Lithium‑battery reliability testing encompasses a wide variety of methods, designed to evaluate performance, safety, and service life under diverse intended operating conditions, misuse scenarios, and environmental stresses. These tests typically vary depending on the application domain—such as consumer electronics, electric vehicles, or energy‑storage systems—and the applicable standards, including GB/T, IEC, UL, UN, SAE, ISO, and others. The main categories include:
I. Safety and Reliability Testing (with a focus on assessing the battery’s safety limits under extreme or abusive conditions)
Electrical Abuse Test:
Overcharge test: Charge the battery to a voltage far exceeding its rated maximum (typically 1.5 times or higher), and monitor for ignition, explosion, or leakage.
Over-discharge test: The battery is discharged to a voltage far below its rated cut-off voltage—potentially even to reverse‑charge—and assessed for leakage, an increased risk of internal short circuits, or irreversible damage.
External short-circuit test: With the battery fully charged, a low-resistance conductor is used to bridge the positive and negative terminals, simulating an accidental short circuit, while monitoring temperature rise and whether fire or explosion occurs.
Forced Discharge Test: A reverse forced discharge is applied to individual cells within the battery pack, simulating the scenario where, upon failure of one cell, the remaining cells attempt to recharge it.
Mechanical Abuse Test:
Crush Test: A specially shaped indenter—such as a cylinder or flat plate—is used to compress the battery at a specified rate until a predetermined level of deformation or pressure is reached, simulating vehicle collision or severe crushing conditions to assess whether ignition or explosion occurs.
Needle‑penetration test: A steel needle of a specified diameter (e.g., 3 mm or 8 mm) is driven into the battery at a prescribed speed—typically through the thickest part or a designated location—to simulate an internal short circuit and assess whether ignition or explosion occurs. (Note: Certain newer standards, such as GB 38031‑2020, have removed this requirement for electric‑vehicle batteries, but it remains an important evaluation method.)
Impact Testing: Subject the battery to high‑magnitude mechanical shocks (e.g., several tens of g) using half‑sine waves, post‑peak sawtooth waves, and other waveforms, thereby simulating severe collisions or drop impacts.
Drop test: The battery is dropped from various heights (e.g., 1 m, 1.5 m) in different orientations onto a hard surface (e.g., concrete).
Vibration Testing: Simulates vibration environments encountered during transportation or operation—such as random vibration and sinusoidal sweep tests—to assess structural integrity, connection reliability, and whether prolonged vibration leads to performance degradation or failure.
Tumble Test: The battery is subjected to continuous tumbling about multiple axes (e.g., 10 cycles within 6 hours) to assess its safety under non‑normal operating conditions.
Thermal Abuse Test:
Thermal shock testing: The battery is subjected to rapid cycling between extreme high temperatures (e.g., +85°C/+130°C) and extreme low temperatures (e.g., −40°C) to evaluate material durability and seal integrity.
High-Temperature Storage Test: A fully charged battery is stored for an extended period (from several days to several weeks) at a temperature exceeding its normal upper operating limit (e.g., 60°C, 85°C, 130°C), and capacity fade, internal resistance increase, leakage, and the risk of fire or explosion are evaluated.
Thermal testing: Place the battery in a high-temperature chamber, ramp up to the target temperature (e.g., 130°C, 150°C) at a specified rate, and maintain that temperature for a set duration, while monitoring for thermal runaway behavior.
Thermal Runaway Propagation Test: Primarily conducted on battery modules or packs, this test artificially triggers thermal runaway in a single cell—via heating or puncture—and observes whether the phenomenon propagates to adjacent cells or the entire system, thereby evaluating the system’s thermal management design and containment capabilities. This test is a mandatory requirement for electric vehicle batteries.
Environmental Abuse Test:
Low-Pressure (Altitude Simulation) Test: Simulates the low-pressure conditions at high altitudes (e.g., 15,240 meters/11.6 kPa) or in air transport environments to assess whether leakage, swelling, or ignition and explosion occur.
Burn‑in test: The battery or battery pack is subjected to direct external flame exposure—such as a gasoline flame or a propane flame—for a specified duration to evaluate its fire resistance and whether it may exacerbate thermal runaway.
II. Environmental Adaptability and Reliability Testing (to evaluate the battery’s performance and durability under its intended operating conditions)
Temperature cycling test: Conduct multiple cycles (ranging from dozens to hundreds) within a specified temperature range (e.g., −40°C to +85°C) to simulate diurnal, seasonal, or operational environmental variations, and assess capacity fade, internal resistance changes, sealing integrity, and material fatigue.
High-Temperature, High-Humidity Storage/Operational Testing: Store the device or subject it to charge–discharge cycling under elevated temperature (e.g., 40°C, 55°C) and high relative humidity (e.g., 85%, 95% RH) conditions to evaluate electrolyte stability, interfacial side reactions, corrosion, leakage current, and capacity retention.
Low-Temperature Storage/Operational Testing: Store or perform charge–discharge cycles at extremely low temperatures (e.g., −20°C, −30°C, −40°C), typically at low C-rates, to evaluate low-temperature start-up capability, capacity retention, internal resistance increase, and the risk of lithium plating.
Salt Spray Test: This test simulates coastal or salt‑containing environments (e.g., spraying with a 5% NaCl solution) and primarily evaluates the corrosion resistance of battery pack housings, connectors, and metal components. Since individual cells are typically sealed, this test is more focused on the system level.
Dust and water resistance testing: Conduct tests in accordance with IP ratings (e.g., IP67, IP6K9K) to evaluate the sealing and protection performance of the battery pack housing.
III. Electrical Performance and Life‑Reliability Testing (to evaluate battery performance degradation and service life under normal operating conditions)
Cycle life testing: Under specified charge–discharge conditions (temperature, C-rate, cut-off voltage, and SOC range), the battery is subjected to repeated charge–discharge cycles until its capacity declines to a predefined threshold (e.g., 80% of the initial capacity). The number of cycles is recorded. This is a core test for evaluating the battery’s service life.
Calendar Life Testing: The battery is stored for extended periods (from several months to several years) at various state-of-charge (SOC) levels (e.g., 50%, 100%) and temperatures, with periodic assessments of capacity and internal resistance degradation. This simulates the aging of the battery during storage.
Rate performance testing: Evaluates the battery’s capacity retention, voltage plateau, and thermal‑rise characteristics under various charge–discharge currents (rates).
Self‑discharge test: Measures the capacity loss or voltage drop of a battery after it has been stored under open‑circuit conditions for a specified period (e.g., 7 days, 28 days), to evaluate its storage performance and the potential for internal micro‑short circuits.
Internal Resistance Testing: Measures the battery’s DC or AC internal resistance at various states of charge (SOC) and temperatures; an increase in internal resistance is a key indicator of aging.
Capacity Test/Energy Test: Measures the battery’s actual discharge capacity and energy under standard conditions.
Operational-condition simulation testing: Batteries are tested using real-world or simulated application load profiles—such as electric‑vehicle driving cycles or energy‑storage charge–discharge curves—to evaluate performance and lifespan under conditions that closely mirror actual usage scenarios.
Storage Recovery Test: After the battery has aged under specific conditions (such as high-temperature storage), it undergoes several charge–discharge cycles under standard conditions to assess the extent of its performance recovery.
IV. Other Reliability Tests
Insulation Resistance Test: This test evaluates the insulation performance between the internal circuits of the battery pack (module) and its enclosure or ground—particularly critical for high-voltage systems.
Dielectric Strength Test: Evaluates the voltage‑withstand capability of high‑voltage components in the battery pack, such as DC dielectric strength and AC dielectric strength.
EMC Testing: Electromagnetic compatibility testing that evaluates the battery pack’s susceptibility to external electromagnetic interference and its own immunity to such interference at the system level.
Noise and Vibration Testing: Evaluates the noise and vibration levels generated by the battery pack during operation, at the system level—particularly when the cooling system is active.
Durability Testing: Simulates mechanical stresses encountered during long-term use, such as the number of connector mating cycles and the number of wire harness bends (at the system level).
Which trials to select depends on
Battery application scenarios—such as consumer electronics, electric vehicles, energy storage, power tools, and aerospace—vary significantly in their requirements.
Target Markets and Regulatory Requirements: Different countries and regions have their own mandatory certification standards, such as China’s CCC/Compulsory Inspection, the European Union’s CE, North America’s UL/UN 38.3/DOT, and international standards like IEC, among others.
Customer’s specific requirements: OEM manufacturers typically have their own, more stringent corporate standards.
Requirements during the R&D phase: The R&D phase may involve more comprehensive exploratory testing, while the mass-production phase focuses on validation testing to ensure compliance with standards and customer requirements.
Summary: Reliability testing of lithium batteries constitutes a large and complex framework, encompassing multiple dimensions such as safety, environmental conditions, electrical performance, and service life. By systematically conducting these tests, it is possible to comprehensively evaluate the quality, reliability, and safety of lithium batteries, thereby ensuring their successful deployment across diverse application scenarios. When designing test plans, it is essential to refer to applicable national standards, international standards, and industry specifications.