Comprehensive Analysis of Lumen Maintenance Test Method for LED Luminaires and Aging Life Test System

Abstract​
This article focuses on the lumen maintenance test method for LED products, aiming to provide a detailed introduction to the testing principles, procedures, and practical applications of the LISUN LEDLM-84PL LED Optical Aging Test Instrument. By elaborating on relevant industry standards, system features, and test results, it offers a comprehensive understanding of how to accurately evaluate the lumen maintenance and aging life of LED luminaires. This study serves as a valuable reference for manufacturers, researchers, and quality control personnel in the LED lighting industry.​

1. Introduction: The Importance of Lumen Maintenance Test Method​
In the modern lighting industry, LED (Light-Emitting Diode) products have become increasingly popular due to their energy efficiency, long lifespan, and environmental friendliness. However, the performance of LEDs, especially their lumen maintenance ability, which refers to the preservation of light output over time, is crucial for ensuring user satisfaction and product reliability. The lumen maintenance test method is a systematic approach used to measure how the light output of LED luminaires or modules degrades as they age under different operating conditions.​

Unlike traditional lighting sources that often fail suddenly, LEDs experience a gradual decline in lumen output. This makes it essential to have standardized and reliable test methods to predict their long-term performance. The results of lumen maintenance tests can help manufacturers optimize product designs, improve production processes, and provide consumers with accurate information about the lifespan of LED products. Key indicators such as L70 (the time when the lumen output drops to 70% of its initial value) and L50 (the time when the lumen output drops to 50% of its initial value) are widely used in the industry to assess the aging life of LEDs.​

The LISUN LEDLM-84PL LED Optical Aging Test Instrument is designed to meet the requirements of lumen maintenance testing for LED luminaires. It provides a comprehensive solution for conducting accurate and efficient tests, in line with international industry standards. This article will explore in detail the lumen maintenance test method implemented by the LEDLM-84PL system, including its technical features, testing procedures, and practical applications.​

2. Industry Standards for Lumen Maintenance Testing​

The lumen maintenance test method is mainly guided by a series of standards established by the Illuminating Engineering Society (IES). These standards ensure consistency and comparability in testing results across different manufacturers and laboratories.​

2.1 IES LM-84​

The IES LM-84 standard, titled “Measuring Optical Radiation Maintenance of LED Lamps, Light Engines, and Luminaires,” specifically focuses on the procedures for testing the optical radiation maintenance of LED products over time. It clearly defines the environmental conditions, such as temperature and humidity, during the test, as well as the power supply requirements and data recording intervals. By following the LM-84 standard, manufacturers can accurately measure the changes in the light output of LED luminaires during their operation.​

2.2 IES LM-80​

The IES LM-80 standard is centered around “LED Lumen Maintenance and Aging Life Test.” It is mainly applicable to single LEDs or LED modules. This standard specifies the testing protocols for lumen maintenance under specific temperature and drive current conditions. It helps in understanding the performance degradation characteristics of individual LED components, which is fundamental for the design and production of high-quality LED products.​

2.3 IES TM-28 and TM-21​

IES TM-28 and TM-21 are technical memoranda that provide mathematical models for predicting the lifespan of LED products based on accelerated test data. TM-28 is used in conjunction with LM-84 to calculate the L70 and L50 values for LED luminaires. TM-21 complements LM-80 for predicting the lifespan of single LEDs or modules. These models use statistical methods to analyze the data collected during accelerated testing and extrapolate the long-term performance of LEDs under normal operating conditions.​

3. LISUN LEDLM-84PL Test System: Architecture and Features​

The LISUN LEDLM-84PL is a highly advanced LED Optical Aging Test Instrument specifically designed for lumen maintenance and aging life testing of LED luminaires. Its architecture is composed of several key components that work together to ensure accurate and efficient testing.​

3.1 Temperature Chamber​

The system is equipped with the GDJW Series High and Low Temperature Chamber. This chamber can create a wide range of controlled thermal environments, which is essential for simulating different operating conditions that LED luminaires may encounter in real life. The temperature range and stability of the chamber are carefully calibrated to meet the requirements of various testing standards. For example, it can precisely maintain temperatures required for both normal and accelerated aging tests, ensuring that the LED samples are exposed to consistent and accurate thermal conditions throughout the testing process.​

3.2 Power Supply​

The LSP-1KVARC AC Power Source is another crucial part of the LEDLM-84PL system. It supplies a stable alternating current to the LED luminaires being tested, simulating the actual voltage conditions they will operate under. The power source can be adjusted to match the rated voltage and current of different LED products, ensuring that the testing is carried out under realistic electrical conditions. This helps in obtaining accurate data on how the LED luminaires perform under normal and abnormal power supply scenarios.​

3.3 Integrating Spheres​

The LEDLM-84PL system comes with customized integrating spheres. These spheres are available in different sizes, such as a 0.5m sphere for testing LED bulbs and a 1.2m sphere for LED tubes. Additionally, there are specific terminals designed for testing outdoor luminaires. Integrating spheres play a vital role in accurately measuring the total light output (lumen) of LED products. They collect and uniformly distribute the light emitted by the LEDs, allowing for precise optical measurements to be taken.​

3.4 Data Acquisition and Control Software​

The data acquisition and control software of the LEDLM-84PL system is based on the principles of IES TM-28 and other relevant standards. This software automates the entire testing process, from data recording to curve plotting and lifespan prediction. It continuously monitors and records parameters such as lumen output, colorimetric values, and electrical characteristics of the LED luminaires at predefined intervals. The software then uses advanced algorithms to analyze the collected data, generate detailed reports, and plot graphs showing the degradation trends of the LED products over time.​

4. Detailed Lumen Maintenance Test Procedure with LEDLM-84PL​

4.1 Test Preparation​

Before starting the test, careful preparation is required. First, select the LED luminaires to be tested and ensure they meet the relevant specifications. Then, install the LED luminaires into the GDJW temperature chamber. Up to 8 luminaires can be tested simultaneously in the LEDLM-84PL system. Connect the luminaires to the LSP-1KVARC AC Power Source and the integrating sphere terminals according to the correct wiring diagram.​

Next, calibrate the environmental parameters of the temperature chamber. Set the temperature to the required test conditions, which may include normal operating temperature (e.g., 25°C) and elevated temperatures for accelerated aging tests (e.g., 65°C, 85°C). Also, adjust the power supply to match the rated voltage and current of the LED luminaires.​

4.2 Initial Measurements​

After the setup is complete, perform initial measurements of the LED luminaires. Use the integrating sphere and the data acquisition system to record the initial lumen output, colorimetric parameters (such as CIE x, y values), and electrical characteristics (including voltage, current, and power consumption) of each luminaire. These initial values serve as the baseline for comparison during the subsequent testing process.​

4.3 Testing Process​

4.3.1 Traditional Long-Term Testing​

For the traditional long-term lumen maintenance test, which can last up to 6,000 hours, power on the LED luminaires and maintain the specified temperature conditions in the chamber. Periodically measure the lumen output, color, and electrical parameters of the luminaires at predefined time intervals. For example, in the first 1,000 hours, measurements may be taken every 100 hours, and after that, every 500 hours. The data acquisition and control software will automatically record these measurements and store them for further analysis.​

4.3.2 Accelerated Aging Testing​

Accelerated aging testing is a more efficient way to predict the long-term performance of LED luminaires. In this method, the LED luminaires are subjected to elevated temperatures (such as 85°C or 105°C) to speed up the lumen decay process. Similar to the traditional test, measure the relevant parameters at regular intervals during the accelerated test, but over a shorter total duration (e.g., 1,000 hours).​

4.4 Data Analysis and Lifespan Prediction​

Once the testing is completed, the data acquisition and control software of the LEDLM-84PL system will analyze the collected data. It calculates the lumen maintenance ratio (LMR), which is the ratio of the lumen output at a specific time to the initial lumen output, expressed as a percentage. Based on the LMR values over time, the software can determine key metrics such as L70 and L50.​

Using the principles of IES TM-28, the software also applies statistical methods to predict the lifespan of the LED luminaires. It takes into account factors such as the variability among different samples and provides confidence intervals for the lifespan predictions. The software then generates detailed reports and graphs that clearly show the lumen maintenance performance and predicted lifespan of the LED luminaires, providing valuable insights for manufacturers and researchers.​

5. Practical Applications and Advantages of LEDLM-84PL​

5.1 Practical Applications​

5.1.1 Manufacturer Quality Control​

For LED manufacturers, the LEDLM-84PL system is an indispensable tool for quality control. Before releasing products to the market, manufacturers can use this system to test the lumen maintenance and aging life of their LED luminaires. By ensuring that their products meet the required standards and performance expectations, manufacturers can enhance their brand reputation and customer satisfaction.​

5.1.2 Research and Development​

In the field of LED research and development, the LEDLM-84PL system helps researchers understand the performance degradation mechanisms of LED luminaires under different conditions. It enables them to test new materials, designs, and manufacturing processes, and evaluate their impact on the lumen maintenance and lifespan of LEDs. This information is crucial for developing more efficient and durable LED products.​

5.1.3 Certification Laboratories​

Certification laboratories rely on accurate and reliable testing equipment to assess the compliance of LED products with international standards. The LEDLM-84PL system, with its adherence to IES standards and high testing accuracy, provides a trusted solution for conducting lumen maintenance and aging life tests. It helps laboratories issue valid certifications for LED products, ensuring that consumers can make informed purchasing decisions.​

5.2 Advantages of LEDLM-84PL​

5.2.1 High Efficiency​

The LEDLM-84PL system allows for the simultaneous testing of up to 8 LED luminaires, significantly increasing the testing throughput. Additionally, it can be connected to multiple temperature chambers, enabling parallel testing of different samples or conditions. This high efficiency helps save time and resources, especially for large-scale testing projects.​

5.2.2 Customization​

With its range of customizable integrating spheres and fixtures, the LEDLM-84PL system can accommodate various types of LED luminaires, from small bulbs to large outdoor lighting fixtures. This flexibility makes it suitable for different applications and product designs in the LED lighting industry.​

5.2.3 Automation​

The fully automated nature of the LEDLM-84PL system reduces the potential for human error during the testing process. The data acquisition and control software automatically records and analyzes data, generates reports, and plots graphs. This not only improves the accuracy of the test results but also reduces the labor required for testing, making the overall process more cost-effective.​

5.2.4 Accuracy​

By strictly following international standards and using advanced measurement technologies, the LEDLM-84PL system ensures highly accurate test results. Its ability to precisely control environmental conditions, power supply, and optical measurements, combined with reliable data analysis algorithms, provides manufacturers and researchers with trustworthy information about the lumen maintenance and aging life of LED luminaires.​

6. Conclusion​
The lumen maintenance test method, as implemented by the LISUN LEDLM-84PL LED Optical Aging Test Instrument, is of great significance in the LED lighting industry. It provides a standardized, accurate, and efficient way to evaluate the long-term performance of LED luminaires. By understanding the relevant industry standards, the architecture and features of the LEDLM-84PL system, and the detailed testing procedures, manufacturers, researchers, and quality control personnel can make better use of this technology to improve product quality, drive innovation, and ensure the reliability of LED products in the market.​

As the demand for high-quality LED lighting continues to grow, the importance of accurate lumen maintenance testing will only increase. The LISUN LEDLM-84PL system, with its advanced features and capabilities, is well-positioned to meet these evolving needs and contribute to the further development of the LED lighting industry.​

References​
IES LM-84-14, “Measuring Optical Radiation Maintenance of LED Lamps, Light Engines, and Luminaires,” 2014.​
IES LM-80-2015, “LED Lumen Maintenance and Aging Life Test,” 2015.​
IES TM-28-14, “Projecting Long-Term Lumen Maintenance of LED Luminaires,” 2014.​
IES TM-21-11, “Projecting Long-Term Lumen Maintenance of LED Packages, Arrays, and Modules,” 2011.​
LISUN Group, “LEDLM-84PL LED Lumen Maintenance and Aging Life Test System Technical Manual,” 2025.

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