LED replacements for Halogen downlights - ISSUES

The greenest watt is the one you don't have to create. Energy efficiency is the low hanging fruit of greening our homes. Ask your questions or post your energy efficiency tips in here!

Re: LED replacements for Halogen downlights - ISSUES

Postby steve » Fri May 14, 2010 2:00 pm

I have been surprised at the comments about the older transformers still using 10W when driving a single LED downlight. I have migrated some of my downlights to LED's and had planned to connect multiple LED's to each transformer. However, when I measured the power being consumed by the transformer when driving a single 3W LED it was approximately 1W. So given there appeared to be no, or at least very little, efficiency improvement I have connected each LED to its own transformer.
steve
Solar Supporter
Solar Supporter
 
Posts: 2
Joined: Fri May 14, 2010 1:53 pm

Re: LED replacements for Halogen downlights - ISSUES

Postby bradley.jarvis » Mon May 17, 2010 11:13 am

That is a 75% efficiency (3W light -there is some heat here too, 1W heat from transformer). If you were running a 50W hallogen that would be 50W for light (lots of heat loss) and 10W for the transformer(more heat), so roughly 83% efficient. I am assuming since the wattage figures are given in whole numbers then the accuracy of the measurement is not very good. We are running our 12V led downlights directly from our 12V battery bank, no loss in transforming the power and very little loss in cabling (not particularly long runs with low load).

Thanks, Brad
Living off-grid and loving it!
bradley.jarvis
Solar Evangelist
Solar Evangelist
 
Posts: 80
Joined: Tue Sep 22, 2009 10:46 am
Location: Australia, Victoria, Trida

Re: LED replacements for Halogen downlights - ISSUES

Postby steve » Mon May 17, 2010 11:34 am

Hi Brad,

The tool I used to measure the power usage is only accurate to +-5W. I had to use statistical analysis with many readings to get the ~1W figure. My error bars are still in the order of 1W.
So, yes, the efficiency at approx 75% is not good but the quantum relative to halogen is superior. I gather from your tag line you probably have a solar charged battery array and 12V wiring in your house. Is there a reason you don't feed this into the grid? I have always assumed this would be more efficient than local battery storage given the losses associated with that storage.

My grid connected solar array installation started last Thursday which and, coupled with the transition to LED lighting, should bring my electricity footprint back to zero.

Cheers
Steve
steve
Solar Supporter
Solar Supporter
 
Posts: 2
Joined: Fri May 14, 2010 1:53 pm

Re: LED replacements for Halogen downlights - ISSUES

Postby gully » Mon May 17, 2010 3:07 pm

Whilst you're right that 1 watt would not be a big deal, especially if you're saving 46 watts per globe, from a maintenance point of view i'd be hooking sets of downlights to a single transformer simply because you can, and it's cheaper to replace one transformer than 2, 4 or 6. You could keep the unused transformers as spares...

Can't remember if the transformers are wired such that they are 'always on' or only active when a light is turned on. In the former case, each transformer becomes a phantom load 24/7. If you're not sure about it's wattage, you could connect a known wattage globe (eg. 50 watts) then take a reading from the transformer, disconnect the globe, take another reading. Average the difference (subtract 50 from the first reading) to get a more accurate measurement.

brad.jarvis: I realise you save power staying in 12v mode but your battery bank is likely to be around 75% efficient, too =)

Of course 240v downlights don't use any transformers, so they would have less carbon footprint by design (less wiring, maintenance, power loss).
------ --- - -- -- - -
Network/Retailer: SP Ausnet / Red Energy (EM 1200 smart meter)
PV: 10 x 175w Suntech (1.75kW) panels and SMA SB1700 Inverter
SHW: AAE Solar Gas Storage 250L 30 tube
Tank: 10,000L Tankmasta w/ Rainbank 2 into laundry/toilet
gully
Solar Evangelist
Solar Evangelist
 
Posts: 89
Joined: Thu Sep 24, 2009 2:05 pm

Re: LED replacements for Halogen downlights - ISSUES

Postby 737 pilot » Thu May 20, 2010 11:38 am

I had 12 halogen downlights in the house- only a very few compared to some houses!

These things are an environmental disaster in so many ways, including safety. Why were they ever allowed in houses?

I have read this topic with great interest, but am still debating where to go and what to do with my lights. Here is what I have done so far:

Group 1. Front entry, no dimmer. WAS two 50 w Halogens.
..................NOW One 50w halogen (wide beam- lighting the entry plus a large picture on the wall) and One 3w LED recently from Woolies, about $12. The 3w LED is not bad- warm white and close to equivalent to a 20w Halogen.
So now 53w instead of 100w. Not sure what to do here- I do need a bright light for the picture.

Group 2. Dining area. WAS six 50w halogens :o , controlled by a dimmer with just one switch, all on or none. :(
.......................NOW Two 50w wide beam halogens, lighting pictures on the wall, and the rest 20w halogens.
So now 180w instead of 300w My plan here is to try to get a second switch-wire down the wall cavity and have a bit more control. I will likely try four 3w LEDs (un-dimmed) over the table with just the dimmable 50w Halogens for the pictures- a 20w Halogen or equivalent is just not bright enough for these. That way we can often live with just the four LEDs ie:12w (plus any transformer losses).

Group 3. Living room, separately switched with three circuits, were dimmable. WAS six 50w Halogens. :o
........................NOW different light fittings with 22w CFL downlights, no longer dimmable.
So now 132w instead of 300w. We actually very rarely use more than two at once so more typically 44w.

Any comments or suggestions? I hate Halogens and would love to replace my 50w halogens with something better. I have noticed some 20w halogens are much better than others, but can't seem to work out which are the good ones when I go to buy more.
Cya
Dave
Xantrex 2.8Kw inverter.
3.6kw of panels.
Mad keen on improving energy efficiency of the whole system and house.
737 pilot
Solar Fanatic
Solar Fanatic
 
Posts: 28
Joined: Tue May 11, 2010 1:05 pm
Location: SE Qld

Re: LED replacements for Halogen downlights - ISSUES

Postby gully » Thu May 20, 2010 12:16 pm

I've got 4 x 20w halogens (one switch) in the bathroom and 5 x 20w in the kitchen (two switches 3/2). I'm hesitant to go to led until the prices drop and quality stabilises, and I want the ability to dim the bathroom lights.

Long-term I think 240v is the way to go - I find 20w globes give enough light compared to a 50w.
------ --- - -- -- - -
Network/Retailer: SP Ausnet / Red Energy (EM 1200 smart meter)
PV: 10 x 175w Suntech (1.75kW) panels and SMA SB1700 Inverter
SHW: AAE Solar Gas Storage 250L 30 tube
Tank: 10,000L Tankmasta w/ Rainbank 2 into laundry/toilet
gully
Solar Evangelist
Solar Evangelist
 
Posts: 89
Joined: Thu Sep 24, 2009 2:05 pm

Re: LED replacements for Halogen downlights - ISSUES

Postby Gordon-Loomberah » Thu May 20, 2010 2:25 pm

737 pilot wrote: I have noticed some 20w halogens are much better than others, but can't seem to work out which are the good ones when I go to buy more.


Decostar halogens from Osram deliver quite a bit more light per watt consumed, compared with other regular halogens. I have one for a bike headlight- vastly more light than 4 X 3W Cree LEDs... although the Crees use less power and weigh less, so get the most use.
http://gunagulla.com Loomberah weather and astronomy including live solar radiation intensity and UV + Gunagulla aquaponics, organic eggs and cherries
User avatar
Gordon-Loomberah
Community Moderator
 
Posts: 5748
Joined: Thu Sep 24, 2009 9:41 pm
Location: Loomberah NSW Australia

Re: LED replacements for Halogen downlights - ISSUES

Postby karlajensen » Sun Jun 20, 2010 11:38 am

OK time for me to chine in....
I lashed out and bought 6 GU10 warm white 3x3W CREE downlights from ebay (dimmable) at about $30 each + a few bucks in post.
They are excellent and I chose to use them in the kitchen and they spend most of their time on during the evening. Well worth the investment, happy with the output vs 50W halogen (probably about 75-80% as bright)
8E + 8W + 8Nth Garage CMS2000-1 with ~4500W in 3 strings of 8.
Fronius Galvo 3.0 inverter with ~6.6kW panels
12x ZNShine + 12x 180W Solarfuns both NW + ZNShine 12x190 facing SE.
Edwards Solar Hot water


Luck Favours the well prepared.
User avatar
karlajensen
Solar Crusader
Solar Crusader
 
Posts: 1346
Joined: Tue Oct 13, 2009 9:30 am
Location: Perth

Re: LED replacements for Halogen downlights - ISSUES

Postby zzsstt » Tue Jun 22, 2010 12:03 pm

karlajensen wrote:OK time for me to chine in....
I lashed out and bought 6 GU10 warm white 3x3W CREE downlights from ebay (dimmable) at about $30 each + a few bucks in post.
They are excellent and I chose to use them in the kitchen and they spend most of their time on during the evening. Well worth the investment, happy with the output vs 50W halogen (probably about 75-80% as bright)


Thats great. At 19c a kWH, running them for 5 hours a day, each LED will save you about 1.9cents per day over a 30W 12V Osram. So you're saving energy, only losing about 25% light, AND you'll pay off the additional capital investment in only 3.5 years or so, assuming they last that long!. Sounds like a bargain..... ;)

Of course a single 20W T5 fluoro would replace all 6 halogens, use a third of the power of the 6 LEDs, cost less than the 6 LEDs, produce as much usable light and (probably) last just as long......
zzsstt
Solar Crusader
Solar Crusader
 
Posts: 1296
Joined: Fri Oct 02, 2009 2:27 pm

Re: LED replacements for Halogen downlights - ISSUES

Postby Aussie scotty » Sat Dec 18, 2010 7:03 pm

karlajensen wrote:OK time for me to chine in....
I lashed out and bought 6 GU10 warm white 3x3W CREE downlights from ebay (dimmable) at about $30 each + a few bucks in post.
They are excellent and I chose to use them in the kitchen and they spend most of their time on during the evening. Well worth the investment, happy with the output vs 50W halogen (probably about 75-80% as bright)


Yeh I did the same thing,lashed out and got 25 3x3 cree downlights on Ebay, I ended up paying $17 each so I was really happy with that. I just worked out my power consumption when the Country Energy guy came around to read my metre,I've jumped from 17Kw/day down to 13Kw/day and they haven't been in for the full quarter.
I've tried some other LED's from Hong Kong which were 4W, although they are half the wattage of the cree, they are more than half dimmer than the cree too, the cree's are the way to go
Aussie scotty
Solar Supporter
Solar Supporter
 
Posts: 4
Joined: Tue Oct 26, 2010 11:18 am

PreviousNext

Return to Energy Efficiency

Who is online

Users browsing this forum: No registered users and 1 guest

new solar power specials