LED home lighting; not quite ready or ready for prime-time?

[Music Lover]

Quote:

Originally Posted by UpAnchor Al, do you have any of those floods on a dimmer? I'd like to do likewise at some point with my recessed cans but they're all on dimmers and I've found that some "dimmable" LEDs can be rather erratic.

They do make LED rated dimmers which are supposed to solve that problem.

[ERD50]

A little background on dimmer issues:

All modern dimmers "chop" the waveform - they act like a fast, synchronized (120 times per second) on/off switch. This technique lowers the average voltage. I think some LED/CFL dimmers might "chop" at an even higher rate than just the line cycles, but this works fine for filament bulbs as well.

The ones rated for LED/CFL are capable of handling a reactive load (capacitive, inductive, power factor< 1), while the older, non-LED/CFL rated dimmers are only rated for a resistive load (traditional filament bulb, resistive, power factor near 1). And if they are rated for LED/CFL, they will work fine for filament bulbs as well.

However, in my experience, and that of others (read the reviews), the LED/CFL dimmers do not always work so well with all dimmable LEDs.

-ERD50 (retired Electrical Engineer)

[FIREmenow]

Quote:

Originally Posted by ERD50 I'm sorry, but this information is not true. You might consider deleting your post to avoid confusing others (then I will do the same). [snip] However, in my experience, and that of others (read the reviews), the LED/CFL dimmers do not always work so well with all dimmable LEDs. -ERD50 (retired Electrical Engineer)

Thanks for the clarification. So deleted.

[ERD50]

Quote:

Originally Posted by FIREmenow Thanks for the clarification. So deleted.

Thanks - I edited my post to just make it generic info for those interested.

-ERD50

[Sunset]

Quote:

Originally Posted by ERD50 Thanks - I edited my post to just make it generic info for those interested. -ERD50

Since you are so knowledgeable about dimmers. I've avoided them as I thought they waste a lot of electricity. Do they ?

[Just_Steve]

I have dimmers on all of the recessed led I put in and have no issues, and my dimmer switches are old.

[NW-Bound]

Just had the 1st LED bulb failure. It is also the 1st LED I bought, perhaps 2 years ago, and is a brand-name bulb too. It's a Cree, and Cree makes the diodes that other manufacturers buy to put into bulbs. Paid around $10 for it back then.

When I tried to remove it from the socket, it turned on again. Then, it quit a few days later. Apparently, a bad connection inside the bulb electronics.

The LEDs themselves may last a long time, but other electronic components including soldered connections can still fail.

[NW-Bound]

Quote:

Originally Posted by Sunset Since you are so knowledgeable about dimmers. I've avoided them as I thought they waste a lot of electricity. Do they ?

Electronic dimmers are not like resistive rheostats, hence do not waste power the same way.

Electronic dimmers work by controlling what percentage of the 60-Hz AC cycle they conduct. It's like your air conditioning thermostat turning the compressor on/off as needed to regulate temperature, although the dimmers work at the 120-Hz rate (every half-cycle or 2x the 60 Hz frequency).

On the other hand, resistive rheostats work by blocking the current with a variable resistance. This extra resistance heats up, and wastes power.

Another important point to note about electronic dimmers when used on incandescent lamps. This causes a lot of waste, but it's because of the incandescent filament characteristics. A 100-W bulb when dimmed to 60 W does not put out the same light intensity as a 60W bulb. When the filament does not get sufficiently hot to emit light, it's just heat that they produce. And when dimmed to 25W, a 100W bulb barely glows red compared to a real 25W bulb.

So, dim away your LEDs. It's good for you.

PS. Just saw what ERD50 posted. True, the electronics in the dimmer may not be compatible with the electronics inside the LEDs. It's more complicated than dimming an incandescent filament, which is just a resistive element.

[ERD50]

Quote:

Originally Posted by Sunset Since you are so knowledgeable about dimmers. I've avoided them as I thought they waste a lot of electricity. Do they ?

No, dimmers will generally save energy. As I mentioned, they are fast "on/off" switches. If you think of it in slooooooowwwwww mooooootioooon, a dimmer that is set at 50%, it would be like comparing a light that is on 24 hours a day, versus one that is turned off each alternate hour and then on again, so on just 12 hours a day. It will use ~ half the power. But they switch 120 times per second, some designs switch even faster, chopping each cycle several times.

The dimmer itself uses/wastes almost no electricity. When it is switched OFF, there may be a tiny leakage current. When it is ON, there will be a small voltage drop. And a very small amount wasted as it switches. But these are small. If they were not, you could not have a 600W rated dimmer in a switch housing - it would get very hot if it were wasting much power. Most dimmers run barely warm.

One (probably minor) caveat. A 100W filament bulb dimmed down to consume 60 watts, will put out less light than a 60 W bulb. It just isn't at its most efficient part of the curve. But this is generally offset by the actual savings if you do need the full brightness sometimes, and run it dimmed at other times.

The take-away there is, don't put a bigger bulb in there than you actually need. If you are always dimming it, use a smaller bulb, and run it at a higher setting. But these aren't really large effects - but I'd pay attention if it was a light that was on many hours on average.

I'm not sure about those same effects in dimmable LED/CFLs. I'd assume some similar effect, but they already are using less power, so the absolute differences will be smaller anyhow. I wouldn't worry about it unless it was an extreme mismatch - and if extreme, the control would be 'touchy' if you were using just 10% of the range of the dimmer. A better match would be better all around.

edit: ooops! cross posted much of what NW-Bound pointed out. That's the nice thing about facts over opinion - facts are the same everywhere, no matter the source!

-ERD50

[ERD50]

Quote:

Originally Posted by NW-Bound ... A 100-W bulb when dimmed to 60 W does not put out the same light intensity as a 60W bulb. When the filament does not get sufficiently hot to emit light, it's just heat that they produce. And when dimmed to 25W, they barely glow red compared to a real 25W bulb. So, dim away your LEDs. It's good for you.

Maybe after lunch, I'll get my Kill-a-watt meter out and actually try this out, to see just how big the effect is. Hmmm, I could try an LED as well. I suspect the driver in the LED will have a 'sweet spot' as well, but probably a small effect?

Although, I generally like the 'warm' red-shift of a dimmed filament bulb. It actually seems odd to dim an LED, and still have the same white light. It is very obvious (if you look at the bulbs) in my fixtures with a mix of filament and LED (to damp out the reactance that causes problems in my dimmers). Though with the fancy LED 'bulbs' with separate programmable R-G-B LEDS, this effect could be programmed in.

-ERD50

[ERD50]

Quote:

Originally Posted by Just_Steve I have dimmers on all of the recessed led I put in and have no issues, and my dimmer switches are old.

Some dimmers seem to work well with some LEDs. I'm glad yours work for you, can you post the model #'s of each?

From my experience, and many reviews, it really seems to be hit-miss to get a combo that works well throughout the dimming range, and manufacturers may make changes at any time. Like I said, I think the industry needs a better certification test, it isn't as plug-and-play as it should be. Any LED/CFL dimmable labeled component ought to work with any other such labelled component.

-ERD50

[ERD50]

Quote:

Originally Posted by NW-Bound Just had the 1st LED bulb failure. It is also the 1st LED I bought, perhaps 2 years ago, and is a brand-name bulb too. It's a Cree, and Cree makes the diodes that other manufacturers buy to put into bulbs. Paid around $10 for it back then. When I tried to remove it from the socket, it turned on again. Then, it quit a few days later. Apparently, a bad connection inside the bulb electronics. The LEDs themselves may last a long time, but other electronic components including soldered connections can still fail.

I am looking forward to a full tear down, analysis, and maybe even a fix!

-ERD50

[jazz4cash]

My LED issue is compatibility with a remote motion detector that signals an electronic wall switch. System is made by Lutron and the lights are in the driveway. The bulbs never turn completely off. I tried adding a nightlight (4W) to the circuit which helped but only a bit. I figured I needed a bigger resistor on there but decided to go with halogen energy saver($$) bulbs instead. They burned out quickly so I switched back to std bulbs. I'll need to find some other fixture to provide a driveway light.


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[ERD50]

Quote:

Originally Posted by jazz4cash My LED issue is compatibility with a remote motion detector that signals an electronic wall switch. System is made by Lutron and the lights are in the driveway. The bulbs never turn completely off. I tried adding a nightlight (4W) to the circuit which helped but only a bit. I figured I needed a bigger resistor on there but decided to go with halogen energy saver($$) bulbs instead. They burned out quickly so I switched back to std bulbs. I'll need to find some other fixture to provide a driveway light. Sent from my iPhone using Early Retirement Forum

The older night lights are 7 watts (or maybe a C-7 Christmas bulb?) - that might be enough of a resistive load to let it turn off properly if 4 W got close.

But by the time you go to a 25 watt bulb, there might not be any savings over just leaving an LED on 24/7!

I had to do that with the old timer I had connected to our porch/garage lanterns (6 in total). A few years ago, I had to replace that timer, and the new one has actual relays in it, so no problems now. And the astronomical calendar in it means I never need to fiddle with the on times as the seasons change - it's always on at dusk (reliably, not dependence on light levels and it is inside the garage anyhow).

-ERD50

[NW-Bound]

Quote:

Originally Posted by ERD50 I am looking forward to a full tear down, analysis, and maybe even a fix! -ERD50

I did save the bulb to look at later, on a rainy winter day. Heh heh heh...

But a cold rainy day in the southwest happens once every 5 years. I will try to remember the bulb when the occasion arises.

About dimming LEDs, I converted the lights inside my motorhome to LED and posted about it a while back. Bought the 10W LED capsules off eBay from China ($6 each back 5 years ago), and built a current regulator for each lamp. Current regulators are needed because the 12V off the battery is actually higher than 14V when the battery is being charged. The LED capsule current draw reaches the rated 1A when the applied voltage is barely above 9V, and 12V is already enough to burn it out.

Instead of having the regulated current preset at a fixed level, I put in control in each circuit to vary the current for dimming. Works great.

Oh, here are the photos posted back then. The whole thing is hidden inside the existing fixtures. Note the copper strap used as a heat spreader, and the aluminum finned heatsink on the switching regulator IC. Each LED capsule puts out 600 lumens max, and I had 10 fixtures converted (a couple of fixtures are dual bulb). With all of them turned on, they draw less than 10A total and make the interior so bright my wife has to wear shades. Heh heh heh...

[Al in Ohio]

Quote:

Originally Posted by UpAnchor Al, do you have any of those floods on a dimmer? I'd like to do likewise at some point with my recessed cans but they're all on dimmers and I've found that some "dimmable" LEDs can be rather erratic.

Mine are not on a dimmer so I can't say.


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[RockyMtn]

We went totally led inside and outside on our recent major remodel. All of the interior recessed led's are on dimmers designed for led's so they work fine. I do wish they would dim a bit more but we just turn on fewer of them.

After a month or two we did change out the recessed led cans over one of the kitchen islands for some led pendant lights. The recessed were just too bright even when turned down low. My DW wanted some 50 year old friendly light for our nightly happy hour! The pendants hummed when we turned the dimmer down with 50w equivalent bulbs so switched to a 25w equivalent and the hum went away and they dim enough to keep her happy.

On the outside we used low voltage led's in the garden. In the sconce lights around the outside of the house/front porch and over garage door we used LED bulbs from Costco. They are on dimmers as well. We also have a couple that have photocell adapters so that they come on automatically each night.

We still like incandescent for some table lamps and the dining room chandelier.

Given all of the leftover cfl's and incandescent bulbs and the switch to led I can't imagine I'm going to be buying a whole lot more light bulbs in my life!

[ERD50]

Quote:

Originally Posted by RockyMtn We went totally led inside and outside on our recent major remodel. All of the interior recessed led's are on dimmers designed for led's so they work fine. I do wish they would dim a bit more but we just turn on fewer of them. ....

On the LED compatible dimmers I have, there is an adjustment underneath the switch plate that sets how low they go. The instructions say to set this lower and lower while turning the light on and off. Then raise it a bit from the point where they don't reliably turn back on.

If it is set too low, the lamps may not turn on when just flicking the switch, if the dimmer was already all the way low. Due to normal line voltage variations, you want to give it a little margin.

But if it is just mood lighting, I guess you could turn it down - you would know to turn it up a little if they didn't come on with the switch flip.

-ERD50

[RockyMtn]

Quote:

Originally Posted by ERD50 On the LED compatible dimmers I have, there is an adjustment underneath the switch plate that sets how low they go. The instructions say to set this lower and lower while turning the light on and off. Then raise it a bit from the point where they don't reliably turn back on. If it is set too low, the lamps may not turn on when just flicking the switch, if the dimmer was already all the way low. Due to normal line voltage variations, you want to give it a little margin. But if it is just mood lighting, I guess you could turn it down - you would know to turn it up a little if they didn't come on with the switch flip. -ERD50

If I set it them any lower they flicker. Don't want a lower wattage as we do need them on full at times.

[JoeWras]

I find the quality of the LED bulb/unit affects the quality if dimming, even with a high quality LED compatible dimmer.

For instance, I have some recessed lighting replacements. One is 3x more expensive than the other. The more expensive one dims more reliably. I find that the real cheap ones sometimes "flash" unexpectedly while dimmed.