IACS CO., LIMITED (Yiwu Fuwei e-commerce firm)

The biggest characteristic of LED light source is long life, which can reach 50,000~100000 hours. It is not practical to monitor its light decay condition for a long time. Therefore, this standard will predict the life of LED lighting fixture through an accelerated life test method.

Scope of application

This standard applies to the life test of various types of LED lighting fixtures, and does not include the test of the power supply part of the lamps.

  skills requirement

The light output of the LED luminaire is 70% of the initial light output as an indicator of the life judgment failure.

Test method one

Junction temperature is an important cause of LED light attenuation. An increase in junction temperature can cause LED light to decay quickly. LEDs operating at high currents generate more heat and accelerate aging.

This test method uses different driving currents, selects 5 LED lamps, and accelerates life test with different currents at 25 °C ambient temperature to obtain a mathematical model of light output attenuation.

  mathematical model

y=exp(-αt)

α=m×exp(nI)

Where y is the relative light output, α is the decay constant, t is the lighting time, m and n are constants, and I is the test current.

According to the test data about y and t obtained under different currents, the attenuation coefficient α about different lamps is finally obtained, and the lifetime value of the luminous flux maintenance rate at 70% is obtained.

Test method two

Using temperature as a constant acceleration stress, the life expectancy at 70% of the LED lamp failure criterion at 25 ° C is derived.

Five LED lamps of the same specification were selected to adjust the temperature of the oven at 50 °C, 80 °C, 100 °C, 120 °C, and 150 °C, respectively, under the conditions of constant current and constant current conditions as constant acceleration.

Record all parameters of the five sets of LED reliability test procedures: light output (illuminance or light intensity or luminous flux), test time, current, power, junction temperature, etc.

Using the Arrhenius mathematical model

P=P0exp(-βt)

β=β0IFexp(-Ea/kTj)

P0 is the initial light output, P is the light output after heating and heating t time, β is the attenuation coefficient at a certain temperature, t is the power-on working time at a certain temperature, β0 is a constant, and Ea is the activation energy. , k is the Boltzmann constant, IF is the operating current, and Tj is the junction temperature.

Through formula transformation and experimental data

Ea=[K×In(t2/t1)]/(1/Tj2-1/Tj1)

T2=t1×exp[Ea/K(1/Tj2-1/Tj1)

Thus, it is judged that the failure at 25 ° C is judged to be 70% of the life expectancy.

Yiwu Fuwei e-commerce firm (IACS Co., Limited) is a very professional Led manufacturer who produces high quality outdoor led light. Our popular products are solar led lights, UFO lights, underwater lights and so on. If you have any question about the led product, please feel free to contact us.