Test: Evaluation of the service life of LED street lights.

1. Core evaluation method
Light decay index (L70 standard)
The life of LED street lights is usually defined as the time required for the luminous flux to decay to 70% of the initial value (i.e. L70). This index is calculated by fitting the curve of long-term test data (such as more than 6000 hours) and is a generally recognized life judgment standard in the industry.

Electrical parameter monitoring
Regularly detect changes in parameters such as voltage, current, and power factor, and analyze the impact of the stability of the driving power supply on the life. High temperature or current fluctuations will accelerate light decay, and it is necessary to combine constant current power supply design for evaluation.

Thermal management evaluation
Junction temperature is a key factor affecting life. Through heat sink design (such as air cooling/liquid cooling) and temperature sensor monitoring, ensure that the chip temperature is within a safe range (generally not exceeding 85°C)111.

2. Impact of environmental factors
Temperature, humidity and salt spray
High temperature will accelerate material aging, and excessive humidity can easily lead to circuit corrosion. Salt spray testing (such as GB/T 2423.17 standard) is required in coastal areas to verify the protection level (IP65 or above is preferred).

Mechanical stress
Vibration, wind load, etc. may cause the structure to loosen, and vibration resistance tests (such as IEC 60068-2-6 standard) are required to evaluate the mechanical stability of the lamp.

3. Test standards and experiments
Mainstream industry standards

IES LM-80: Used for LED light source luminous flux maintenance rate testing, requiring at least 6000 hours of data.

IESTM-21: A mathematical model for estimating long-term life based on LM-80 data.

GB/T 33720: Chinese national standard, covering indicators such as light decay and color temperature drift.

Accelerated life test
By increasing the current intensity or ambient temperature (such as 85℃ high temperature test), simulating long-term use status and shortening the test cycle, typical experimental designs include:

Constant current accelerated aging test
Temperature cycle shock test7.

4. Factors affecting actual life
Component quality

Light source: Imported chips (such as CREE, Lumileds) have a life of more than 50,000 hours, while inferior lamp beads may have a life of less than 20,000 hours.
Power supply: The service life of a high-quality driving power supply is about 30,000-50,000 hours, and it must have overvoltage/overcurrent protection function.

Maintenance and management
Intelligent control systems (such as remote monitoring and adaptive dimming) can reduce energy consumption by 20%-40%, and extend the actual service life through fault warning.

5. Typical case reference
Municipal road application: LED street lights with IP66 protection + aluminum heat dissipation structure have a measured service life of 8-10 years (about 50,000 hours) in an environment of -30℃~50℃.
Tropical region project: After passing the salt spray test + 2000 hours of accelerated aging experiment, the light decay is controlled within 15%, and the expected service life exceeds 7 years.