What is the Self Discharge Rate of Li-ion Battery?

A Li-ion battery slowly loses charge when it is not in use. This is called the self discharge rate. It happens even when the battery is not connected to a device.

This rate affects storage time, shelf life, backup power, and product reliability. A battery with low self discharge keeps more usable power during storage.

Key takeaways

• The self discharge rate shows how much charge a battery loses during storage.
• The self discharge rate of lithium ion battery cells is usually lower than NiMH and lead-acid batteries.
• Heat, battery age, state of charge, chemistry, and cell quality affect self discharge.
• Most Li-ion batteries should be stored at 40%–60% charge.
• A self discharge test helps find weak or unstable cells before delivery.

Part 1. What is li-ion battery self discharge rate?

The li ion battery self discharge rate means the charge loss of a battery when it is stored with no load. It is often shown as a percentage per month.

For example, if a battery loses 2% of its charge in one month, its self discharge rate is about 2% per month.

Self discharge is different from the normal battery discharge rate. Normal discharge happens when the battery powers a device. Self discharge happens when the battery is resting.

You may also see these terms in battery datasheets:

• Li ion self discharge rate
• Battery self discharge rate
• Self-discharge loss
• Capacity retention after storage
• Open circuit voltage drop

For 18650 cells, the term 18650 discharge rate can mean two things. It may mean the storage self discharge rate. It may also mean the current output during use. These are not the same.

Part 2. Typical self discharge rate of different battery types

Battery chemistry has a strong effect on self discharge. The table below shows common reference values at room temperature. Actual data depends on cell design, age, charge level, and storage condition.

Li-ion and LiFePO4 batteries are common in modern products because they offer low self-discharge, high energy density, and good storage performance.

Part 3. How temperature affects self discharge rate?

Temperature is one of the biggest factors. High temperature speeds up chemical reactions inside the battery. This increases self discharge. It also makes the battery age faster.

For many Li-ion batteries, 15°C to 25°C is a good storage range. This helps reduce charge loss and slows down aging.

Cold storage can slow self discharge. But very low temperature is not always safe for charging or discharging. Always follow the battery maker’s instructions.

Temperature and lithium battery storage

For better lithium battery storage, avoid heat, high humidity, and long-term full charge. This is important for LiPo batteries used in drones, RC models, wearables, and portable devices.

Part 4. Main factors that affect li-ion battery self discharge

1. Battery chemistry

Different battery chemistries have different self discharge rates. Li-ion, LiPo, and LiFePO4 batteries are all lithium batteries. But their materials are not the same.

The LiFePO4 self discharge rate is usually low. LiFePO4 chemistry is stable and safe for storage. NMC and LiCoO2 cells can also have low self discharge if the cell design and materials are well controlled.

2. Electrolyte quality

The electrolyte helps lithium ions move inside the battery. Poor electrolyte quality can cause side reactions. These reactions use active lithium and increase self discharge.

Good electrolyte and additives help form a stable internal layer. This can reduce charge loss during storage.

3. Electrode interface

The electrode interface is the contact area between the electrode and electrolyte. A stable interface reduces unwanted reactions.

Good coating, clean materials, and tight process control can help lower the li ion battery self discharge rate.

4. State of charge during storage

A battery stored at full charge usually ages faster. A battery stored at very low charge may enter over-discharge after a long time.

For many Li-ion and LiPo batteries, 40%–60% charge is better for long-term storage.

Self discharge is different from battery depth of discharge. Depth of discharge means how much power is used during operation. Self discharge means charge loss during storage.

5. Battery age

Old batteries often lose charge faster. Their internal resistance may rise. Their electrode and electrolyte may also degrade.

This can increase the battery self discharge rate and reduce usable capacity.

6. Cell quality

Dust, moisture, metal particles, poor coating, and weak sealing can increase self discharge. These problems may cause small internal leakage paths.

This is why strict production control is important for long shelf life and stable battery performance.

Part 5. How manufacturers test self discharge rate?

A self discharge test checks how much voltage or capacity a battery loses after storage. It helps find cells with high leakage, unstable chemistry, or hidden defects.

Test methods may vary by cell type and project needs. Many battery makers also follow recognized standards, such as IEC 61960 for rechargeable lithium cells and batteries. Transport tests may also refer to the UN Manual of Tests and Criteria.

Common self discharge test steps

1. Charge the battery to the required level.
2. Rest the battery in a controlled room.
3. Measure open circuit voltage.
4. Compare the voltage drop.
5. Run a capacity test if needed.
6. Remove abnormal cells before shipment.

A simple capacity-based formula is:

Self discharge rate = (Initial capacity – Remaining capacity) ÷ Initial capacity × 100%

Resting voltage method

This method is fast. The battery is charged and stored for a set time. Then the voltage is measured. A large voltage drop may show high self discharge.

This method is useful for batch screening. But voltage alone may not show the full capacity loss.

Capacity test method

This method is more accurate. The battery is charged and tested for capacity. After storage, it is tested again. The capacity loss shows the real self discharge.

Coulomb counting method

Coulomb counting uses a BMS to track charge movement. It can estimate charge loss during rest. This method is useful for smart battery packs.

Internal resistance test

Internal resistance can rise when a battery ages. This does not directly equal self discharge. But it helps show battery health.

Accelerated aging test

This test uses controlled heat and storage time. It helps predict long-term storage life and battery reliability.

Part 6. How ufine controls li-ion battery self discharge rate?

Ufine Battery controls materials, production steps, and testing data. This helps reduce abnormal self discharge in custom Li-ion, LiPo, and LiFePO4 battery projects.

Controlled production environment

Humidity and temperature must be controlled during battery production. Too much moisture can cause side reactions and gas. A stable production room helps reduce defects.

High-quality raw materials

Battery materials affect self discharge. These include cathode materials, anode materials, separators, electrolytes, tabs, and packaging materials.

Cleaner and more stable materials help lower the self discharge rate.

Strict quality control

Ufine Battery checks voltage, capacity, internal resistance, charge data, discharge data, and storage data.

Cells with abnormal self discharge can be removed before pack assembly. This improves safety and consistency.

Formation and aging treatment

Formation helps build a stable internal layer inside the battery. Aging allows the cell to rest after formation.

This process helps find unstable cells before delivery.

Automated testing system

Ufine Battery uses an Automated Testing System for batch testing. The system records test data and reduces manual errors.

This makes self-discharge screening faster and more stable. It also helps each battery meet project needs before shipment.

Part 7. How to reduce battery self discharge during storage?

Good storage can reduce charge loss and extend battery life. This is important for factories, distributors, device brands, and end users.

Store batteries at partial charge

Do not store Li-ion batteries at full charge for a long time. A 40%–60% charge level is better for long storage.

Keep batteries cool and dry

Avoid hot warehouses, cars, direct sunlight, and humid rooms. Heat can increase the lithium battery discharge rate during storage.

Check voltage during long storage

Check battery voltage from time to time. Recharge the battery if the voltage becomes too low. This helps prevent over-discharge.

Use the correct charger

Use a charger that matches the battery chemistry and voltage. A wrong charger can damage the battery and increase safety risk.

Avoid mixing old and new cells

Battery pack cells should be matched. Key data includes capacity, voltage, internal resistance, and self discharge. Poor matching can cause imbalance and shorter pack life.

Part 8. Self discharge rate in real applications

Self discharge matters when a product is stored, shipped, or used only sometimes. It affects whether the device still has power after weeks or months of rest.

Part 9. FAQs about li-ion battery self discharge rate