Lithium batteries are widely used in electronics, EVs, and energy storage, but self-discharge remains a common concern. The passage explains lithium battery self discharge rate, detailing internal mechanisms, external influences, calculation methods, and strategies to reduce energy loss. It also provides practical tips for storage, BMS design, and maintenance, helping you maximize battery lifespan, performance, and reliability. Learn how to store and manage lithium batteries efficiently and prevent unexpected capacity loss.
Main content:
- What is Lithium Battery Self Discharge Rate?
- Typical Li Ion Self Discharge Rate
- Why Lithium Batteries Self-Discharge
- How to Calculate Lithium Battery Self Discharge Rate
- Normal vs. Abnormal Self-Discharge
- How to Reduce Self Discharge Rate of Lithium Ion Battery
- Conclusion
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FAQs
- What is the self-discharge rate of an 18650 lithium-ion battery?
- What is the typical self-discharge rate of an AGM battery?
- How fast does a car battery self-discharge when not in use?
- What is the self-discharge rate of a standard lead-acid battery?
- Do LiFePO4 batteries self-discharge when stored?
- Is keeping lithium batteries fully charged harmful?
- What does 80% SOC represent in lithium batteries?
What is Lithium Battery Self Discharge Rate?
Self-discharge refers to the phenomenon where a battery gradually loses energy over time even when not connected to any load. For lithium-ion batteries, self-discharge mainly comes from natural chemical reactions in internal materials, changes in electrode interface films, electrolyte reactions, and minor leakage currents, all of which are fundamental factors for the lithium battery self discharge rate. Although this phenomenon cannot be completely avoided, modern lithium batteries have greatly reduced this rate through materials and manufacturing processes, making them more stable during long-term storage.
Typical Li Ion Self Discharge Rate
Lithium batteries are known for their relatively low lithium battery self discharge rate, usually only 1–3% per month at room temperature. In comparison, lead-acid batteries may self-discharge 4–6% per month, especially in high temperatures; NiMH batteries typically lose 10–15% per month, and NiCd batteries also discharge relatively fast.
Therefore, the li ion self discharge rate is clearly better than traditional battery systems, making lithium batteries more suitable for long-term storage while maintaining high usable battery capacity. This is one reason modern electronics and energy storage devices widely use lithium-ion battery technology.
Comparison of Self-Discharge Rates of Different Battery Chemistries
This table presents our in-house laboratory test data, summarizing the typical monthly self-discharge rates at room temperature (20–25°C), high-temperature performance, underlying causative factors, recommended storage conditions, and the compound-calculated remaining capacity after 12 months.
| Battery Type | Typical Self-Discharge Rate (per month, 25°C) |
At High Temperature (~40°C) | Causes / Characteristics | Storage Recommendations | Estimated Remaining Capacity After 12 Months |
|---|---|---|---|---|---|
| Lithium-ion (Li-ion, NMC / NCA) | 1–3% / month | Increases to ~2–6% / month | Self-discharge driven by electrolyte oxidation and minor parasitic reactions; BMS adds slight standby drain. | Store at 40–60% SOC, cool and dry place; avoid long-term high temperature and full charge. | 1%/mo → ~88.6%; 3%/mo → ~69.4% |
| LiFePO₄ (LFP) | 0.5–2% / month | ~1–4% / month | Very stable chemistry; fewer side reactions; lower temperature sensitivity compared to NMC. | Store at 40–70% SOC; keep away from extreme heat; check every 3–6 months. | 0.5%/mo → ~94.2%; 2%/mo → ~78.5% |
| Solid-State Lithium | 0.5–2% / month | Depends on electrolyte; often more heat-tolerant | Reduced electrolyte side reactions, but varies widely by design and interface engineering. | Store at moderate SOC in cool conditions per manufacturer guidelines. | ~78–94% (depends on chemistry) |
| Lithium Polymer (Li-Po) | 1–3% / month | ~2–6% / month | Similar to Li-ion; uses polymer-based electrolyte packs; similar parasitic reactions. | Avoid full-charge storage; keep at 40–60% SOC in a cool area. | 1%/mo → ~88.6%; 3%/mo → ~69.4% |
| Lead-Acid (Flooded) | 4–6% / month | ~8–12% / month | Plate corrosion and sulfation drive self-discharge; accelerated by high temperature. | Keep fully charged; periodic maintenance charging; avoid heat. | 5%/mo → ~54.0% |
| VRLA / AGM / Gel (Sealed Lead-Acid) | 3–6% / month | ~6–10% / month | Gas recombination limited; heat accelerates degradation and water loss internally. | Charge regularly; keep cool; avoid prolonged storage while partially discharged. | 4%/mo → ~61.3% |
| NiMH | 10–15% / month | 20%+ / month | Hydrogen recombination reactions and internal leakage currents are high; sensitive to heat. | Store at low temperature (not freezing) with partial charge; cycle periodically. | 12%/mo → ~21.6% |
| NiCd | 10–15% / month | Higher under heat | High internal leakage and memory effect; older technology with relatively fast self-discharge. | Store at low SOC; periodic full discharge/charge cycles recommended. | 12%/mo → ~21.6% |
| Alkaline (Primary) | 0.1–0.3% / month | Slight increase, reduced shelf life | Very low internal reactions due to sealed primary chemistry. | Store in cool, dry conditions; avoid heat. | 0.2%/mo → ~97.0% |
| Zinc-Air (Primary) | Near zero when sealed; very high once exposed to air | Degrades rapidly at high temperature | Relies on oxygen from air; once activated, self-discharge becomes extremely fast. | Keep sealed until use; after activation, expect rapid depletion. | Not suitable for 12-month estimation |
Why Lithium Batteries Self-Discharge
Lithium battery self-discharge is caused by a combination of internal and external factors. Internal factors include micro-short circuits, SEI growth, side reactions of electrolyte and electrode, electrode side reactions, and BMS quiescent current. External factors include moisture, high temperature, high SOC, and unstable electrolyte at high voltage. Understanding these factors helps optimize storage and use, reducing the self discharge rate of lithium ion battery and extending battery life.
Internal Mechanisms
Micro-Short Circuits
Lithium batteries may have tiny internal short circuits, called micro-shorts. These channels usually result from residual impurities during manufacturing, material defects, moisture intrusion, or aging from long-term use. Micro-shorts generate very small continuous leakage currents, causing gradual discharge even when the battery is idle.
SEI Growth and Repair
The solid electrolyte interphase (SEI) on the anode surface protects battery stability but is not completely stable. Over time, SEI experiences slight cracking and self-repair, consuming a small amount of lithium ions. This contributes significantly to the lithium battery self discharge rate.
Electrolyte Side Reactions
Organic solvents in the electrolyte may react with electrodes under idle conditions, especially in the presence of impurities or trace moisture. These side reactions slowly consume reversible lithium, causing the li ion self discharge rate. While slow, cumulative effects can noticeably reduce battery capacity over time.
Electrode Side Reactions
The electrodes themselves may undergo chemical reactions. Lithium-rich anodes, slight dissolution of cathode materials, and surface contact with electrolyte all produce side reactions during storage. These reactions slowly consume energy and are a core reason for self discharge rate of lithium ion battery.
BMS Quiescent Current
Smart lithium batteries usually have a BMS to monitor voltage, temperature, and safety. Even when idle, the BMS consumes a very small current. Though minimal per hour, over long periods, this contributes to gradual energy loss and increases self-discharge.
External Factors
Moisture Effects
Moisture is one of the most critical external factors accelerating self-discharge. Water entering the battery can damage the electrolyte, corrode the SEI, and potentially cause internal short circuits. This significantly increases lithium battery self discharge rate and may even trigger thermal runaway, making moisture control essential for storage and transport.
Temperature Influence
High temperatures accelerate internal chemical reactions, destabilize SEI, increase electrolyte activity, and speed up cathode dissolution, raising self-discharge rates. Typically, every 10°C rise doubles the self discharge rate of lithium ion battery, highlighting the importance of temperature control.
State of Charge
SOC greatly affects self-discharge. High SOC (near full charge) accelerates side reactions due to lithium-rich anodes, leading to faster self-discharge. Storing at moderate SOC (40–80%) reduces battery stress and slows discharge, helping extend lithium battery life.
Electrolyte Decomposition and High Voltage
At high voltage, electrolyte decomposition accelerates and electrode materials may undergo minor structural changes. These reactions continuously consume reversible lithium ions, causing natural energy loss and forming a key chemical mechanism for lithium battery self discharge rate.
How to Calculate Lithium Battery Self Discharge Rate
Based on Capacity Loss
Lithium battery self-discharge can be calculated by capacity loss, which compares the available capacity after idle time to the initial capacity. For example, a 10Ah battery remaining 9.8Ah after 30 days has a lithium battery self discharge rate of about 2% per month. This method is intuitive and suitable for evaluating real-world performance degradation.
Based on Open Circuit Voltage
Another common method is to estimate self-discharge using the battery’s OCV drop. As the battery sits idle, OCV decreases with capacity loss, allowing calculation of the self discharge rate of lithium ion battery. This method is especially useful for batteries where capacity cannot be directly measured and quickly reflects energy loss trends.
K-Value Method
The K-Value method uses an empirical formula combining capacity, temperature, and storage time to calculate li ion self discharge rate. It is often applied in batch management and quality testing, predicting self-discharge under various conditions and guiding storage and maintenance.
Normal vs. Abnormal Self-Discharge
Normal Self-Discharge
Normal self-discharge refers to energy loss occurring naturally under proper conditions according to battery chemistry and environment. For lithium-ion batteries, this is usually 1–3% per month, a reasonable lithium battery self discharge rate. Normal self-discharge does not affect safety and only requires proper storage.
Abnormal Self-Discharge
Abnormal self-discharge occurs when energy loss exceeds normal ranges, potentially 5% per month or higher. This is usually caused by internal defects (micro-shorts, SEI damage, electrolyte contamination) or external factors (high temperature, moisture). Abnormal self-discharge accelerates capacity degradation and may increase safety risks, requiring timely inspection and mitigation.
How to Reduce Self Discharge Rate of Lithium Ion Battery
Reducing lithium battery self discharge rate requires controlling storage conditions (temperature, humidity), optimizing BMS design, applying proper charge strategies, and performing regular inspections. Comprehensive management extends battery life.
Storage Environment
The lithium battery self discharge rate is closely related to storage conditions. To reduce self-discharge, store batteries around 25°C in dry, ventilated areas, avoiding high temperature and humidity. High temperatures accelerate electrolyte decomposition and side reactions, while moisture may cause internal micro-shorts. Also, avoid storing fully charged batteries for long periods, as high SOC increases side reactions and accelerates energy loss.
BMS Design
A high-quality BMS can effectively control the self discharge rate of lithium ion battery. Low-voltage cutoff (LVC) prevents deep discharge damage, overcharge protection avoids high-voltage side reactions, and balancing functions maintain stable voltage among cells, reducing self-discharge.
Pre-Storage Charging Strategy
Do not fully charge lithium-ion batteries before long-term storage. Optimal storage SOC is 40–60%, which lowers li ion self discharge rate and protects battery life. Excessively high SOC accelerates anode side reactions, while too low SOC risks over-discharge and capacity loss.
Regular Inspection
For long-term stored batteries, check capacity and perform necessary charge/discharge maintenance every 3–6 months. Regular inspections detect abnormal self-discharge early and allow corrective measures. This practice effectively controls lithium battery self discharge rate, extends battery life, and ensures good performance when reused.
Conclusion
Understanding lithium battery self discharge rate empowers you to store, maintain, and use batteries more effectively. By controlling temperature, SOC, and BMS settings, you can extend lifespan and reliability. Explore our website for more expert guidance, practical tips, and in-depth analyses to optimize battery performance and keep your devices running longer with confidence.
FAQs
What is the self-discharge rate of an 18650 lithium-ion battery?
An 18650 lithium-ion cell typically self-discharges about 1–3% per month at room temperature. High temperatures, aging, and high SOC can slightly increase the rate.
What is the typical self-discharge rate of an AGM battery?
AGM battery self discharge rate is usually 2–4% per month at 25°C. Their low self-discharge makes them suitable for standby use, though heat can accelerate the loss.
How fast does a car battery self-discharge when not in use?
A typical automotive lead-acid battery self-discharges 3–5% per month, depending on temperature and battery age. Parasitic loads in vehicles may increase the effective discharge rate.
What is the self-discharge rate of a standard lead-acid battery?
Standard flooded lead-acid batteries self-discharge around 4–6% per month. Heat, sulfation, and poor maintenance can raise this rate, reducing available capacity during storage.
Do LiFePO4 batteries self-discharge when stored?
Yes, LiFePO4 batteries self-discharge very slowly, typically 1–2% per month. Their stable chemistry and strong SEI layer give them one of the lowest self-discharge rates among lithium batteries.
Is keeping lithium batteries fully charged harmful?
Yes, storing lithium batteries at 100% SOC accelerates aging, increases side reactions, and raises self-discharge. Keeping them at 40–80% helps extend cycle life and stability.
What does 80% SOC represent in lithium batteries?
80% SOC means the battery’s State of Charge is at 80% of its total capacity. Operating within 30–80% SOC helps reduce stress, heat, and long-term degradation.
