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LED Light Transformers / Power Supplies
#1
This is a sort of follow up on LED lighting that I posted here: http://www.computersense.co.nz/forums/sh...php?tid=60 and here http://www.computersense.co.nz/forums/sh...hp?tid=133

My entire house is fitted with LED lighting.
Most lights are downlights with a varying wattage (intensities) and the number and wattage of lights varies throughout the rooms in the house.
All of the lights use the same collective 1 watt (1W) CRE LEDs.
Example: In the dining room I have four 7W downlights, in the lounge I have four 9W downlights and in the kitchen I have four 12W downlights.

Each of the lights came with its own transformer which were installed with them.

I have had a number of transformers blow in the past and I decided that it was time to spend some money on one single and high-quality transformer per room and wire up a surge arrester to each to reduce both cost (of consumption) and time spent on replacing them.

I discovered a fundamental flaw...
To explain this I have to explain the light's requirements.
For a single 12W light using 12 x 1W CRE LEDS requires a 32 volt (32V) transformer - each individual LED requires around 2.66 volts to operate at full brightness (12 x 2.66V = 32V).
The LED's in each light are wired in series meaning that their voltage requirement is collective to the number of LEDs. IE: A 7W light needs 19 volts, a 9W light needs 24 volts and a 12W light needs 32 volts.
I have a combination of all of these and this is where the BIG issue comes in.

Only 12 volt, 24 volt and 48 volt transformers are readily available that provide sufficient amperage (grunt) to drive multiple lights of the same wattage.
For those who are "switched-on", you see where this is going don't you?

Getting a transformer from your local store for 12 volt and 24 volt is pretty damn easy.
While my 24 volt (9W lights) are easy to get the other 7W (19 volt) and 12W (32 volt) transformers are pretty much non-existent unless you purchase them individually (again one per light) from eBay (be careful to guaranteed) get CE rated ones.

I am pretty much stumped and dumbfounded over the non-existent standards of power requirements from manufactures.
Why can't ALL manufactures set the standard at 12 volts?
All it takes is a little intelligence in wiring some of the LEDs in parallel instead of series and using a resistor or two to compensate for odd numbers?
I'll answer my own question shall I? Manufacturing costs!

To solve my own problem, I have ordered a bunch of decent quality 24 volt transformers and I am busy modifying each light (parallel, series, resistance) to work in this range.
While I personally have the expertise to do this (as well as replace single LEDs in the lights when they fail) I fear that others are going to get caught out unless they do their own research and ask the right questions from their suppliers.

I am suffering from my own naïve decisions and trying to resolve my own problems - hopefully you learn from my mistake and don't have to fall into the pit that I had fallen into...
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#2
Would you suggest everyone get a transformer if they're dealing with these kinds of lights btw?
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#3
A lot has happened since my post here including advances in LED technology and huge price decreases.
I have now replaced all my LED lights with modern single LED CRE ones which have built-in power supplies.
LED lighting technology has now matured and I no longer have to battle with sub-standard voltages and poor reliability.
Having a single transformer instead of multiple transformers may no longer make sense as modern CRE lights (with built-in transformers) themselves are now cheap and reliable so it may not make economic sense to go through that mission.
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