LED's for landscape (cont)

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RickH - 07 Jul 2008 17:07 GMT

Has anyone ever put a watt meter on the primary side of a typical
Malibu lighting transformer to determine how much power is saved by
simply changing the bulbs on the string to LED's? Just curious if
anyone has some real number comparisons.

I wouldn't think the cost savings would be that great considering the
transformer losses and price of LED bulbs. And wouldn't Malibu
already have drop-in LED bulbs to retrofit their legacy products if
there really were great payoff?

Also how do LED bulbs hold up to 6 months of winter?

(sorry my post was failing to the original thread so started a new
thread)

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BruceR - 07 Jul 2008 19:03 GMT

If you directly replace the bulbs with plain LEDs they won't work. LEDs
operate at 3-5 volts DC and the transformer for your Malibu lights is
most likely 12volts AC. So you'd need to ad a rectifier to convert AC to
Dc (or just get the proper transformer). Further, you'll find that the
light from a single LED doesn't hold a candle (pun intended) to the
brightness of the incandescent bulb. Lastly, the Malibu transformers
don't use that much energy in the first place. I'd be surprised if it
cost more than a buck or two a month to run them.

> Has anyone ever put a watt meter on the primary side of a typical
> Malibu lighting transformer to determine how much power is saved by
[quoted text clipped - 10 lines]
> (sorry my post was failing to the original thread so started a new
> thread)

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Jeff Volp - 07 Jul 2008 19:34 GMT

The MR16 LED replacements that I reviewed in the other thread are designed
for 12VAC operation. The two samples appear to have a regulator because the
current does not continue to increase once 12V is reached. I bench tested
them to verify their power consumption was as stated. You may also be
surprised how bright they really are. They appear to be about half as
bright as a 20W halogen MR16. The best one for my application had 9 surface
mount LEDs, and produced a very wide even pattern on 2.6W:

http://www.ledwholesalers.com/store/index.php?act=viewProd&productId=322

Considering the power savings, the brightness seems adequate. The real
issues are color temperature and whether their longevity will be sufficient
to provide the expected payback.

I agree that the transformer doesn't use much power. The 300W transformer
case is barely warm to the touch.

Jeff

> If you directly replace the bulbs with plain LEDs they won't work. LEDs
> operate at 3-5 volts DC and the transformer for your Malibu lights is most
[quoted text clipped - 19 lines]
>> (sorry my post was failing to the original thread so started a new
>> thread)

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Homeowner Forum / Home Automation / July 2008

LED's for landscape (cont)