warm-white 12v LEDs ?

[RustyShackleford]

Has anyone been able to locate any 12v LED bulbs that are REALLY "warm white" - that is, they have a color temperature of 2700 degrees (or less) and a good CRI (color rendering index) ?

I am doing some landscape lighting, and I don't want to have the electricity consumption (or the wiring requirements) of incandescent bulbs. But so far I can't find any that don't look like dog puke (even ones that claim to be "warm white").

I'm specifically interested in "wedge base" bulbs, and in rope light.

I've looked at 1000bulbs.com and at superbrightleds.com. I've bought some ZoneTech ones of Amazon that look like crap (FWIW, they did not claim any particular color temp).

 

[begreen]

I put warm white LED bulbs in our camper van. They look great. I think they were "Ming" brand bulbs. Mine are bayonet based. I got both 250 lumen and 125 or 150 lumen bulbs depending on the fixture.

Here are some possibles in the 3000K range -
http://www.rvledbulbs.com/product-p/hp-0921w.htm
http://tweetys.com/ming-s-mark-led-bulbs.aspx
(broken link removed to http://www.dyersonline.com/ming-s-921-t15-green-long-life-100-lumens-led-bulb.html)

 

[RustyShackleford]

Thanks for the links. The Ming "warm white" seem to be 3000-3500 Kelvin. I was hoping for 2700 or less, but maybe I ask for too much. My main dissatisfaction with the el-cheapo ones (ZoneTech, $1 each) I got from Amazon is that there's a greenish tint. Hopefully this is a case where you get what you pay for, and if I spring for $6 or more per bulb, I'll get something acceptable.

 

[begreen]

They are not the same warmth as the original incandescent bulbs, but not bad at all. We have some 5000K lights too and they appear ghostly in comparison. The bulbs I linked to are high lumen. You many not need that brightness depending on the application.

 

[jrems]

Ikea might have some. The regular based bulbs I have got from them are the warmest I have found. They are rated at 2900k but compared to Cree or phillips 2900k they are noticeably warmer and more yellow.

 

[RustyShackleford]

Ikea might have some. The regular based bulbs I have got from them are the warmest I have found. They are rated at 2900k but compared to Cree or phillips 2900k they are noticeably warmer and more yellow.

Yeah, I have some 120v LED bulbs from IKEA and like them. Have you seen 12v ones there ?

 

[begreen]

Here's a lighting comparison of 5000k LED interior lamps (in front and on right) and the 3000k LED Ming bulbs (on the left).

 

[jrems]

I don't know if the ikea ones are 12v they do have some small bayonette base ones that replace thier old halogen bulbs in some of their small lamps. There is a led subforum on hidplanet.com. There are a lot of guys who make thier own custom 12v led assemblies using raw Cree and other leds for automotive use.

 

[RustyShackleford]

Here's a lighting comparison of 5000k LED interior lamps (in front and on right) and the 3000k LED Ming bulbs (on the left).

Thanks. Hard to tell too much from the picture, but it sure seems like the 3000 ones don't have th yucky greenish tint I've seen on so many cheap-o LED bulbs.

 

[RustyShackleford]

I don't know if the ikea ones are 12v they do have some small bayonette base ones that replace thier old halogen bulbs in some of their small lamps. There is a led subforum on hidplanet.com. There are a lot of guys who make thier own custom 12v led assemblies using raw Cree and other leds for automotive use.

Yeah, Cree seems to make the best LED bulbs - their 120vac ones are great - but I don't think they do 12v ones. But like you said, maybe I could buy some of their LEDs and wire 'em up.

 

[purduephotog]

I can't answer this at this moment but I'll try (hi I'm new).

There has been tons of LEDs at what you've asked... But what you want is a full bulb and that's harder to get.

Cree and nichia both have 90+ cri LEDs in warm white with beautiful spectrums.

You'll pay however.

12 v isn't that special either a standard mr16 buck puck will convert for you.

Let me look at work tomorrow and see if anything sticks out.

 

[RustyShackleford]

Let me look at work tomorrow and see if anything sticks out.

Thanks ! Do you have a pointer on the good Cree LEDs and where to buy 'em ? I actually live in Cree-land. And I'm an electrical/computer engineer. So maybe something will work out !

And welcome to hearth-dot-com. It's a great place.

What do you mean by an "MR16 buck puck" ?

 

[purduephotog]

Thanks ! Do you have a pointer on the good Cree LEDs and where to buy 'em ? I actually live in Cree-land. And I'm an electrical/computer engineer. So maybe something will work out !

And welcome to hearth-dot-com. It's a great place.

What do you mean by an "MR16 buck puck" ?

Cree makes dies. The sell some that then get soldered onto stars. The stars are what you see in flash lights, etc.

A buck puck cuts voltage down to an led. Most of the examples you mentioned use a resister to limit the current while a buck converter is A DC to DC converter. It can regulate current (which is what an LED uses) while letting the voltage float. (Simplified).

So if you can find good fixtures with junk LEDs in them you can pretty easily swap out the star with a good one. As bigger companies enter the chain it gets a little harder though as their products sometimes get very specialized.

Check out DX.com and see if there is anything there. You can always get into building your own too...

 

[RustyShackleford]

Thanks for the explanation. I know nothing about LED lights and would like to know more - can you recommend a good link ? Wow, a DC-to-DC converter ? I was figuring there's a big inefficiency with resistors, since if the forward diode drop is near the 1.5v or so typical of silicon, that'd mean most of the 12volts is dropped in the resistor (to the extent you don't have multiple diodes in series). But I'd presume a bulb with a DC-to-DC converter could not work off the typical 12vac landscape transformer - though it'd be fairly easy to add a bridge rectifier to the transformer.

I can't believe no one makes a 12v LED bulb with great light quality - not in a wedge-base, at least - but it seems to be true. So if I have to make my own, I think I will.

 

[sportbikerider78]

You're looking in all the right places. There are many good options out there for warm LEDs.

 

[RustyShackleford]

You're looking in all the right places. There are many good options out there for warm LEDs.

Well, there are some good options for the MR16 bulbs that go into the bigger landscape lights, like ones that point up at trees and so on.

But for the little wedge-base bulbs, which go in the smaller fixtures like the ones lining my driveway, there don't seem to be any good options. I'm not sure why, except maybe they're so small that not much electronics can be put in there.

But Cree makes some wonderful bare LEDs - 2700 degrees or lower with CRI as high as 90. I'm trying to figure out how to DIY my own wedge-base bulbs from them. What I can't figure out, is why can't I just take THESE LEDs:

(broken link removed to http://www.cree.com/LED-Components-and-Modules/Products/XLamp/Discrete-Directional/XLamp-XTE-HVW)

and connect them directly to 12vac ? I understand that the normal practice is to use an LED "driver" to provide a constant current to the LED itself. But if you click on "Download Data Sheet" in the above link, and look at the graphs (for the 12v version) on pages 6 and 7, you'll see curves giving Forward Current as a function of Forward Voltage, and Relative Luminous Flux as a function of Forward Current. So a given forward voltage will give me a certain number of lumens. Yes, maybe there's more variation, as opposed to if I supply a given forward current (with an LED driver), but maybe not, as the variabilities are as likely to cancel out as to add; but I don't really care, as long as the bulbs in a given set (say, a string of light along the driveway) have similar brightness. Meanwhile, they can withstand forward voltages as high as 13.5v, so I';m safe there.

There's the issue of whether giving them 12vac, as opposed to 12vdc, is ok. For some odd reason, they don't spec maximum allowable reverse voltage, but I'd be shocked if it's not a lot higher than 12v. That being said, I'm so desperate that I'd actually consider adding circuitry between my 12vac transformer and the LEDs (not EACH LED, too big) but too a string of them. Say, a bridge rectifier. Or maybe even a DC-to-DC converter to step down the voltage.