Halogen to LED Issue

[racclarkson@gmail.com]

Someone, I know, has had this happen to them.

I am replacing my 20 watt 12 volt halogen bulbs with JC G4 12V-24V LED 4.5W 5730 LEDs. On a four or more fixture circuit, no problem. On each of (3) three fixture circuits, the LEDs give quick flash--that's it, no light. If I replace just one of the LEDs with one of the old halogen bulbs then everything lights up. Having recently replaced one of the 110v to 12 volt transformers, I know all three circuits are independent of each other and there are no breaker trips.

So what's up?

IMG_9109.JPG

[sgharford]

Had something similar happen in my jeep when I replaced cabin lights with LED. There was not enough resistance in the new LED light bulb so the canbus would not recognize there was a bulb in there and simply would not supply power. Had to find an LED with more resistance, that solved the problem.

[Cricket]

Had something similar happen in my jeep when I replaced cabin lights with LED. There was not enough resistance in the new LED light bulb so the canbus would not recognize there was a bulb in there and simply would not supply power. Had to find an LED with more resistance, that solved the problem.

Yep, not enough load for the circuits in the transformer to kick in. What size transformers did you install, wouldn't need much for 3 of the led bulbs?

[racclarkson@gmail.com]

Thanks guys, makes sense. The transformer I just replaced was 75 watts, so that's way more than 3 of these will pull. Since I posted, my hallway four light circuit quits after 3 or four mins, same symptoms. My VIP has three on a circuit and it's been working continuously for an hour, but with one halogen in place.

Everyday I learn something new. I'd like a day off now and again.

[tonytrakovich]

Did you replace the transformers with led drivers or regular wire wound transformers? Led are DC devices and should be run by a led driver that supplies DC voltage. LEDs are also polarity sensitive. Hook up wrong way and they don’t work. The dimming in also different on led. AC devices just control voltage. LED dimmers actually pulse (very fast) to dim. LED drivers will not care about minimum load. I know some led are rated for ac and dc voltage. I have found that running them on ac voltage shortened their life.

[davidwigler]

These work great:

https://store.marinebeam.com/hattera...-dc-converter/

[racclarkson@gmail.com]

Thanks, as I mentioned my input is AC.

[Pascal]

Make sure the transformers are 120 AC to 12 DC. Some are 120 AC to 12 (or 24) AC and some LEDs will not work on AC.

[Boatsb]

I just pulled 2 120 volt to 24 volt a.c. transformers from a customers lighting circuits.

A.c. is not good for less. Also a 75 watt transformer should be fine if it's compatible with the led lights but seems that lnes not.

Cars have monitoring of dc circuits to report lamp issues so when changing to led lamps they many times see it as a blown incandescent.

[Reefgeorge]

If you are working with raw LED chips or wafers then you need to calculate the proper power supply/driver which can be constant current or constant voltage. The basic point is to supply a regulated power supply to meet the needs of the LED chips but not burn them out, especially as they heat up and change resistance. I did this engineering work to make my own high output LED spreader light assemblies doing heat sink calculations, using Cree LED wafers and constant current drivers but I just happen to like this stuff. Most of you are probably not designing LED assemblies from scratch using raw components so this may never apply.

Next are integrated assemblies that can take a more common form of power as might be available in an existing socket so that the LED product is plug and play with 100 year old technology. One example are LED's that look like incandescent light bulbs with a std screw base for say a living room lamp. This product takes AC line voltage, rectifies it and supplies the correct regulated DC power to the basic LED elements/chips/wafers.

Then there are components like what we are talking about here. They are also most likely intended to replace an existing incandecent solution so they may be able to take AC power or may need DC power but are likely to have some elements on say the back of the wafers or boards that perform the regulation function. I can't find much on the LED "lights" being discussed here so I don't know what power source and range are acceptable but I suspect that it is an unregulated AC and/or DC voltage. What does the spec sheet say? Are there components on the back of the board or are these raw LED elements?


George