Ways to extend lifespan of outdoor LED bulbs controlled by motion sensor

At home we have 2 outdoor motion sensors that drive the outdoor pathway lights. However, the lights are non-dimmable 6W LED GX53 bulbs, and half of them died within 2 years of use. I suppose because of frequent on/off cycles.

I am now wondering how I could smarten the outdoor pathway lights and at the same time lengthen their lifespan. Would it make sense to use dimmable lights and finding a way to smoothly power on the lights (even at low dim level) to this end?

LEDs should not suffer fron on-off any more than any other electronics; they are electronic too. Likely you just had poor quality bulbs, this happens sometimes. More specifically, LEDs themselves are perfectly fine but their power supply died.
Try buying a different brand from different vendor.

I also believe the power electronics died prematurely.

The main problem is that these lights are mounted on the façade and are exposed to weather. So I guess humidity and low temperature may have killed the lights.

I may have to replace the current lights with weather proofed light appliances.

I’ve found LED lights very variable in reliability, with worst culprits being cheap Chinese made “replacement for bulb” style.

Indirectly - I would guess more about thermal shock, getting hot internally rapidly from very cold. You should use proper exterior fittings really.

The LED lights have a GX53 fitting and are mounted in an outdoor proof fixture mounted on the façade. In replacing the defective lamps, I noticed no humidity at all in any of the fixtures.

My reasoning was that, if I could run the lights at lowest power when it’s cold, then I could avoid thermal shock in the fragile power circuit (which basically converts 230VAC to 5VDC).

I could then write a rule that would manage light intensity (dimmer) depending on how “cold” the lights are. I could factor in outdoor temperature with the last time the lights were switched on, for instance, in an OH rule.

I don’t believe a dimmer would be able to solve the problem. LEDs are not incandescent, traditional dimmers for them are just a legacy thing, and dimmable LEDs have hard times pretending to be incandescent. That’s why they don’t dim so well; dim only halfway down, then start to visibly blink, then completely shut off.
If you imagine a typical AC sine wave, the dimner works by interrupting the power faster than a half period completes. As a result, sine wave turns into somewhat triangular “spikes”. But electronics really doesn’t want that,it wants a nice constant power supply. Yes, the bulb has a rectifier and a big capacitor to keep up with that. And shorter power bursts mean it actually has to draw more current to keep the cap charged. Increased consumption also causes a buzzing sound in the dimmer on low settings.
So, legacy AC dimmer is not a solution.

1 Like

I agree that a simple legacy AC dimmer won’t work. I’m more looking into electronic dimmers that will cut the phase, either in the up or down slope.

No, a dimmer is not working. The LED runs on about 2 - 2.5 VDC (depends on the actual material compination used and very much on temperature). Your mains AC is transformed and rectified to obtain a DC supply voltage.
The cheap way is to use a resistor to reduce the voltage to the required drop at the LED. The expensive way is to use a constant current source or sink to supply.
To “dimm” the LED, you use PWM (pulse width modulation), that is a very fast switch on/off of the LED which you can’t see with your eyes.

LEDs get destroyed from local overheat and a “thermal runnaway”. The thermal connection of the semiconductur die to the heat spread is the key for lifetime. Design and process quality have a huge impact on this. Thermal cycling + humidity and frost may have a damaging effect on the thermal connection.

Well, it’s impossible to qualify such a product as a consumer. So you need to put your trust on brands.

1 Like