improve cycle life and avoid deep discharge stress.
For Li-ion and LiPo cells, 3.0V per cell is a common lower reference. Some systems may cut off slightly above this level under load. Deeply discharging Li-ion or LiPo batteries below the recommended limit can reduce capacity, increase internal resistance, or create safety risks.
A battery management system can disconnect the battery when voltage gets too low. If a lithium battery suddenly shuts off even though it was working moments earlier, the BMS may have reached a low-voltage protection point. Recharge the battery with the correct charger and check the manufacturer's instructions if the battery does not recover normally.
Why Voltage Readings Can Be Misleading
Voltage is useful, but it is not a perfect fuel gauge. A battery under load shows voltage sag because current flow causes voltage drop inside the cells, wiring, and connections. When the load is removed, voltage may rebound. A battery being charged may show higher voltage than its resting state of charge would suggest.
Temperature also affects voltage. Cold batteries may show lower voltage and reduced power capability. Warm batteries may behave differently. Battery age, cell balance, internal resistance, and recent charging history all affect voltage readings. For this reason, a dedicated battery monitor with a shunt is often more accurate for tracking state of charge over time.
LiFePO4 batteries are especially difficult to estimate by voltage in the middle of their range because their voltage curve is very flat. A small voltage difference can represent a large SOC change. Voltage is best used as a rough guide or safety check, not as the only measurement for critical energy planning.
How to Measure Lithium Battery Voltage Correctly
For the best voltage-based SOC estimate, disconnect major loads and chargers, then let the battery rest before measuring. Rest time allows surface charge and voltage sag to settle. Use a reliable digital multimeter and measure at the battery terminals. If measuring at the end of a long cable run, voltage drop may make the reading lower than actual battery terminal voltage.
When checking a battery pack, compare the pack voltage with expected pack voltage. If possible and safe, check individual cell group voltages as well. A pack can show a normal total voltage while one cell group is too high or too low. Cell imbalance is one reason lithium batteries use a BMS.
Always follow safety precautions when measuring batteries. Lithium battery packs can deliver high current if shorted. Use insulated tools, avoid jewelry, protect meter probes from slipping, and do not open sealed battery packs unless you are qualified and the manufacturer allows service access.
Voltage Settings for Chargers and Inverters
Chargers, solar charge controllers, and inverters must be configured for the correct battery chemistry. LiFePO4 batteries usually need different charge voltage settings than lead-acid or Li-ion packs. For example, a 12V LiFePO4 battery may charge to around 14.2V to 14.6V depending on manufacturer guidance. Float charging may be unnecessary or set lower than lead-acid float values.
Inverter low-voltage cutoff should also match the battery type. If the cutoff is too low, the battery may be deeply discharged. If it is too high, usable capacity may be reduced. Many lithium batteries have internal BMS cutoff protection, but relying only on emergency BMS cutoff is not ideal for normal operation.
For solar systems, charge controller settings should match the battery datasheet. Bulk, absorption, float, equalization, and low-temperature charge protection settings all matter. Equalization should generally be disabled for lithium batteries unless the manufacturer specifically instructs otherwise.
Common Mistakes to Avoid
- Using the wrong chemistry chart: LiFePO4 and Li-ion/LiPo have different voltage ranges. Do not use a Li-ion chart for LiFePO4 batteries.
- Judging SOC under heavy load: Voltage sag can make a battery look emptier than it is. Let the battery rest for a better estimate.
- Charging to the wrong voltage: Using an incorrect charger profile can overcharge or undercharge lithium batteries.
- Discharging below cutoff: Deep discharge can damage lithium cells and may trigger BMS protection.
- Ignoring cell imbalance: Total pack voltage can hide an overcharged or undercharged cell group.
- Assuming voltage is exact SOC: Voltage gives an estimate, but a shunt-based monitor is better for accurate capacity tracking.
Lithium Battery Voltage Planning Checklist
Before setting up a lithium battery system, identify the exact battery chemistry, nominal voltage, cell count, full-charge voltage, recommended charging voltage, low-voltage cutoff, maximum charge current, maximum discharge current, and BMS protection limits. These values should come from the battery label, datasheet, or manufacturer manual.
Next, configure all connected equipment correctly. Solar charge controllers, AC chargers, DC-DC chargers, inverters, battery monitors, and low-voltage disconnects should all match the battery chemistry. Wrong settings may reduce battery life or cause unexpected shutdowns.
Finally, monitor battery behavior during real use. Check voltage at rest, under load, and during charging. Watch for unusual voltage sag, failure to reach full charge, rapid voltage drop, or imbalance warnings. A voltage chart is a helpful reference, but final troubleshooting should rely on manufacturer data and proper measurement tools.
Related Tools
Use these related calculators and guides to continue your lithium battery planning workflow:
- Battery State of Charge Calculator
- LiFePO4 Battery Calculator
- Lithium Battery Calculator
- Battery Runtime Calculator