After my last post, I have quite a few updates, which deserves a new separate post.

#1 For my home, it was strangely decided to buy LED downlights for general lighting(not for reading or work that requires concentration). I didn't have knowledge of this and the downlights unfortunately was bought from a shop in Madurai with poor quality. In my experience in window shopping at Madurai for LED lamps earlier, I had found the lights to be of pathetic quality. Outraged, I demanded that all the lamps be first rectified and only then used. Below is a disassembled down light:

There were two problems - poor LED quality and low constant current driver output. The LED had a small die and poor luminous efficacy and the driver's output was 160mA when it should be giving 350mA.

I bought many Edison 146 lumen 1W LEDs and drivers from Precious lighting Solutions in Ritchie street, Chennai. I found out that one of the 146 lumen LED was equivalent to 3 nos of the pathetic ones. For most of the lamps, I replaced three poor quality ones with one good quality one as the brightness was enough. Since I'm going to setup solar installation for my entire home, every watt of power saved is critical. I didn't replace the driver for all downlights though. Downlight used for lighting staircase required high brightness and hence I replaced both there. For rest, I used the original driver and the one 146 lumen LED, which was enough. I don't know how much was the cost of the original focus lamp was, but refitting a downlight cost me Rs.120 for the 3W constant current LED driver + Rs.150 for 3 LEDs, totaling Rs.270.

The problem I think is that most shopkeepers in Madurai didn't know anything about LEDs and hence they were probably conned into buying it in the first place. Whereas, in Chennai, the shopkeeper is reasonably knowledgeable and hence knows what he is buying.

#2 I bought an 18W LED tube for Rs.1600. The total lumen output was mentioned as 1600 lumen by the shopkeeper. The brightness was considerably more than the 36W LED tubelight that I mentioned in earlier post. The light, though not spread 360 deg evenly like a FTL because the back side of it was made up of aluminum heat sink. But it was good enough, unlike my attempts to assemble tubes using short aluminium heat sink in earlier post. It was almost twice as bright as my other LED tube, which consumes 12W and cost Rs.1100. After this I spend a glut and bought 4 such LED tubes.

My brother didn’t like the LED tube as he feels that spending 40 times the amount of a normal tube (Rs.40 for T8 Fluorescent tube) for 50% decrease in power consumption is not economical, considering low domestic tariff. Also, LED technology is improving day by day and we’ll soon have better technology tomorrow. But I pointed out that since we’re going solar soon, decreasing the power consumption helps considerably as it reduces the size of the solar setup. But for commercial usage, it would require 16000 hours in operation to justify for the cost of LED tube over fluorescent tube at commercial rates. Also, I now feel that 15W(Rs.1300) from the same shop would have been enough as this is considerably brighter than a 36W FTL.

These tubes come with a one year warranty, but I do hope it lasts for 7-10 years.

#3 I assembled 4 LED 12W bulbs too recently. I used 146lumens/W LEDs to assemble. But before assembling, I read this concerning report about LED lights which says that blue light from LEDs can damage the eyes on the long run. The solution, apparently was to use warm white lights. Hence I assembled 12W LED bulbs using 9*1W cool white LEDs and 3*1W warm white LEDs. The light in the end had a yellowish tinge instead of a bluish one. The bulb is brighter than a 25W CFL. Though unlike a CFL or a FTL, the light is not very much distributed. Two of these bulbs will soon be operated at atleast 12 hours a day, thereby subjecting them heavy duty. It cost Rs.950 per bulb to assemble.

My calculations show that it will have be used at 12 hours per day for 3 years to be economically benificial at commercial rates of Rs.7/KWh over a 25W CFL. One problem was that only a Edison screw type base(E27) was available for the bulbs. These base cap holders are uncommon in India.

#4 From 1-Feb-13, I had switched on an 1W LED in order to possibly determine the durability and hence reliability of the LED drivers from Precious Lighting solutions. As of 14-july, the LED driver has operated successfully for 3900 hours. That translates to 2 years at 6 hours per day. Hopefully the driver will last much more than that.

#5 There is a 400W halogen in operation at my mother’s hospital and it needs to be replaced. To replace it, I would need 3*50W LED flood lights, according to a shop in Chennai. My calculations suggest that I’d save Rs.2375 for the first two years and Rs.15150 for four years. Here’s how