12v LED dimmable supply

[Weasel]

I want to replace quite a few gu5.3 50w downlights with led. I don't want to replace all the fittings, there are too many.The replacement 12v led has no driver and drops In fine, Problem is that it has to be dimmable and the existing driver will vary the voltage not the current. So I'm looking for a drop In replacement driver that will use the same dimmer switches if possible. Any recommendations?

It needs to handle about 80w

[Gerald_db]

My experience is that 12v dont dim well or smoothly and far more successful to change to 220v leds.

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[Guest]

Pal of mine really likes his dimmable downlighters. First round he got the 12v bulbs with nice transformers, worked lekker for many years.

Then he went solar on his lights and found the transformers are wasting a lot of power. 

He ripped it all out, now all are 220v LED downlighters and no transformers. Much more efficient and works betters as Gerald says.

[Weasel]

yea i get that, you will have losses over the wire lengths, but given the choice of changing 189 fittings or just the drivers.... besides a modern high quality dimmable led driver cant be that inefficient, and a 230V Led still has a driver built in, the only difference really should be cable losses.

[___]

4 hours ago, The Terrible Triplett said:

Then he went solar on his lights and found the transformers are wasting a lot of power. 

That's odd, for two reasons. The first is that your good old iron transformer is very efficient, above 90%. The second is that I have the same setup, around 30 down lights, all with transformers, and I tested one on the Efergy plug-in meter. With a 5W lamp on it, it draws 6W on the AC side. Now this is hardly a very accurate measuring device, but it gets the power factor more or less right (the LED with transformer combo has a rather terrible power factor of 0.2), so all in all, that's a loss I'm willing to accept.

 

I don't know what it will be like with the so called "electronic" transformers. Definitely no problem with the old iron ones.

 

Check out a guy called "LED Select" on BidOrBuy. He sells constant current drivers and stuff.

[Guest]

Have no idea why.

I had fluorescent tubes in the kitchen, 2 foot ones, 4 of them about 20w each on transformers in one square feature fitting.

So one day I took them all out, leaving the transformers in place for manual said I can. and inserted one 9w LED tube first, to see and "feel" it.

For months I could not understand why my batts are draining so fast. One evening, quite accidentally, just the 9w kitchen LED tube on in the entire house, I saw that the 9w kitchen LED tube was drawing about 209w. WTF!

Turns out the 4 transformers, very very old ones, even though 3 of them had nothing connected to them, where still consuming 50w each.

I promptly had the unit rewired, having removed all the transformers. Now I see 9w used - SWAMBO being ok with one 9w instead of 4 x 9w LEd tube - no, I did not bully her.

[Weasel]

58 minutes ago, The Terrible Triplett said:

Have no idea why.

I had fluorescent tubes in the kitchen, 2 foot ones, 4 of them about 20w each on transformers in one square feature fitting.

So one day I took them all out, leaving the transformers in place for manual said I can. and inserted one 9w LED tube first, to see and "feel" it.

For months I could not understand why my batts are draining so fast. One evening, quite accidentally, just the 9w kitchen LED tube on in the entire house, I saw that the 9w kitchen LED tube was drawing about 209w. WTF!

Turns out the 4 transformers, very very old ones, even though 3 of them had nothing connected to them, where still consuming 50w each.

I promptly had the unit rewired, having removed all the transformers. Now I see 9w used - SWAMBO being ok with one 9w instead of 4 x 9w LEd tube - no, I did not bully her.

oh yea this is a very common mistake made, the ballasts needs to be disconnected, some draw more power without a load. i remember removing tubes in my flat when i was a student with the idea that it used less power. no no no doh, it just doesn't. Your ballast effectively becomes a heater and pisses the power away.

[___]

AAaah, don't confuse the ballast with a Transformer... got it :-)