Author Topic: 12v ac/dc led clusters  (Read 5422 times)

0 Members and 1 Guest are viewing this topic.

dnix71

  • SuperHero Member
  • ******
  • Posts: 2268
12v ac/dc led clusters
« on: September 12, 2011, 06:22:46 PM »
http://www.ebay.com/itm/G4-18-LED-180-Lumen-Cool-White-12V-AC-DC-2-Watt-Bulb-/150647480705?pt=LH_DefaultDomain_0&hash=item23134a2181

I just bought one to tinker with. That's enough light at 2 watts to light a small room. I don't want to dim this but would consider running it from 9vdc since I have a 9v regulated tap available.

Can it be run from 12-14v dc directly or do I need a small resistor to limit current? I can heat sink this well if need be, but the 2 watt led 120vac bathroom lights I have don't seem to need a sink, unless the socket itself acts as one.

90 lumens/watt is a good efficiency for almost any type of lamp. Even linear fluorescents don't do much better.

Simen

  • Sr. Member
  • ****
  • Posts: 434
  • Country: no
  • Grimstad, Norway
Re: 12v ac/dc led clusters
« Reply #1 on: September 13, 2011, 12:33:51 AM »
I have several similar lights, and it all depends if they have a current limiting circuit or not wether you can run it much above 13-14V.

The ones i have that have just a resistor in series with each 3 leds, works fine at 12-13V. @14V they're very warm, and when my bank are fully charged in wintertime when the voltage reach 15V; the leds started to melt off... ;D

Edit:
If the light are the 3-led/1-resistor type, it will probably not light up @ 9V...
/edit

I have swapped all those with similar lights that have a current limiter circuit, and those run from 9V to 30V.
« Last Edit: September 13, 2011, 12:41:19 AM by Simen »
I will accept the rules that you feel necessary to your freedom. I am free, no matter what rules surround me. If I find them tolerable, I tolerate them; if I find them too obnoxious, I break them. I am free because I know that I alone am morally responsible for everything I do. - (R. A. Heinlein)

dnix71

  • SuperHero Member
  • ******
  • Posts: 2268
Re: 12v ac/dc led clusters
« Reply #2 on: September 16, 2011, 07:31:07 PM »
It came in today. I live in a 14' x 15' apartment. It's enough to light the room at night. I measured the current at 12.8v and it's steady at .142 amp. That's not quite 2 watts, so I assume it can handle a "nominal 12v" rather than exactly 12v.


for size comparison


for size comparison


Shot at night with the flash down

oldmil

  • Newbie
  • *
  • Posts: 15
Re: 12v ac/dc led clusters
« Reply #3 on: November 03, 2015, 06:35:00 PM »
I just bought a few of these lights.  Is there a + and - terminal on these or doesn't polarity matter.

Thanks,

Oldmil

dnix71

  • SuperHero Member
  • ******
  • Posts: 2268
Re: 12v ac/dc led clusters
« Reply #4 on: November 03, 2015, 07:21:47 PM »
Four years later, my apartment is still lighted by that cluster and none have burned out. I don't see a polarity label on it, but diodes are by nature polarized.


oldmil

  • Newbie
  • *
  • Posts: 15
Re: 12v ac/dc led clusters
« Reply #5 on: November 03, 2015, 07:25:47 PM »
So it doesn't matter which lead gets hooked to + or -?  I know the other led's I've messed with had a + and - and would blow out if hooked up incorrectly.

Sorry for my questions but I'm by no means well versed in LED's.

Thanks again.

Oldmil.

dnix71

  • SuperHero Member
  • ******
  • Posts: 2268
Re: 12v ac/dc led clusters
« Reply #6 on: November 03, 2015, 07:47:50 PM »
I went back to the original list on eBay and the listing does say 12 v ac or dc, so it doesn't matter.

http://www.ebay.com/itm/G4-18-LED-180-Lumen-Cool-White-12V-AC-DC-2-Watt-Bulb-/150647480705?pt=LH_DefaultDomain_0&hash=item23134a2181

It has a symmetric unlabelled bi-pin plug.

http://www.ebay.com/itm/G4-18-LED-Tower-250-Lumen-Cool-White-12V-AC-DC-3-Watt-Boat-Marine-RV-Landscape/151046612021

is a link to a currently available equivalent. It is also labelled ac or dc 12v.

oldmil

  • Newbie
  • *
  • Posts: 15
Re: 12v ac/dc led clusters
« Reply #7 on: November 03, 2015, 07:58:41 PM »
Thanks much for the info.

Hopefully these will serve me as well as they have you.

Oldmil.

tanner0441

  • Hero Member
  • *****
  • Posts: 985
  • Country: wales
Re: 12v ac/dc led clusters
« Reply #8 on: November 04, 2015, 03:46:50 PM »
Hi

We used to fit LED panel lights on the computer room AC units the firm I worked for made. They had a cluster of LEDs wired alternate way round, and run them off ac. Diodes are a rectifier and as long as the voltage is not over the breakdown voltage they block the reversed current.

Brian

Mary B

  • Hero Member
  • *****
  • Posts: 796
Re: 12v ac/dc led clusters
« Reply #9 on: November 04, 2015, 04:50:30 PM »
LED Light Emitting DIODE so they will not croak if reverse voltage is applied unless you exceed its PIV rating.

DamonHD

  • Global Moderator
  • SuperHero Member
  • *****
  • Posts: 3651
  • Country: gb
    • Earth Notes
Re: 12v ac/dc led clusters
« Reply #10 on: November 05, 2015, 05:28:28 AM »
Some care has to be taken if running long strings of them that any reverse voltage is balanced out.  Probably leakage current would take care of it, but it's worth considering.

Rgds

Damon

OperaHouse

  • Hero Member
  • *****
  • Posts: 1078
  • Country: us
Re: 12v ac/dc led clusters
« Reply #11 on: November 05, 2015, 07:19:27 AM »
I have about a dozen of those clusters in my lighting.  Even with rather low use and minimal voltage, four of them have begun to twinkle on and off.  I find that an amazing failure rate.

Mary B

  • Hero Member
  • *****
  • Posts: 796
Re: 12v ac/dc led clusters
« Reply #12 on: November 05, 2015, 08:41:59 PM »
I see no current limiting in them... I would measure the current then make a constant current supply that is about 3/4 of measured. That would extend the life greatly!