A lithium-ion battery voltage chart shows the relationship between a battery’s voltage and its state of charge (SOC), helping users understand how charged or depleted the battery is. Whether you’re managing a solar setup, powering an electric bike, or troubleshooting your power bank, knowing what different voltage levels mean can help you make smarter, safer decisions.
Here’s an eye-opener: a fully charged 3.7V lithium-ion battery can reach 4.2 volts, while a depleted one can drop to around 3.0 volts. But going too high or too low? That risks damaging the battery or shortening its lifespan.
Best Lithium-Ion Battery for Everyday Use
If you’re wondering what the best lithium-ion batteries are based on practical usage, performance, and reliability, we’ve done the hard work for you. Below are three top-rated lithium-ion batteries that consistently deliver in real-world applications—from electronics and DIY builds to portable power needs.
BENKIA 3.7V 3500mAh Lithium-Ion Battery
Why we picked it: Known for its excellent energy density and consistent discharge rate, it’s a favorite among flashlight enthusiasts and battery pack builders.
Samsung INR18650-30Q 3.6V 3000mAh Lithium-Ion Battery
Why we picked it: Offers a great balance of capacity and high-drain performance, making it ideal for vape mods, e-bikes, and DIY power walls.
JESSY 18650 3.6V 3300mAh Lithium-Ion Battery
Why we picked it: This battery stands out with its higher capacity and reliable cycle life—perfect for long-lasting power banks and solar applications.
What Voltage is a Fully Charged Lithium-Ion Battery?
A fully charged lithium-ion battery typically measures between 4.1V and 4.2V per cell. This voltage range represents 100% state of charge (SOC), and it’s the maximum safe limit for most standard lithium-ion chemistries. Charging beyond this level risks battery damage or safety hazards.
When charging, lithium-ion batteries follow a CC-CV (Constant Current – Constant Voltage) pattern:
- In the constant current phase, voltage rises steadily until it hits around 4.2V.
- At this point, the charger switches to constant voltage, holding it at 4.2V while reducing current until full.
Here’s a simple breakdown of fully charged voltages by lithium-ion type:
- 3.6V nominal cells → 4.2V fully charged
- 3.7V nominal cells → 4.2V fully charged
- 3.2V LiFePO4 cells → 3.6V to 3.65V fully charged (lower max voltage)
Why this matters:
- Devices rely on voltage to estimate battery level.
- Overcharging can trigger thermal runaway—a dangerous chemical reaction.
- Fully charging to 4.2V gives you max run-time, but stopping around 4.1V can extend battery life.
If longevity is more important than run-time, consider charging only up to 4.1V or even 4.0V. It may reduce your use time slightly, but significantly extend battery cycles.
What Voltage is a Dead Lithium-Ion Battery?
A lithium-ion battery is considered “dead” or fully discharged when its voltage drops to around 3.0V per cell or lower. In many cases, devices will automatically shut off when the voltage hits about 3.2V to prevent over-discharge, which can permanently damage the battery.
Here’s a quick breakdown of what a “dead” lithium-ion battery voltage can look like:
- 3.2V–3.0V – Technically discharged, most devices shut down here.
- Below 3.0V – Risk of irreversible capacity loss.
- Below 2.5V – Considered dangerously low. Many chargers will refuse to recharge it for safety reasons.
Why this is important:
- Over-discharging a lithium-ion cell can lead to internal chemical instability.
- If left in a deeply discharged state for long periods, the battery can become unsafe or completely unusable.
- Battery management systems (BMS) in quality devices are designed to cut off discharge at safe levels—usually above 3.0V—to preserve lifespan.
Warning Signs of a “Dead” Battery:
- Your device won’t turn on even after charging.
- Multimeter reads below 3.0V (or nothing at all).
- Charger blinks red or refuses to start charging.
If your battery reads just under 3.0V, you can sometimes revive it with a smart charger that has a recovery mode—but never try to revive swollen or damaged batteries.
What Does Each Voltage Level Mean on a Lithium Ion Battery?
Each voltage level on a lithium-ion battery directly reflects how much charge remains and what condition the battery is in. Understanding this can help you maximize performance, prevent damage, and extend battery life.
Below is a detailed lithium-ion battery voltage chart based on a 3.7V nominal cell, which is the most common type used in devices like laptops, phones, power tools, and solar packs:
Lithium-Ion Battery Voltage Chart (3.7V Nominal Cell)
| Voltage (V) | State of Charge (SOC) | Battery Condition | Remarks |
| 4.20V | 100% | Fully Charged | Max charge level. Stop here for safety. |
| 4.15V | ~95% | Near Full | Slightly lower stress on battery. |
| 4.10V | ~90% | Excellent for daily use | Balances longevity & performance. |
| 4.00V | ~80% | Healthy Charge | Great for extending battery life. |
| 3.90V | ~70% | Moderate Charge | Still plenty of power left. |
| 3.80V | ~60% | Balanced | Often considered the “neutral” voltage. |
| 3.70V | ~50% | Midpoint | Ideal time to recharge for long-term use. |
| 3.60V | ~40% | Slightly Low | Getting closer to low battery warning. |
| 3.50V | ~30% | Low | Device may begin to warn you. |
| 3.40V | ~20% | Very Low | Recharge soon to avoid stress. |
| 3.30V | ~10% | Critical | Device likely shuts off soon. |
| 3.20V | ~5% | Discharged | End of usable charge. |
| 3.00V | 0% | Fully Discharged / “Dead” | Below this risks permanent damage. |
Key Notes:
- Optimal operating range: 3.7V to 4.1V — keeps your battery healthy for longer.
- Avoid frequent full cycles (0% to 100%) unless necessary. This wears out the battery faster.
- Storage tip: Store long-term at 3.7V–3.8V (around 50%) in a cool, dry place.
This voltage chart gives a clear snapshot of battery status and helps prevent overcharging or deep discharge—two of the main causes of lithium-ion degradation.
How Can You Safely Monitor Lithium Ion Battery Voltage?
You can safely monitor lithium-ion battery voltage using tools like digital multimeters, battery management systems (BMS), smart chargers, and battery monitoring apps. Each method offers different levels of precision, safety, and convenience depending on your setup.
Here’s a breakdown of each method and how it works:
Digital Multimeter
A digital multimeter is the most direct and accurate way to check a battery’s voltage.
How it works:
- Set the multimeter to DC volts (V).
- Connect the red probe to the battery’s positive terminal and the black probe to the negative terminal.
- The screen will display the battery’s current voltage.
Why it’s great:
- High accuracy.
- Works on all battery types.
- Doesn’t require the battery to be connected to a device.
Tip: Use a multimeter with auto-ranging for easier reading and safety.
Battery Management System (BMS)
A BMS is typically built into battery packs and protects against overcharging, deep discharge, and overheating.
How it works:
- It constantly monitors voltage, temperature, and current.
- Some BMS units come with Bluetooth or a display to show real-time voltage.
- It cuts off charging or discharging if voltages go beyond safe thresholds.
Why it’s great:
- Automated protection.
- Real-time monitoring.
- Ideal for battery banks, solar systems, or DIY power walls.
Smart Chargers with LCD Displays
Many smart lithium-ion chargers show battery voltage as they charge.
How it works:
- Plug in the battery; the display shows the current voltage and charging status.
- Most stop automatically when 4.2V is reached.
- Some have modes for storage charging (~3.7V) and battery recovery for low-voltage cells.
Why it’s great:
- Easy to use.
- No manual tools required.
- Offers both safety and convenience.
Battery Monitoring Apps or Tools
For built-in or embedded batteries (like in phones or laptops), you can monitor voltage using software tools.
How it works:
- Apps like Battery Monitor, AccuBattery (Android), CoconutBattery (Mac), or HWMonitor (Windows) read system-level battery info.
- These tools display current voltage, charging cycles, and health.
Why it’s great:
- No hardware required.
- Perfect for mobile and computer batteries.
Safety Tips:
- Never probe batteries with damaged terminals or bulges.
- Disconnect from devices before checking manually.
- For multi-cell packs, check each cell separately if possible.
- Always monitor voltage before long-term storage.
Can You Rely on Voltage Alone to Check Lithium-Ion Battery Health?
No, you cannot rely on voltage alone to accurately determine the health of a lithium-ion battery. While voltage gives you a general idea of charge level, it doesn’t reflect internal wear, capacity loss, or the battery’s ability to hold a charge under load.
Why Voltage Isn’t Enough
- State of Charge ≠ State of Health:
A battery might show 4.2V (fully charged), but if it discharges too quickly or can’t deliver sufficient current, it may be degraded. - Voltage Can Plateau:
Lithium-ion voltage remains relatively flat across a large portion of the discharge cycle. That means even unhealthy batteries can show “normal” voltage readings. - Resting vs. Load Voltage:
A battery under load will often drop voltage temporarily. A large drop may indicate high internal resistance, a key sign of aging.
Better Ways to Check Battery Health
To get a full picture, combine voltage checks with the following:
- Capacity Testing:
- Fully charge the battery, then discharge at a known current.
- Time how long it lasts.
- Compare actual mAh output to rated capacity.
- Internal Resistance Measurement:
- Use a battery analyzer or specialized charger (like the Opus BT-C3100).
- Higher internal resistance = poorer battery health.
- Cycle Count Tracking:
- Many smart devices track how many full charge/discharge cycles the battery has gone through.
- Most lithium-ion batteries degrade after 300–500 full cycles.
- Temperature Behavior:
- Overheating during use or charge is a warning sign.
- Healthy batteries stay relatively cool.
Voltage gives you part of the story—mostly about how much charge is present. But if you want to know how much life is left in your battery, combine voltage with performance metrics like capacity, resistance, and cycle count.
Conclusion
Understanding lithium-ion battery voltage is essential for safe usage, maximizing performance, and prolonging battery life. A fully charged cell reads around 4.2V, while a dead one drops to 3.0V or lower. But voltage alone isn’t the full story—true battery health also depends on internal resistance, capacity, and how the battery performs under load.
Whether you’re powering an electric bike, managing a DIY solar power system, or just trying to get more life out of your devices, a lithium-ion voltage chart can be your best friend. Monitoring voltage safely with tools like multimeters, BMS, and smart chargers ensures that you protect your investment and stay safe.
Take time to understand the numbers and apply what you’ve learned in this guide. It’s not just about keeping your batteries alive—it’s about making them last.
Frequently Asked Questions About Lithium-Ion Battery Voltage Chart
Here are some of the most commonly asked questions to help clarify key points and ensure you’re confident when dealing with lithium-ion battery voltages:
What voltage is a fully charged lithium-ion battery?
A fully charged standard lithium-ion cell typically reads 4.2 volts. Charging beyond this can lead to overheating and battery damage, so most chargers automatically stop at this limit.
Is 3.7V a full charge for a lithium-ion battery?
No. 3.7V is the nominal (average) voltage, not the fully charged state. A battery at 3.7V is about 50% charged. For full charge, the voltage should reach 4.2V.
At what voltage is a lithium-ion battery considered dead?
When a lithium-ion battery drops to around 3.0V or below, it is considered fully discharged or “dead.” Prolonged use below this point can cause permanent damage.
Can I use voltage to determine battery health?
Not entirely. Voltage only indicates the current charge level. Battery health also depends on factors like capacity retention, internal resistance, and cycle count.
What’s the safe voltage range for storage?
For long-term storage, keep your battery around 3.7V to 3.8V, which is roughly 40–60% state of charge. This minimizes stress and helps maintain battery health.
How often should I check battery voltage?
It depends on usage. For regular applications, weekly checks are sufficient. For critical systems like solar setups, consider daily monitoring or using a smart BMS.
What happens if I over-discharge a lithium-ion battery?
Over-discharging below 2.5V can lead to chemical instability and permanent damage. In severe cases, the battery may become unsafe to recharge or even unusable.