Jump to content

Recommended Posts

Not cheap to change all the lights to LED, but apart from the long life is there a noticeable change in use of electricity if I change them all?

Anyone with observations?

Link to post
Share on other sites

What are you using now?

 

If incandescent, a noticeable change in your electric bill.

 

If fluorescent or compact fluorescent, a much smaller change. More noticeable is the lack of delay in reaching full brightness in the winter over compact fluorescents.

Link to post
Share on other sites

Fact is that LEDs use a transformer. Each tranny can cope with a lot more lights than a transformer for Halogen lights.

 

The really important thing is that LEDs tend to last around 30 times longer than halogens.

 

We have replaced all out halogens with LED downlights, no actual numbers but gut feeling is that they have saved around 5% on power bills.

Link to post
Share on other sites

Metabo-San, I don't know the answer to that....could you perhaps show me the Japanese writing for each of those?

 

Thank you.

Link to post
Share on other sites

Fact is that LEDs use a transformer. Each tranny can cope with a lot more lights than a transformer for Halogen lights.

 

The really important thing is that LEDs tend to last around 30 times longer than halogens.

 

We have replaced all out halogens with LED downlights, no actual numbers but gut feeling is that they have saved around 5% on power bills.

You can get mains LED lights that do not require a transformer an are a direct replacement for standard light globes.

Link to post
Share on other sites

Yeah, they have a built-in transformer, so they negate the advantages of having more than one light on a tranny.

Link to post
Share on other sites

Fact is that LEDs use a transformer. Each tranny can cope with a lot more lights than a transformer for Halogen lights.

 

The really important thing is that LEDs tend to last around 30 times longer than halogens.

 

We have replaced all out halogens with LED downlights, no actual numbers but gut feeling is that they have saved around 5% on power bills.

 

the latest LEDs have their transformers inbuit so you can change them like a regular light bulb. The price of LED lights is the downer right now.

Link to post
Share on other sites

Metabo-San, I don't know the answer to that....could you perhaps show me the Japanese writing for each of those?

 

Thank you.

 

Incandescent bulb: 白熱電球

 

Fluorescent lamp: 蛍光灯

 

Compact fluorescent: 電球形蛍光灯 or 電球型蛍光灯

Link to post
Share on other sites

Every transformer is thermally inefficient. So, the more of them you have, the more electrickery you are using to heat the transformer. Heating the transformer uses power that is not available for lighting.

 

Best option is to have a single transformer and run 12V wiring throughout the house. I know that's easier said than done, but it is much, much more efficient in terms of power usage.

Link to post
Share on other sites

I heard that its easier to dim LEDs. I gave up on the idea of dimmer switches in our place because we have CFLs. I wasn't bothered about LAN cables, but I would have liked dimmable lights. Instead we just have table lamps.

 

There was an architectural trend in Japan toward smaller E17 fittings, but you can't get powerful LEDs in that size. Avoid that size if you can.

 

I don't mind CFLs in general, but am thinking of switching out the ones directly above our dining table because I always seem to get weird, difficult to fix colours in the photos I take at the table. I've seen articles online that suggest the flickering of flourescent lights can affect how different parts of the image are exposed at certain shutter speeds.

 

http://johnbdigital.com/lenses/fluorescent/fluorescent_lighting.php

Link to post
Share on other sites

If you did that JA, then the transformer would be powered even when the lights are switched off - 1 per room is a better option, that way the transformer could be after the light switch - so if you only have a few lights in each room (e.g. a bedroom light, then the mains powered LED lights will be a better option.

Link to post
Share on other sites

NO!!! Unless there is a flow of electricity in the secondary of the transformer, there is no flow in the primary, and thus no heating.

 

Besides, each individual tranny is (say) 40% efficient, that makes 60% of the electric power being consumed to heat the transformers. A single, large, transformer is likely to be much more than 40% efficient, so it creates less heat to light the whole lot of LEDs than a whole lot of smaller transformers.

Link to post
Share on other sites

In theory, you are right, but in reality, you will find that every transformer will have a small current flowing. To be technical, for a transformer coupled device the loss depends on what is called the leakage inductance of the primary coils of the transformer. This is essentially the amount of magnetic flux in the coil that is not connected into the secondary.

Link to post
Share on other sites

So ... how about the differential efficiency of the larger tranny wrt a bulk lot of smaller ones?

 

My information is that a large transformer would be more thermally efficient than (say 30) smaller ones.

 

And, even if there's a small leakage, the heating effect is not likely to be significant, surely.

Link to post
Share on other sites

Its probably not significant, but then I wouldn't imagine that having many smaller transformers would have much of an effect on your overall power bill - particularly in bedrooms, bathrooms etc where the lights might only be on for 1/2 an hour a day, compared to say your living area or office where they might be on much longer periods of the day. Where it will cost you more is in installation - it may be necessary to use heavier gauge cable for your lighting circuits - however if you are going with LEDs this may not be much of an issue either, as generally lighting circuits are designed around conventional incandescent lights, and LEDs use less than a 10th of the energy of these.

 

I did some calculations for a commercial customer who had a salesman trying to get him to change his fluoro tubes for LED replacements - this was about 18 months ago, but at the cost of the LED tubes, taking into account the expected life of the fluoros vs the longer life of the LEDs, the energy savings were not enough to cover the higher cost of the LED tubes.

 

In a home situation, I would expect it to pan out much the same - if you are currently using halogen downlights or incandescent lights, change them for LEDs, but if you are using compact fluorescents, then stick with them - at least until the price of LEDs comes down, unless you want to be able to dim your lights, or like Mr Wiggles you are having issues when you are taking photos or video.

Link to post
Share on other sites

One advantage of your method JA, would be, that here in Australia at least, you would be able to carry out any of the 12V electrical work yourself - I would not recommend this if you are not 100% certain of what you are doing though - a short circuit on the 12V side of the transformer could still cause a fire.

Link to post
Share on other sites

Basically a transformer is a voltage changing device.

 

You have a primary core and a secondary core.

 

They are used when a different output voltage is required from the input voltage and are often used for lights for this reason.

Say you have 100v going in, but you only need 25v coming out, then a transformer will be used for this.

 

The difference is input voltage and output voltage is determined by the number of turns on the two coils (primary) and (secondary).

 

So less coils on the secondary or outgoing side will mean the voltage will be stepped down, the more coils the higher the secondary voltage will be.

 

The amount of efficiency will depend on the deference between the input and output voltage and the amount of work it has to do, this is where the build up in heat comes from.

 

In theory a bigger transformer will give off more heat than a smaller one, but then a larger transformer usually can handle larger loads, so small loads on a big transformer may give off less heat than a smaller one.

Usually voltage leakage will be less from a larger so they tend to be more efficient.

 

So you would be better off using a few larger transformers rather than lots of small ones as this would actually use less electricity.

 

Another even more efficient way would be to use one transformer big enough to handle the load of all the lights, and then add a capacitor to each light.

As capacitors charge and store electricity this would make the transformer even more efficient as any leakage would be compensated by the capicitors, and as they store electricity less work is required from the transformer, which will bring down the amount of electric required, thus making the electric bill cheaper.

Link to post
Share on other sites

In a home situation, I would expect it to pan out much the same - if you are currently using halogen downlights or incandescent lights, change them for LEDs, but if you are using compact fluorescents, then stick with them[...].

 

That is what we are doing. Switched all incandescents to compact fluorescents several years ago, and will gradually change those to LEDs as they die. Only just replaced the first two recently.

Link to post
Share on other sites

Here's a duh question.

Back home my parents seem to have long thin stick like things in their lights and they aren't 100% power when first turned on. What's with that then?

Are the bulbs you buy here instant?

I'm guessing perhaps when they bought them they were either new and/or cheaper versions.

Link to post
Share on other sites

I've probably switched to being about 70% LED. Quite often the hardware stores have specials on LED bulbs so as the fluoro bulbs die off I've been replacing with LEDs.. I hate the fluoro lag....messes with your head.

Link to post
Share on other sites

I reread somewhere that the power consumption ratings are laboratory and in no way can you get it in real application.

 

The step down transformers are also wasting lecky by heat etc. which is all true, but the consumption ratings for the equivlent lumens of say, 3W LED being = to 11W CFL = to 60W bulb is not true.

 

LED would only save you 10% on CFLs but the price outlay is substantial.

 

I didn't want to believe the article, but it has had me thinking.

Link to post
Share on other sites

The big saving is in the lifetime of the units - a LED unit lasts up to 20- times as long as a CFL, and that's significant!

Link to post
Share on other sites
×
×
  • Create New...