Lithium batteries don’t all share the same voltage. A 12 V LiFePO4 house battery, a 12 V NMC lithium battery for a boat, and a LiPo pack for a drone can all say “12 V” on the label but behave very differently on a voltage chart.
This guide puts all the common lithium chemistries on the same page: how their cell voltages compare, how LiFePO4 stands out, how to read a lithium battery voltage chart or SOC chart, and how charging voltage affects lifetime and safety.
What Is Lithium Battery Voltage?
Nominal vs full vs empty voltage
When people talk about lithium battery voltage, they may mean three different things:
- Nominal voltage – a “middle” value used for naming the battery (e.g. 3.6 V cell, 12.8 V pack). It is not the full-charge voltage.
- Full-charge voltage – the maximum voltage the battery reaches at the end of a proper charge (e.g. 4.2 V per Li-ion cell, 3.65 V per LiFePO4 cell).
- Empty or cut-off voltage – the minimum safe voltage. Below this the BMS should disconnect to avoid damage (e.g. 3.0 V per typical Li-ion cell, ~2.5 V per LiFePO4 cell).
A lithium voltage chart usually shows open-circuit voltage (resting voltage with no load) versus state of charge (SOC), plus recommended charging and cut-off limits.
Pack voltage vs single cell voltage
Lithium packs are built from cells in series:
- Li-ion / LiPo:
- 1 S ≈ 3.6–3.7 V nominal
- 3 S ≈ 10.8–11.1 V nominal (often called a “12 V lithium battery”)
- LiFePO4 (LFP):
- 1 S ≈ 3.2 V nominal
- 4 S ≈ 12.8 V nominal (standard “12 V LiFePO4 battery”)
Every lithium battery chart you see is based on cell voltage; pack voltage is simply cell voltage × number of cells in series.
Why lithium voltage is higher than lead-acid
A 12 V lead-acid battery has:
- Nominal ≈ 12.0 V
- Fully charged ≈ 12.6–12.8 V
- Empty ≈ 11.8 V or lower
A 12 V LiFePO4 battery sits much higher:
- Nominal ≈ 12.8 V
- Fully charged ≈ 13.6–14.4 V (depending on charger profile)
- BMS cut-off typically ≈ 10–11 V
That higher and more stable voltage is why lithium batteries deliver better performance under load, but it also means your charger and DC equipment must be compatible.
Lithium Cell Voltages by Chemistry
The main chemistries you’ll see on a lithium battery voltage chart are:
| Chemistry / Abbrev. | Typical Use | Nominal V / cell | Full charge V / cell | Min. V (cut-off) / cell* |
|---|---|---|---|---|
| Li-ion NMC/NCA | Power tools, e-bikes, home storage | 3.6–3.7 V | 4.2 V | 2.7–3.0 V |
| Li-ion LCO | Older consumer electronics | 3.6–3.7 V | 4.2 V | 3.0 V |
| LiFePO4 (LFP) | RV / marine / solar / starter upgrades | 3.2–3.3 V | 3.65 V | 2.5–2.8 V |
| LiPo (polymer) | RC models, drones, FPV | 3.7 V | 4.2 V | 3.0–3.3 V |
*Cut-off values depend on the BMS and manufacturer.
Lithium-ion (NMC / NCA / LCO) voltage range
For a typical lithium-ion battery:
- 4.2 V / cell – 100 % SOC (immediately after charge)
- ~3.7–3.8 V / cell – ~50 % SOC
- 3.0–3.2 V / cell – near empty
A 3 S lithium battery voltage chart (often used for “12 V” packs) will therefore show:
- ~12.6 V full
- ~11.1 V nominal
- ~9.0–9.6 V empty
LiFePO4 cell voltage range
For LiFePO4 batteries:
- 3.65 V / cell – full charge
- 3.2–3.3 V / cell – nominal
- 2.8 V / cell – roughly 10–20 % SOC
- 2.5 V / cell – BMS low-voltage cut-off for many packs
LiFePO4 works well in deep-cycle use because it tolerates frequent cycling in the 10–90 % SOC band with less stress than NMC-type chemistries.
LiPo battery voltage chart basics
LiPo packs (lithium polymer) are essentially Li-ion cells packaged in a soft pouch. Their voltage numbers match NMC/LCO:
- 4.2 V / cell – full
- 3.8 V / cell – common “storage voltage” point
- 3.3 V / cell – many RC users treat as “land now”
- <3.0 V / cell – risk of permanent damage
A typical 4 S LiPo battery voltage chart for drones will show 16.8 V full and a recommended landing point around 14.8–15.2 V.
LiFePO4 Voltage Chart (Cell & Packs)
3.2 V LiFePO4 cell voltage chart
At 25 °C and resting (no load for at least 30 minutes), a LiFePO4 cell behaves approximately like this:
| SOC (%) | Voltage (V/cell) |
|---|---|
| 100 % | 3.40–3.45 |
| 90 % | 3.36–3.38 |
| 80 % | 3.33–3.35 |
| 70 % | 3.30–3.32 |
| 60 % | 3.28–3.30 |
| 50 % | 3.25–3.27 |
| 40 % | 3.23–3.25 |
| 30 % | 3.21–3.23 |
| 20 % | 3.18–3.20 |
| 10 % | 3.05–3.15 |
| 0–5 % | 2.50–3.00 |
Notice how tight the band is between 40 % and 80 % SOC; this is the “flat” part of the LiFePO4 discharge curve.
12 V LiFePO4 battery voltage chart
A “12 V” LiFePO4 battery is usually 4 S (four cells in series). Multiply by 4 to get pack voltage:
| SOC (%) | Pack Voltage (V, 4 S LiFePO4) |
|---|---|
| 100 % | 13.6–13.8 |
| 90 % | 13.4–13.5 |
| 80 % | 13.3–13.4 |
| 70 % | 13.2–13.3 |
| 60 % | 13.1–13.2 |
| 50 % | 13.0–13.1 |
| 40 % | 12.9–13.0 |
| 30 % | 12.7–12.9 |
| 20 % | 12.4–12.7 |
| 10 % | 12.0–12.4 |
| 0–5 % | 10.0–12.0 (approaching cut-off) |
This LiFePO4 voltage chart is what people use to estimate SOC from a multimeter reading on RV, boat and home-storage systems.
24 V & 48 V LiFePO4 pack voltages
For quick reference:
- 24 V LiFePO4 (8 S):
- Nominal: 25.6 V
- Full: ≈ 27.2–27.6 V
- Typical low-voltage cut-off: 20–21 V
- 48 V LiFePO4 (16 S):
- Nominal: 51.2 V
- Full: ≈ 54.4–55.2 V
- Typical low-voltage cut-off: 40–42 V
Once you know the lithium battery chart for one cell, you can scale it to any series configuration.
How Is LiFePO4 Voltage Different?
Flatter discharge curve vs other lithium chemistries
On a graph, Li-ion (NMC / LCO) shows a noticeable slope: voltage steadily falls from 4.2 V down to 3.3 V as SOC drops.
LiFePO4 is different:
- It quickly settles around 3.3–3.4 V after charging
- It stays almost flat between about 80 % and 20 % SOC
- Then it falls sharply near the bottom
This flatter discharge curve is great for inverters and 12 V appliances, because they see nearly constant voltage. But it also makes a lithium battery SOC chart more compressed and harder to read without context.
Cut-off voltage and BMS settings
Because LiFePO4 has a lower per-cell voltage:
- A “low SOC” cell may still read ~3.0 V
- The BMS typically cuts off around 2.5–2.8 V / cell (10–11 V for a 4 S pack)
If you copy Li-ion cut-off values (like 3.0 V per cell) to LiFePO4, you’ll leave a huge chunk of usable capacity unused.
When LiFePO4 looks “empty” but isn’t
A common confusion:
“My LiFePO4 battery still reads 13.0 V; why does my monitor say 50 %?”
Because in LiFePO4, 13.0 V is only mid-pack. You must use a chemistry-specific lithium voltage chart – not a generic “12 V battery chart” copied from lead-acid or NMC.
Lithium Battery SOC vs Voltage
SOC definition for lithium-ion batteries
State of charge (SOC) is the percentage of remaining capacity in the battery:
- 100 % SOC – fully charged
- 0 % SOC – the lowest allowed discharge point set by the BMS
Voltage is one way to infer SOC, but especially for lithium batteries, it’s only part of the story.
Lithium battery SOC chart at rest
A typical lithium battery SOC chart assumes:
- The battery is at 25 °C
- It has been resting with no load or charger for at least 30 minutes
- The cells are healthy and balanced
Under those conditions, the open-circuit voltage correlates reasonably with SOC and you can use tables like the ones above.
Why SOC from voltage is only an estimate
In real systems, several factors distort the picture:
- Load current – under high load, terminal voltage sags below open-circuit voltage.
- Temperature – cold cells show lower voltage for the same SOC.
- Cell aging – internal resistance increases, causing more sag under load.
- Chemistry – LiFePO4’s flat curve makes 40–80 % SOC almost indistinguishable by voltage alone.
For precise SOC, a BMS or battery monitor with coulomb counting (tracking Ah in and out) is far more accurate than voltage alone.
How Does Charging Voltage Affect Lithium Batteries?
CC-CV charging curve in one look
Most lithium battery chargers use CC-CV:
- Constant Current (CC) – charger pushes a set current (e.g. 0.5 C) while voltage rises.
- Constant Voltage (CV) – once the set voltage is reached, the charger holds that voltage and current tapers down.
- Charge stops when current falls below a threshold (for example 0.05 C).
The lithium charge chart is essentially the mirror image of the discharge curve.
Recommended lithium charge chart by chemistry
Typical per-cell charging voltages:
| Chemistry | Standard Charge V / cell | Common “12 V” Pack Charge V |
|---|---|---|
| Li-ion (NMC/LCO) | 4.20 V | 12.6 V (3 S) |
| LiFePO4 | 3.45–3.65 V | 14.0–14.6 V (4 S) |
| LiPo | 4.20 V | 12.6 V (3 S), 16.8 V (4 S) |
Many LiFePO4 manufacturers recommend slightly lower than 3.65 V/cell (for example 3.45 V) for longer cycle life, sacrificing a little top-end capacity.
Over-voltage, under-voltage and cycle life
- Over-voltage – charging above the recommended CV voltage accelerates degradation and can be unsafe, especially for NMC / LCO and LiPo.
- Under-voltage (over-discharge) – allowing cells to fall below their cut-off can cause capacity loss or internal copper plating.
- 80–90 % daily use window – keeping your lithium battery between roughly 10–90 % SOC (or even 20–80 %) significantly extends lifetime.
For high-value packs (home storage, traction batteries), voltage limits are usually set more conservatively than the absolute chemistry limits on the datasheet.
What Are Safe Voltage Limits for Lithium Batteries?
Daily use vs absolute max voltage
Think in two layers:
- Absolute limits – where the chemistry or BMS fails:
- Li-ion NMC: ~4.25–4.3 V max, ~2.5 V min
- LiFePO4: ~3.65–3.8 V max, ~2.0–2.5 V min
- Recommended operating limits for daily cycling:
- Slightly lower top voltage (e.g. 4.1 V Li-ion, 3.45 V LiFePO4)
- Higher bottom voltage (e.g. 3.0 V Li-ion, 2.8 V LiFePO4)
Your battery will still work outside these softer limits, but long-term capacity loss accelerates.
Storage voltage and long-term health
For long-term storage:
- Li-ion / LiPo: around 40–60 % SOC, typically 3.7–3.85 V per cell
- LiFePO4: more tolerant; many vendors recommend 40–80 % SOC, roughly 3.25–3.35 V per cell
Storing a pack at 100 % charge, especially in a hot environment, is one of the fastest ways to shorten its life.
Temperature effects on safe range
- Cold: voltage sags more, and high-current charging below 0 °C can cause lithium plating.
- Heat: open-circuit voltage rises slightly, and high SOC plus heat accelerates aging.
Good BMS units adjust lithium-ion state of charge limits based on temperature or simply block charging below a certain threshold.
How to Use a Lithium Voltage Chart
Measuring voltage with a multimeter or BMS
- Disconnect heavy loads and chargers; let the battery rest 20–60 minutes.
- Read pack voltage from the BMS, battery monitor, or with a multimeter across the terminals.
- Compare the reading to the appropriate lithium battery voltage chart for your chemistry and series count.
If you have access to individual cell voltages from the BMS, you can also spot imbalances between cells.
Checking SOC in RV, solar and marine systems
For LiFePO4 house banks:
- Above 13.2 V after rest → roughly 80–100 % SOC.
- Around 13.0 V → mid-range, ~50 %.
- Below 12.4 V → time to think about recharging soon.
For NMC-based 12 V lithium packs (3 S):
- 12.6 V → full
- ~11.8–12.0 V → mid-range
- ~10.5 V → near empty
Always cross-check with your lithium battery chart from the manufacturer when available.
Matching chargers, inverters and loads
When specifying equipment:
- Verify the charger’s bulk/absorption voltage matches your chemistry’s charge chart.
- Confirm that the inverter’s low-voltage cut-off suits the battery’s recommended minimum voltage.
- For DC-DC chargers (alternator to lithium), ensure their ignition voltage and cut-off are compatible with the alternator and battery pack.
A mismatch here is the most common cause of “my lithium battery never reaches 100 %” complaints.
Lithium Voltage Troubleshooting Tips
Voltage drops too fast under load
Possible causes:
- Battery is already at low SOC even if the open-circuit voltage looked OK.
- Cables, lugs or busbars are undersized and causing extra voltage drop.
- One or more cells have high internal resistance due to aging.
Check voltage at both the battery terminals and at the load to see where the drop occurs.
Pack voltage normal but capacity is low
If your 12 V lithium pack charges to the correct lithium-ion battery voltage, but runs out quickly:
- Actual capacity may have faded with age.
- BMS may be cutting off early due to one weak cell hitting low-voltage before the others.
- The advertised Ah rating may have been optimistic.
Cell-level data from the BMS is valuable here.
Cells out of balance in a series pack
Signs of imbalance:
- One cell hits high-voltage cut-off before the others during charge.
- The same cell hits low-voltage cut-off first during discharge.
Solutions:
- Allow the pack to remain at the CV stage longer so the BMS can balance.
- If the BMS has an active balancing function, ensure it is enabled.
- In severe cases, manual top-balancing or replacing bad cells may be required.
FAQ: Lithium Battery Voltage & SOC
Q1. Can I use a lead-acid 12 V charger on a lithium battery?
Sometimes, but only if the voltage limits match your lithium charge chart and there is no equalization stage. A dedicated lithium charger is safer.
Q2. Why does my LiFePO4 stay around 13.2 V for so long?
Because LiFePO4 has a flat discharge curve. That voltage corresponds to a wide SOC band, not a single percentage.
Q3. Is it safe to charge a lithium battery to 100 % every day?
Yes, but it will age faster. Limiting daily charge to about 80–90 % SOC (slightly lower charging voltage) can greatly extend life.
Q4. Which chemistry is most forgiving on voltage?
LiFePO4 is generally more tolerant of partial charges and frequent cycling than NMC/LCO or LiPo, which are more sensitive to over-voltage and heat.
Q5. Do I need a lithium battery SOC chart if I have a BMS?
The BMS protects the pack, but a voltage/SOC chart is still useful for understanding readings, verifying charger settings, and diagnosing problems.
Looking for a Reliable LiFePO4 Battery Manufacturer?
If you are comparing lithium battery voltage charts because you are designing a 12 V / 24 V / 48 V system, you don’t just need theory – you need a battery partner who understands voltage windows, BMS protection, and real-world loads.
As a LiFePO4 energy storage manufacturer, Saftec can support you at three levels:
OEM & ODM LiFePO4 Battery Packs
- Custom pack design for 12 V, 24 V, 36 V and 48 V systems
- Cell selection, series/parallel configuration and busbar layout
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- Options for CAN, RS485, UART communication with inverters, chargers and EMS
Whether you need a drop-in 12 V LiFePO4 battery, rack-mount modules or cabinet systems, we can adapt voltage settings and mechanical design to your project.
Engineering Support for Voltage & BMS Settings
- Help interpreting lithium battery voltage & SOC charts for your use case
- Recommendations for charging voltage, cut-off voltage and storage voltage
- Coordination with your charger, inverter or solar controller suppliers
- Assistance with safety margins under different temperatures and load profiles
You don’t need to guess whether 14.4 V or 14.0 V is better for your pack – our engineers can propose a safe window based on your cycle life and runtime targets.
Distributors, Installers and Regional Agents Welcome
If you are a:
- Solar installer or system integrator
- RV / marine / mobility builder
- Battery dealer, distributor or regional agent
Saftec can provide:
- Branded or white-label LiFePO4 batteries
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Share your system voltage, target capacity, load profile and preferred chemistry (LiFePO4) with us, and we can recommend a matching battery solution or co-develop an OEM pack for your market.
