I had bought 20 pcs MR16 LED track lights about 18 months ago. They were from main land China E-bay supplied. The LEDs are 3w 12v (20w eq) bright white and we have a lot of track lighting in the house and could use another 20 pcs. We really like them. So far lost 3 LEDs I'm sure its the little printed circuit LED driver. $400.00 for the house hold lighting seems high but there is a pay-back and the halogens needed replacing often and I was looking forward to life-time LED lighting. Getting the ladder out to change a bulb then next week another right beside damm.

Randen

I have four LED bulbs in my house (and more in my car), recently purchased. All my other bulbs are CFL. I still have CFL bulbs that are probably 12 years old. I prefer the CFL at this stage in the market's development because the selection of LEDs is smaller, the prices are wicked-high, the power-savings are not so much better than CFLs that they justify the pricing. The four LEDs I bought were for track-lighting applications for which I have never seen CFLs, and the power savings was significant when replacing halogen bulbs that fail frequently anyway. I like the LEDs I have, but I can't comment on reliability since they have only been in use a couple months.

My preference would be with LED since they are either on or off. I like CFLs because of their low power consumption but I don't care for the gas inside of them. Also, CFLs in my mind, don't like cold temps and don't like on/off cycling. LEDs on the other hand, are more tolerant of either.

In regards to dimming LEDs, I was under the impression that an electronic dimmer was to be used with them rather than a resistive dimmer. To expand: the electronics would be PWM which would dictate the length and duration of on, and of off, times. Lesser "on" times would result in less "total" light output even though the LED is on 100% during the "on" times.

The Lutron DVCL dimmer switch is designed to work with LED's, it also has an adjustment on it so you can tune in the LED you have, of course you also need to use an LED that works with dimmer switches.

So far it seems like the people who have had LED's fail are the ones who are going for the cheapest LEDs the can find and that there aren't any brands to avoid because they are sold in blank boxes, am I right? I of course have bought some LED's that came in blank boxes my self, but I bought them from people who get samples, then test and sort to figure out what is the best to sell and if I have one fail then I call up and talk to a real person, but then again I've never had one fail and I have them in nearly every room of the house.

I ran tests on Standard / Fluorescent / CFL / LED / Super-flux LED (all 12V)

Solar Lighting Designers dream is all I can say about the new 3W / 10W or Clustered LED Floodlights ... well made, Very Low Power and Very Bright.
Great on cars but more to the point Superb in you home where a 10W External (Alluminium Body) getting as hot as a cup of tea !! Safe / Safe / Safe . .

BY THE WAY ... Its always interesting to see that people look at LED Technology for 240V and 110V Mains only... hmmmmmm

Think of your house as a car, with many rooms, where each room has 1 x 12V light.
Each 12W Light is supplied with 12Volts from 1 x 12V Battery.
Youtube it / Google it / Study it / build it .. The implications are that your initial investment, will save you much money over possibly 20 years +

Look at Off grid Cabins etc where they double up on Batteries to create 24V and 48V systems. (The only reason for this is to deliver a Specified Load over a specified distance) - Simple OHMS Law - secret to understanding that is learn Basic Electronics Theory - and play around with the 3 things that mean something - Volts / Amps / Resistance (The Resistance is the Cable Length and diameter)
Watts is the Power so 10W divided by 12Volts is ?Amps ... get it
Only worry about 12V / 24V / 48V - Only Design for 10W & 15W LED Lights - There are Maximum cable Length Charts on the Net free - example .. a 15W Light on a 12V System must not be connected by a Cable that is Longer than 6 meters @ .75mm Diameter - Why - plug the numbers into an OHMS Law equation to see why .. FUN !!

A couple of years back, I took my bed room reading lamp off-grid, using some car LEDs.

http://ecorenovator.org/forum/lighti...mps-house.html

It's still being used nightly and it works okay. But I've noticed the light is a bit on the blue side (colder?).
It's not the warm light that we get from our 120Vac LEDs used around the house.

The diameter of the wire wasn't considered. I used a small size wire, since the run was only about 12 feet.
The power loss of the wire that short is so low, it wouldn't be noticeable.


Actually, the 100 ft run from the little PV panel on the tracker is about 2 ohms!
Here's a pic of the panel used for the reading lamp. (with charge controller and small SUV battery).
http://i46.photobucket.com/albums/f1...testingSBC.jpg
But, so far both of my old car 12V PV charged batteries are working fine using a small wire gauge.

Ok .. but remember if your gauge is the wrong diameter for the Load Current then there is a risk of heating up the cable !!

So the rules are this :-
find out the power that your Light uses.
For a 10W 12V light the OHMS LAW SAYS P/V = A so 10/12 = .83A = 830mA

Nearly 1 Amp which means you can have 9 meters of .75mm diameter Twin & Earth with that light at the end of it, without a problem.
Double the Diameter of the cable then you can double the length.

This is costly over long distance so everybody ups the Voltage instead to reduce the Diameter of the cable over a long distance and hence reducing the cost of the cable. :)

I have both my 500 & 800 watt PV arrays using 2mm cable. IIRC, each of those cables is about 120 feet long.
There are some losses, but since they are less than 1% of the total power, there isn't any profit in worrying about it.
Especially with the price of copper..

When I built my office (partition walls around a previously open second family room), I opted for LED lights, as no lighting was in the room prior to that. I used strings of LED modules (4 SMD LEDs of type 5050 per module, 10 modules per fixture, 2 fixtures). They consume around 7W per fixture according to the LED's specs, and output about 24 lumen per LED for a total of roughly 1000 lumen per fixture (or roundabout the same as a 15W CFL).

The fixtures are simply strips of 1/8" plywood, painted white, with the modules mounted on them. I coated a strip of acrylic of the same size with frosted glass spray and bolted it with 1" distancers to the plywood, then screwed the whole thing to the ceiling.
When I built the partition walls, I mounted a 48W LED driver to one of the studs and ran wiring from an existing outlet in another wall to it - the light switches now switch 12V directly, which made running the wiring for the lights really easy (the low voltage stranded wire I used is flexible and easy to pull around corners and through holes).

In addition, I've got a flexible strip of the LEDs under the shelves which are mounted to the wall above the desk, for a total of about 25W of lighting equivalent to about 50W worth of CFL bulbs. The light output is quite good already, but I'm considering adding another two fixtures; I've mounted the existing two relatively close to one of the walls, so the other half of the room tends to be a little dark.

The LED modules can be had for as little as $20 for a string of 20 of them, which makes them cheaper than pretty much any commercial solution, and since all of them run off the same transformer, losses are likely less as well. LEDs are usually rated at 50,000 hours, which is 5 years of continuous run time or over 30 years with our normal usage - which means that most likely, they'll last about as long as I will ;)

I'm going to convert the rest of the house to similar solutions. The kitchen is next, where I've currently got three circular fluorescent fixtures - at 75W each, yikes!