I have a pair of black and silver 150W Halogen Torchier lamps(with dimmers) in my living room. I would love to be able to replace them with LEDs. I want to keep the lamps themselves, they match the rest of the house, and I am good enough with a soldering iron that I could probably pull off the conversion. However, I have seen threads and videos that indicate that I would need quite a few LEDs to match the light output of my two. I had some hope a couple months back that the Cree XT-E Whites might be a good option, but they seem to still be vaporware. Does anyone have any other suggests for leds that might work? I don't need to have the dimmer.
I have given some thought to the driver(in as much as I have looked around and found links to products), but i was going to wait till I figured out the load before delving into that.
I have not given a ton of thought to the cooling. I thought LEDs are more efficient when not driven so hard, so thought prehaps more LEDs at a lower current might be a bit better on the light/heat ratio. Beyond that, I was waiting to figure out the heat load before planning a cooling method.
Last edited by Caoster; 05-07-2012 at 10:34 AM.
Reason: Can't reply for some reason?
The XT-E definately has to be reflowed. Can't do it with a soldering iron. Have a look at XM-L but like LEDninja said think about a heatsink when designing LED retrofits. Also, have you thought about the driver and electronics system that you are going to need as well??
A double ended, 150watt halogen puts out 2400 lumens of light...according to the specs of an Ushio I looked up. However, the lumens drop quite a bit as the bulb ages, and doubled ended halogen bulbs have a massive fixture penalty. At worst you need about 2,000 lumens of 2700-3000 LED to match the halogen, and likely less. At 3500-4000k around 1500 lumens in LED land.
Assuming you want to keep the same color temp as the halogen 2,000lumens of LED is not that hard to do. A couple of 1,000 lumen Bridgelux, a Mean Well LPC 700 or 1050, and that's it.
The problem is thermal. You're talking about 20-30watts of heat to manage in a low profile package with almost no convection. You could easily mount the LED's to a 6" square low profile heat-sink and set in in the torche' and call it done, but the lack of vertical convection and the heat pooling up on the underside will be quite huge. You really need a radial heat sink to handle the heat passively, and at less than two inches high it would need to be the size of your out stretched hand to handle the heat. Yes, I've seen these, but they tend to be very, very expensive. I use Wakefield radial sinks for my 800-1000 lumen Bridgelux, but they are long and cylindrical. They wouldn't work quite right in a typical torche' light.
Which leads us to active cooling. Take that same 6x6" heatsink listed above, stick a typical 80mm computer fan on the under side, drive it at 3-4 volts, and that's more than sufficient to keep it cool.
It's also possible to use the torche' lamp itself as a heat-sink. Most of the housings are made of sheet steel, which is a rather lousy material and not something you can't glue 3watt XP-G's to, but it can be used if you mount the LEDs to aluminum first such as aluminum rod, and then mount it to the inside of the lamp. However, if your torche' lamp is oval shaped you might as well forget it. If it's 1/8 thick aluminum, why hell, just mount XP-G stars to the inside and away you go, but it's likely not.
Last edited by blasterman; 05-03-2012 at 10:55 AM.