A common concern with LED strip lights is whether or not they maintain their brightness or dim over time.  While they can dim over time it is a different process compared to incandescent, halogen or fluorescent lighting and it occurs at a much slower rate than the older types of technology. 

Understanding Lumen Maintenance (L70)

The industry process for measuring the useful life of a LED product is based on something called Lumen Maintenance and making use of the L70 rating.

What is a L70 rating?

L70 is the point in time (measured in hours) when an LED light source has reached 70% of its initial light output (this is measured in lumens).  If the LED strip has a L70 rating of 50,000 hours this means that it will still run at the equivalent of 70% of the brightness it had when it was brand new.  The human eye should not be able to perceive a difference in the amount of brightness in a light until it reaches this 70% threshold.

Why Does LED Strip Dim Over Time?

LEDs can fail due to gradual degradation and this manifests as reduced light output. This can happen for the below reasons:

1. Thermal Degradation

Heat is the most significant factor that can affect the LED lifespan of the strip and its lumen maintenance.  The semiconductor chip inside of a LED generates heat and if this heat is not properly managed an increase of temperature can accelerate the degradation of the chip and the phosphor coating.  It is worth noting that if you have a driver connected to the LED this is also sensitive to heat and if this fails it can also contribute to the LED becoming dim. 

2. Current Density

Operating an LED at higher currents than it has been for to try and achieve a brighter output can generate more heat and accelerate the degradation of your LED strip.  This is why you must use LED drivers and dimmer switches that are designed to operate on the same voltage and current. High-quality LED strips will be designed with optimal heat sinks and current control to handle any fluctuations in current outside of your control.