How low can a lithium battery go?

Last Updated on December 1, 2023 by Jaxon Mike

Lithium-ion batteries have become the most popular type of rechargeable battery for consumer electronics like smartphones, tablets, and laptops. This is due to their high energy density, lack of memory effect, and slow loss of charge when not in use. However, lithium-ion batteries can be damaged if they are discharged too low.

Knowing the limits of how low your lithium battery can safely go is important for maximizing performance and lifespan.

A lithium-ion battery is made up of a positive lithium cobalt oxide cathode, a negative graphite carbon anode, and an electrolyte that allows lithium ions to flow between them.

The movement of the lithium ions back and forth during charge and discharge generates electricity. When the battery is discharged too low, irreversible chemical changes and physical damage can occur that degrade battery performance.

In this article, we’ll cover the key voltage thresholds for lithium batteries, signs that your battery is too low, the dangers of extreme discharge, and best practices for lithium battery care and handling. Following safe voltage limits and usage tips will help your lithium batteries last longer.

Safe Voltage Levels for Lithium Batteries

There are a few key voltage levels to understand when it comes to lithium-ion battery discharge:

Normal Operating Voltage

Lithium-ion batteries are typically rated at 3.6 or 3.7 volts per cell when fully charged. As the battery discharges during normal use, the voltage decreases gradually down to around 3.0 volts. This is considered the normal operating range.

Your device is designed to cut off when the battery voltage reaches around 3.0 volts to protect the battery from over-discharge damage.

Storage Voltage

When lithium-ion batteries will be stored for an extended period without use, they should be discharged to a storage voltage of 3.3-3.4 volts per cell. This reduces stress on the battery during storage. Storing a lithium-ion battery at full charge shortens its lifespan.

Critical Low Voltage Threshold

Discharging below 3.0 volts per cell starts getting into dangerous territory for a lithium battery. The lower the voltage, the more strain on the battery. Most lithium-ion batteries have built in protection circuits that disconnect the battery when the voltage falls below 2.7-2.9 volts per cell to prevent damage.

Damage Voltage Threshold

Allowing a lithium-ion battery to discharge below 2.5 volts per cell will likely lead to permanent damage. At extremely low voltages below 2.0 volts, copper from the negative electrode begins dissolving into the electrolyte, causing internal shorts. The battery will be unusable and unsafe to recharge at this point.

Keeping lithium-ion batteries above 3.0 volts per cell during discharge and never allowing them to go below 2.5 volts is key to maintaining their performance and capacity. Next, let’s look at some signs your battery is running dangerously low.

Signs Your Lithium Battery is Too Low

It’s important to recognize the indicators that your lithium-ion battery has been depleted past its safe operating range. Here are some of the common signs your battery may be too low:

Device Turns Off Abruptly

If your device suddenly turns off when you were just using it, that’s a clue the battery has been drained to the point the protection circuit kicked in to disconnect it. Allowing the battery to discharge this low repeatedly can damage its capacity over time.

Device Restarts Randomly

A device that is exhibiting frequent random restarts or freezing can be a sign of a battery voltage dipping too low. Some devices restart to protect components when the voltage from the battery drops below a certain threshold.

Device Won’t Turn On

If your device won’t power on at all even when plugged into a charger, the battery may be drained extremely low. Leaving lithium-ion batteries in a fully discharged state can be dangerous for the battery’s health. Try leaving it charging for several hours before attempting to turn it on.

Shorter Battery Life

Over time, allowing a lithium-ion battery to discharge too low and remain there for extended periods will degrade its performance and shorten run time per charge. The battery may no longer hold a full charge.

Pay attention to these warning signs that indicate your lithium battery needs recharging or may have already been depleted past safe levels. Running the battery too low too often will accelerate capacity loss. Next, we’ll look at what can go wrong when a lithium battery is drained extremely low.

Dangers of Extremely Low Lithium Batteries

Allowing a lithium-ion battery to discharge too far past the recommended voltage cutoffs can lead to hazardous outcomes. Here are some of the dangers:

Internal Shorts

At voltages under 2.0 volts per cell, the anode electrode can start to dissolve, releasing copper that can deposit on the cathode. This can bridge the electrodes, causing internal shorts and fires.

Thermal Runaway

Completely drained batteries are more susceptible to thermal runaway. This is a feedback loop where rising temperature causes more self-heating, eventually leading to cell rupture or explosion.

Permanent Damage

Lithium batteries discharged below 2.0-2.5 volts per cell often suffer permanent capacity and performance loss. The copper dissolution and other chemical reactions that occur under extremely low voltage conditions damage the cell.

To avoid these issues, lithium-ion batteries should never be discharged below 2.5 volts per cell.

Devices have protection circuits, but it’s still possible to over-discharge if batteries are left in a fully depleted state for weeks or months. Storing lithium-ion batteries long-term at low voltage is especially harmful.

Best Practices for Lithium Battery Care

Following some simple guidelines for charging, storage, and maintenance can help your lithium-ion batteries last longer. Here are some tips:

Avoid Complete Discharge

Try not to let your lithium battery become fully depleted whenever possible. Discharging below 3.0 volts per cell adds strain. If the battery does become completely dead, recharge it as soon as possible. Leaving it discharged causes more damage.

Store Batteries Properly

When storing lithium-ion batteries long-term, discharge them to around 50% charge, or 3.6-3.7 volts per cell. This reduces stress. Store them in a cool, dry place around room temperature. Higher temperatures accelerate capacity loss over time.

Replace Aging Batteries

Lithium-ion batteries gradually wear out as they age, even with proper care. Battery capacity naturally degrades over time. Plan on replacing lithium batteries after 2-3 years or 300-500 charge cycles for optimal performance.

Use Quality Chargers

Avoid using third-party chargers and stick with the charger designed for your device. Low-quality chargers can overcharge batteries, applying excess voltage and heat that degrades the battery. Use chargers from reputable brands.

Don’t Overcharge

Avoid leaving lithium batteries plugged into a charger for prolonged periods after they are fully charged. Once fully charged, continuing to apply a charge causes strain and accelerates capacity loss over time.

Discharge and Recharge Monthly

To keep the electrons moving through the battery, it’s good practice to discharge your lithium battery to 50% and recharge once per month if the device isn’t being used regularly. This cycling maintains the battery’s health.

Avoid High Temperatures

Exposure to high temperatures also accelerates the aging process. Don’t leave your device or battery in hot environments like a hot car. High temperatures can cause faster capacity degradation.

Use the Battery

Lithium-ion batteries age faster when left unused for long periods compared to regular use. The optimal health is maintained by moderate, regular use rather than leaving it idle.

By following these battery care best practices, you can maximize the lifespan and performance of your lithium-ion batteries and keep them operating safely.

FAQs

What is the normal voltage range for lithium-ion batteries during use?

Between 3.0-3.7 volts per cell is considered the normal operating voltage range. Voltage drops from about 3.7 volts when fully charged down to around 3.0 volts before the protection circuit cuts off discharge.

Can lithium batteries explode if discharged too low?

Extremely discharged lithium batteries can potentially catch fire or explode due to internal shorts or thermal runaway. However, built-in protection circuits prevent batteries from being drained this low during normal use.

How can I recover a lithium battery that won’t charge?

If a lithium battery won’t charge, it may have been discharged too low, causing permanent damage. Leaving it in the charger for several hours may revive it, but the capacity may be reduced. If it still won’t charge, the battery likely needs to be replaced.

What should the voltage be when storing lithium batteries?

For long-term storage, lithium batteries should be discharged to around 3.6-3.7 volts per cell, which is about 40-50% charge capacity. Storing fully charged shortens battery lifespan.

Does cold temperature damage lithium battery capacity?

Cold temperatures below freezing can temporarily reduce battery capacity. But as long as the battery warms back to room temperature, no permanent damage is typically done. High heat is more damaging than cold.

Conclusion

In summary, lithium-ion batteries contain risky chemicals and can be damaged if discharged too low. But understanding the critical voltage thresholds and adhering to usage and storage guidelines will keep your lithium batteries in optimal health.

Try to keep lithium-ion batteries charged between 30-80% capacity for everyday use, and never allow them to drop below 2.5 volts per cell. Store batteries around 50% charge and avoid high temperatures or overcharging.

With proper care and handling, lithium batteries can deliver hundreds of reliable charge cycles. Monitoring your battery voltage and replacing aging batteries will allow you to safely harness the power of lithium-ion for years to come.