Replacing 50W Halogen GU 5.3 / MR16 with LEDs... unanticipated problem

Forums › Home Workshop DIY › Replacing 50W Halogen GU 5.3 / MR16 with LEDs... unanticipated problem

aros71

122 posts

Master Geek

#168503 16-Mar-2015 15:09

So I moved to a new house in Jan and instead of the usual screw-in downlights, each room is full of incredibly power-hungry 50W halogens. In some cases, eight in one room!

This offends my inner greeny, and my wallet when it comes time to pay the power bills. This is the 2010s... no electrical device has any business getting that hot unless it's a heater!

So I decided to replace them with LEDs; I bought an experimental pack of four and ran them in the kitchen. The LEDs I bought are 5.5w and to my delight the light they gave was just as strong as the halogens they replaced, and a pleasing colour.

Encouraged, I bought a bunch more (not cheaply either!) and set about replacing them.

Then I hit a problem. The 12v transformers need a suitable load to switch on properly, meaning that some of them work well, while some of them flicker intermittently as the switch mode power supply - which is expecting to power 50w - gets asked to power 5w.

For this I have a simple but effective solution - I plan to let one transformer power 4 or 5 lights, connected in parallel. This should work, I hope, but I am wondering if anyone else has done this and can report success or otherwise?

Also - the other slightly annoying phenomenon - when the power company sends the "ripple" signal down the mains to turn on and off the controlled loads (hot water etc) - this causes the LEDS to flicker like crazy. I know it's the ripple because it happens at the same time every night (23:00) and all the LEDs do it simultaneously.

I am guessing this is because the transformers have no regulation, expecting to power a halogen which has slow enough reaction times that some modulation wouldn't make any difference.

I understand you can also get transformers specifically for LEDs - so after all that boring context (thanks for staying with me!), this is my actual question:

Do dedicated LED downlight power supplies contain sufficient filtering/capacitors to prevent the flicker caused by modulation to the power?

If anyone has any experience, please let me know...Right now the Spousal Acceptance Factor for the LEDs is low because of the flickering, but I am not ready to admit defeat and put all the halogens back

[Edited for typos - AR]

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8956 posts

Uber Geek

#1260323 16-Mar-2015 15:13

Can't answer your specific question, but as a side issue, be careful that you don't add too many LEDs per transformer, as you need to account for someone else coming along and replacing the LEDs with the original halogens, and then overloading...

timmmay

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#1260325 16-Mar-2015 15:15

Can you link to what you purchased? The LED downlights I purchased all connect directly to the mains, with their own little black box which I presume is some kind of transformer/driver.

Hopefully your LEDs are rated for insulating over, as 8 downlights in a room lets a massive amount of heat out if you can't insulate over them.

aros71

122 posts

Master Geek

#1260326 16-Mar-2015 15:15

Already thought of that - would leave the original transformers in place, put a wraparound sticker on the power lead saying "Halogen" and run another cable from the other transformer with a wraparound sticker saying "LED only"...

that was my first consideration for this plan... but the other thing I was thinking of was adding a diode and electrolytic on the 12V side to absorb the ripple... or else just getting transformers that will accept it and not pass it on to the lights!

aros71

122 posts

Master Geek

#1260331 16-Mar-2015 15:20

timmmay: Can you link to what you purchased? The LED downlights I purchased all connect directly to the mains, with their own little black box which I presume is some kind of transformer/driver.

Hopefully your LEDs are rated for insulating over, as 8 downlights in a room lets a massive amount of heat out if you can't insulate over them.

Ah you would have got the GU10s, which run on 230v - I'd thought of getting those, but I got the GU5.3 12V ones as I figured they'd be drop-in replacements for the halogens.

In other words, the Mindless Optimism card :D

I got 4 Philips ones, Then 16 of the cheaper (but just as good) house brand ones from Bunnings, then a box of 30 Chinese 12V ones off AliBaba, which come with their own capacitor and diode built in, but are too low power 4.5W) for the transformers to properly start up.

timmmay

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#1260333 16-Mar-2015 15:21

Are you doing this yourself? Do you understand the rules around what home owners can and can't do? I have no idea what they are, though I suspect having someone check and sign off your work would be a good idea.

aros71

122 posts

Master Geek

#1260335 16-Mar-2015 15:23

RunningMan: Can't answer your specific question, but as a side issue, be careful that you don't add too many LEDs per transformer, as you need to account for someone else coming along and replacing the LEDs with the original halogens, and then overloading...

Also I'd put a 5A fuse in the 12V line upstream of the distribution to stop total draw > 60W off the transformer. Trouble is, I've several rooms to do this in, so I want to work out the best plan to avoid expensive trials and errors.

aros71

122 posts

Master Geek

#1260340 16-Mar-2015 15:25

timmmay: Are you doing this yourself? Do you understand the rules around what home owners can and can't do? I have no idea what they are, though I suspect having someone check and sign off your work would be a good idea.

I'f I'm doing anything with Mains - I'd need a ticketed sparky to sign it off. Else if I start a fire and investigation finds it was because of dodgy electrics, the insurance would not pay. However, all the mods I'm planning are on the 12V side, this is precisely the reason I want to utilise the existing transformers if at all possible.

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aros71

122 posts

Master Geek

#1260344 16-Mar-2015 15:26

In an ideal world I'd like to chuck a couple of 120W solar panels up on the roof and some deep-cycle batteries in the garage and run all the lights off that, but I'm not at the stage where I want to rip walls apart yet!!

richms

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#1260351 16-Mar-2015 15:36

Actually not as simple as anything to do with the mains, building regs cover downlights as well, and they have to be approved to the type of insulation cover etc.

If you are modifying the fittings you can come unstuck.

I would just go get some of the combined GU10 LED and downlight kits from bunnings and swap the transformer and fitting out, which you are legally allowed to do in an owner occupied detached house. That way you get a new hopefully better sealed, CA or ICF rated downlight that will cause no doubt about suitability for insulation placement. Old uncovered halogens had to have a massive gap around them and the heat can ones still couldnt be touching so replacing with something hopefully ICF rated and then fixing the insulation holed will give you the best bet.

MR16 lamps tend to be spots, so in downlight use are pretty hopeless at room lighting. Whereas the LED downlights usually have a better spread so make the room seem less dark and closed in like spots that leave the walls dark will do. The only reason there would have been halogens put in is because that was the trend, and when you have a low ceiling like most NZ houses you cant really put nice lights in without causing people to smack their heads on them.

edit:

Also, I was told that putting floating GU10 holders onto an existing fitting that is made to take a floating bipin 12v lamp is also considered a "modification" so would fall foul of any regulations. Any ICF LED with a GU10 lamp in it will have the terminal block on a fixed arm and several other things that seem pointless but are required to get that classification.

Richard rich.ms

Aredwood

3885 posts

Uber Geek

#1260699 17-Mar-2015 00:51

Your halogen transformers output high frequency ac at approx 100khz. and are also designed to pass any mains variations to the output so you can dim them. That high frequency is difficult to rectify and filter. Do you have dimmers? As this changes what the best thing to do to fix your LED issues.

hangon

397 posts

Ultimate Geek

#1261001 17-Mar-2015 13:01

I replaced some 50w halogen bulbs with philips mr16 bulbs (4 pack) from bunnings, was running 35w halogen before. the LED gives out more light and color is pleasing. no flickering. they do have small vents so may not be suitable depending on your requirement.

the bulbs from bunnings are more efficient than some other philips packages I saw in either warehouse or countdown (can't recall).

bunnings also have some hpm led downlight of similar size, only slightly more expensive ($19.95, not showing on their website) than the bulbs. they have integrated driver and no vent. they are ca135 rated so again may not be suitable depending on your requirement.

n4

959 posts

Ultimate Geek

#1261060 17-Mar-2015 13:57

I had the same issue and replaced the transformers which fixed the problem. I used two different types, both costing $10 per unit. The ones I used were the cheapest option from Bunnings, and also these ones. No issue if someone replaces the LEDs with halogens in the future. Its a simple two wire replacement which I class the same as changing a fitting.

Interestingly I didn't see the problem when using the more expensive Phillips bulbs, in bathrooms. Other bulbs, or even Phillips in other locations, I did. Maybe the bathrooms had a better class of transformer to begin with.

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Amosnz

567 posts

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#1261075 17-Mar-2015 14:05

n4: I had the same issue and replaced the transformers which fixed the problem. I used two different types, both costing $10 per unit. The ones I used were the cheapest option from Bunnings, and also these ones. No issue if someone replaces the LEDs with halogens in the future. Its a simple two wire replacement which I class the same as changing a fitting.

Interestingly I didn't see the problem when using the more expensive Phillips bulbs, in bathrooms. Other bulbs, or even Phillips in other locations, I did. Maybe the bathrooms had a better class of transformer to begin with.

Those pink Ultra70w run our 5w MR16 LED's fine too, one bulb on each transformer.

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heylinb4nz

656 posts

Ultimate Geek
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#1273506 30-Mar-2015 16:06

Ideally you need to be using 12W MR16 LEDs if you want to get anywhere close to 50W halogen equivalent lighting. Transformer wise most Halogen electronic transformers are rated at 20-60W. We got lucky and our house at Eurolite 10-60W which run our 12W MR16 just fine.

Cheapest transformer ive found that does 10-60W was at JA Russell was around $7.

Or you can try and find house lot of second hand Eurolite ones.

aros71

122 posts

Master Geek

#1273508 30-Mar-2015 16:10

heylinb4nz: Ideally you need to be using 12W MR16 LEDs if you want to get anywhere close to 50W halogen equivalent lighting.

I've found the Philips 5.5W ones subjectively to be equivalent to 50W halogens.

The box lot of 3.5W ones I got from AliExpress are approximately equivalent to a 20W halogen.

I have never seen a 12W MR16 LED... do they even exist?

In the end, I just started replacing transformers through the house, it's just a slow process as pretty much all the lighting in my whole house (4bed 3bath 2storey) is MR16 12V halogen. Wondering what the hell they were thinking. There's about 70 lights at a rough count, including effect lighting outside.

Vaguely ridiculous

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