The hidden, extremely costly LED lighting maintenance

[Electric-Light]

I am not sure how they did away with the electronics, but it works great. I having some ceiling lights with mixed incandescent and LED bulbs. You can not tell the difference between the old and the new when it on or off.

View attachment 18079

Here a link to them at HD:
http://www.homedepot.com/p/EcoSmart-60W-Equivalent-Soft-White-B11-Filament-E12-Energy-Star-and-Dimmable-LED-Light-Bulb-3-Pack-B1160WFILE123P/300657417

LEDs require a ballast. A keychain light that direct drives a single element emitter from two 3v coin cells in series is ballasted by the high internal resistance of the coin cells. The LED element will fry quickly if it was connected to a low impedance source like a 6v NiCd pack.

When you wave your hand in front of it or flip through book pages, do you see this effect?

Every AC utility driven LED products without an electrolytic (or expensive tantalum or absurd quantity of ceramic caps) caps suffer from this due to the lack of glow persistence of the phosphor blend used in blue LED excitable fluorescent material. The after glow that lasts for several seconds on some LED bulbs is not because of phosphors, but the LEDs being kept up by how and amount of capacitor in the ballast.

Each LED filament is a stack of LED elements wrapped in a phosphor impregnated sleeve. The capacity of stand still air is limited. They are gas cooled to allow increased power input. The filaments are put in a glass bulb like a normal light bulb but filled with helium which has about 6x the thermal conductivity of air.

LEDs must be ballasted but does not have to be a transistorized electronic ballast. it can be just a series resistor or a capacitor on its own or with a bridge rectifier. If it's just a resistor, the filaments are wired back to back internally or externally and they alternate between two sets each half cycle and pass on the extreme flicker. If there is minimal flicker, there is a capacitor inside the base. The resistor could also be hidden somewhere within the gas cooled bulb.

You WILL find the ballast if you rip the base off and carefully trace all path leading to the LED filaments. Usually, those that use full size (medium base) sockets have a capacitor to flywheel the LED current to prevent inferior light quality caused by flickering.

A passively ballasted LED lighting without a switch mode transistorized LED ballast is not expected to spaz blink when it fails, but it will produce light that is inferior to incandescent, fluorescent or HID in some way, because the light will have a percent flicker of 100% and a flicker index of about 0.5 (out of 0 to 1.0).

 

[big john]

...

 

[Besoeker]

The last two LED bulbs we bought were £1.00 each. Less than a buck and a half. So, not really extremely expensive.

 

[Electric-Light]

The last two LED bulbs we bought were £1.00 each. Less than a buck and a half. So, not really extremely expensive.

Not the cost of it, it's the cost of emergency replacement when it spaz blink fails in a difficult location.

 

[Besoeker]

Not the cost of it, it's the cost of emergency replacement when it spaz blink fails in a difficult location.

At the risk of being repetitive, I have not had a single one fail nor a single report of of any of the thousands we fitted to industrial panels.
No failures = no cost.

 

[zbang]

Not the cost of it, it's the cost of emergency replacement when it spaz blink fails in a difficult location.

How often does this actually happen? How often are "emergency replacements" needed for any other kind of lamp? I really doubt that anyone is getting called out at 3am to fix a single flickering fixture (unless it's an airport or similar). Next day replacement isn't "emergency" in my book, it's simply a service call.

And how is an LED different from an HID when it starts acting up? Most people ignore those for days (weeks?).

 

[Fulthrotl]

And how is an LED different from an HID when it starts acting up?
Most people ignore those for days (weeks?).

the flashing rate is once ever seven minutes or so?
slower flash rate, slower response time?

 

[Besoeker]

How often does this actually happen? How often are "emergency replacements" needed for any other kind of lamp? I really doubt that anyone is getting called out at 3am to fix a single flickering fixture (unless it's an airport or similar). Next day replacement isn't "emergency" in my book, it's simply a service call.

And how is an LED different from an HID when it starts acting up? Most people ignore those for days (weeks?).

Nail on head if I may say so.

 

[Electric-Light]

How often does this actually happen?

I'd say less often now than before, because it has become more common for LED fixture builders to use thermal folding ballasts. The ballast uses its internal dimming circuits or a sensor on the LED board to trigger the dimming capability to override the output in order to limit temperature to prevent abnormal aging or failure. This only delays the failure and makes it difficult to perform accelerated failure testing. It doesn't mean it features a spaz blink proof ballast circuit design.

Onto another matter but we should encourage requirements that call for an indicator lamp to show thermal throttling activation along with calling for spaz blink proof ballast design. Thermal folding introduces the problem of creating more opening for undetected chronic specification failure since routine activation of safe-mode can go undetected. It's ok for a truck to lose output because a big trash bag got sucked into the grill and went unnoticed but you expect an indicator to light up in the dash when this happens. A pattern of going into safe-mode every time it is towing within capacity in the summer due to inadequate cooling system is a design flaw and this is not ok. "thermal management" that is gaining traction masks spec failures caused by design faults and this is something to keep in mind as many retrofit kit and LED fixtures are owned and operated by marketing people who just cram off the shelf LED engines into a box. Many premature LED degradation and ballast failures are already attributed to fixture design failures. If specs call for 12,000 delivered, it's a failure if it regularly trips on thermal throttling and folds back to 9,000 lumens on a regular basis even if it is not noticed. If 9,000 was acceptable, specifying 9,000 or 10,000 instead of 12,000 could have gotten better prices. Since LEDs don't become more efficient by getting hotter, appreciable loss of wattage going to a large group of LED installation from power-up to an hour later on a warm day is a good clue that thermal fold back could be happening.

Laying out a ban on spaz blink fallible fixtures and setting requirements on how spaz blinks must be dealt with, as well as performance spec non compliance from chronic thermal folding can affect bid pricing compared to remaining silent and carries the potential of making LED look more affordable to own and operate than really are.

Chance of fixture brand going belly up should also be considered when qualifying.
http://luxreview.com/article/2016/1...he-manufacturer-will-fail-than-the-led-driver

How often are "emergency replacements" needed for any other kind of lamp? I really doubt that anyone is getting called out at 3am to fix a single flickering fixture (unless it's an airport or similar). Next day replacement isn't "emergency" in my book, it's simply a service call.

And how is an LED different from an HID when it starts acting up? Most people ignore those for days (weeks?).

Generally, only electronic LED ballasts can suffer spaz blink failure which can cause the LED to blink at a disco strobe or a fire truck pace. Just disallow it and set how it should be dealt with in the specs reqs and ths ensures the LED dealer is put on the hook to source fixtures using non spaz blink fallible ballasts and they're going to be eating the cost to address spaz blinks as well as replacing or repairing fixtures discovered to be spaz blink fallible.

HPS or common pulse start igniter don't have high enough igniter voltage and it takes many minutes per cycle. Repeatedly firing into a non-starting lamp can not produce a flash anything even close to full output. A failure within the transistorized electronic LED ballast can cause the LED to flash rapidly between zero to beyond full brightness, but what happens when it fails is design dependent.

A worn HPS can drop out when shaken, but restrike does not occur until the lamp fully cools down and the cycle rate is just a bit annoying. Not extremely bothersome like spaz blinking LED.

 

[Besoeker]

I'd say less often now than before, because it has become more common for LED fixture builders to use thermal folding ballasts.

OK. How often compared to say, HID, low pressure, or high pressure sodium?

 

[petersonra]

supposedly the latest problem with LED lamps is that they flash at a high rate that most people cannot actually perceive but some do and it causes them head aches.

 

[gadfly56]

supposedly the latest problem with LED lamps is that they flash at a high rate that most people cannot actually perceive but some do and it causes them head aches.

They have always done that. I loaned my LED Mini MagLite to our IT guy at my last employer so he could check the guts of a desktop he was looking at. He uttered an expletive when he saw the cooling fan wasn't turning. It so happens the MagLite's flash rate was the same as the fan's RPM and it "froze" the fan.

 

[Jraef]

supposedly the latest problem with LED lamps is that they flash at a high rate that most people cannot actually perceive but some do and it causes them head aches.

For a long time, I thought my eyes were going bad because I can perceive that, but only when my sight moves across an LED light source. Since I don't tend to stare at light bulbs, the place I see it most is when looking at tail lights on cars or the new traffic lights now. Staring right at them they appear steady, but when my sight moves, I perceive the flashing as a kind of "stutter". It wasn't until my eye doctor explained it to me that I relaxed about it. I never get headaches from them though. My wife got terrible eyestrain from older mag-ballast fluorescent lighting because it too has a 120Hz strobing effect. Supposedly new electronic ballasts strobe at kHz ranges so it has eliminated that for most people, but we switched to LEDs a couple of years ago anyway and she is fine with them. The thing is, cheaper LEDs use cheaper drivers that don't bother with flicker filtering or PFC control, so they are worse than the better drivers that do, meaning they will have a 120Hz flicker, which might affect the same people that were affected by mag-ballast fluorescent. So for cars, traffic lights and decorations, the cheapest drivers are used because they are not supposed to be light sources for activities like reading. That cheap driver issue might also be true of the "Dollar Store" LED lamps as well. As per usual, you get what you pay for.

 

[wwhitney]

tail lights on cars

Car tail lights are powered by the 12V DC system. So why would there be any AC flicker on car tail lights?

Cheers, Wayne

 

[gadfly56]

Car tail lights are powered by the 12V DC system. So why would there be any AC flicker on car tail lights?

Cheers, Wayne

Why is there flicker on my LED flashlight?

 

[wwhitney]

Why is there flicker on my LED flashlight?

Yeah, I wondered that too, I'm stumped.

Cheers, Wayne

 

[Jraef]

There's still a DC-DC power supply that's using PWM to change the voltage from 12VDC nominal to 5VDC, or on a flashlight, a DC boost converter to step it up, again using PWM.

 

[gadfly56]

There's still a DC-DC power supply that's using PWM to change the voltage from 12VDC nominal to 5VDC, or on a flashlight, a DC boost converter to step it up, again using PWM.

I knew that, I was just trying to be gentle with wwhitney.

 

[GoldDigger]

I knew that, I was just trying to be gentle with wwhitney.

You can also look at it as a way to control current for different light levels. The change in voltage is minimal.
I have one LED flashlight that will work at the lowest output until the battery is dead and will simply fail to switch to the higher output settings.
And another that has "full" and "low" at a fixed ratio to one another and both dim proportionally as the battery voltage drops.
The latter has such a low switching frequency that on low it will not turn off my solar powered garden lights.

Sent from my XT1585 using Tapatalk

 

[wwhitney]

There's still a DC-DC power supply that's using PWM to change the voltage from 12VDC nominal to 5VDC, or on a flashlight, a DC boost converter to step it up, again using PWM.

OK, good to know. So in the DC-DC case, are the manufacturers just being lazy by using a PWM rate that is low enough to be visible to some?

Cheers, Wane