Outdoor LED Power Supply Questions

[pete_c]

I think I am going to go with either a 65 or 100 watt 12VDC multiple DIN mounted power supplies.

For whatever reason I started thinking about polarity. (brain cramp - age thing)

I then realized that when I tested the LEDs there were no markings of polarity on them and I kept testing them just fine (they are all 12VAC/DC LED lamps) so it really doesn't matter.

 

[mdesmarais]

Good point. If one knows voltage drop and current, then one can calculate power. Power factor may come into play, if AC. One needs to know two of the following three: voltage, current, or resistance. I don't know how common it is to be able to measure current. I don't believe any of my meters can read current beyond the mA range, which would be too low for this measurement, I would guess.

Thus my comment about the slight loss of efficiency. For my own edification, do you know how much efficiency penalty one pays for operating at 50% versus 90%? Does the type of power supply matter?

Most meters will have a mA range and a 10A range. I went nuts and bought a clamp on ammeter last time I needed the capability. . .much more convenient. (any project that requires the purchase of new tools is a GOOD PROJECT! ;-)

The efficiency is dependent on the supply. A decent one will specify it- most good switchers are in the 75-95% range. I think the overhead is fixed- so if you are drawing 100W on a 100W max supply, the supply is using 110W, say. If you are only drawing 50 W, you are probably still using that close to that same 10W overhead. (overhead is losses in the diode and FET switches, power for the controller, etc)

 

[pete_c]

Ordered a 75 watt DIN mountable 12VDC PS today. It looks like the narrow one above.

I do have a clamp with my meter and never thought to try it.

The DIN narrow footprint will allow me to get a few in a little bit of space.

Looking at 12 Zones in the future and right now have just 4 completed; but going really slow.

 

[pete_c]

I received my 75 watt 12VDC DIN power supply yesterday (one pictured above on the right). I am going to switch initially one LED zone over to it. It currently has the following LED lighting on it.

Zone-1

1 - 4 .5 watt ( single LED/single circuit lamps (used to be 10 watts X 4 = 40 watts)
2 - 2 1 watt cree style small spots (used to be 35 watts X 2 = 70 watts)
3 - 1 12 LED 1 watt lamps (use to be 7 watts)
4 - 2 3 watt 12 LED lamps (used to be 35 watts X 2 = 70 watts)

If this works may put a second zone on it with a similiar number of LED lamps on it. I only have these two zones on one Toroidal transformer (way overkill as the transformer is 1000 watts); such that I can shut the legacy transformer off. (These two zones had a mixture of 10 watt, 20 watt and 35 watt halogen lamps on it). I can most likely put the DIN rail where the 1st transformer was once it is removed.