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Forum Index : Electronics : Cheap 12v LED’s
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Bunnings hardware have been selling these 4 packs of 12volt 3watt down light LED's cheap for a few weeks now. $10 per pack, so I bought 5 packs. They also have 240v LED downlights ( different connector ) for the same price, so grabbed a couple of those too. 
I had to rewire my house recently with new 3 core wire, and saved the old 2 core wire. I've been soldering the 12v LED's to this 2 core wire and sealing the joint with some hot glue. The old 2 core wire is easy to bend and will retain that shape, within reason. 
And these are some of the ways I've used the LED's. A handy light for clipping on a 12v battery. 
A 12V lamp, I have a few 12v outlets around the house. 
A work light above a work bench. Same deal, I have 12v outlets all over the place. 
The 3 watts of light is more than I expected, and it only draws 300mA per LED. Next up I'll be adding a couple to the ride on lawn mower. Its surprising just how little power you need to light a house, if the lights are well placed. My kitchen has a 4watt LED light above the sink, where I prepare my food, and the light from this single LED also shines into the lounge room. So at night when I'm cooking dinner, or relaxing watching TV, I'm running a single 4 watt light! Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| dwyer Guru  Joined: 19/09/2005 Location: AustraliaPosts: 574 |
Hi Gizmo I saw this at Bunnings hardware about 10 days ago and never thought of buying 4 packs of 12volt 3watt down light LED as however some months ago i bought three 6 watts LED outdoor flood light 240 volts and only last fews months as i pulled it apart as two of LED was blow. I will never buy it again as there are two many LED so when one blows all blows  . Will post some picture soon
Ian |
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Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9308 |
That is brilliant work. 
I am guessing that the old wire is 1mm twin for lighting circuits, and is solid-core? Never thought of using old wire like that, and I have a box full of off-cuts... Smoke makes things work. When the smoke gets out, it stops! |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Hi Ian Will see how long they last. I've been using them for a few months now, so far so good, and they dont get hot so should last longer. Yep Grogster, its old light circuit wire, solid core. Nice to work with. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
I assume there is a tiny rectifier and some components for some basic current limiting inside the MR16/GU5.3 LED body, similar to what is visible on the LED strips? I'm confused, no wait... maybe I'm not... |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Hi Yahoo Just pulled one apart to have a look. I was expecting to see a few LED's and a series resistor, but found 6 surface mount LED's on a aluminium heat sink, and a circuit board containing a full wave bridge, IC, couple of inductors, 330uF 25v cap and a dozen other components. Construction is good. So good, that I'm going to buy a few more 
Will take some photos later and post. These were found in a bargain bin at the Bunnings store, boxes and boxes of them. Its superseded stock. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Pics as promised. To open them up, I prised off the front diffuser cover and undid a couple of screws, easy. 
The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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powerednut Senior Member  Joined: 09/12/2009 Location: AustraliaPosts: 221 |
i wonder if that 8 pin chip is a dedicated LED driver or if its just a bog standard switched mode power supply chip. |
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Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
Really who cares at the price they are sold at. To me it looks to be a well laid out tidy circuit board, and for that reason i would think Glenn has discovered a gem of a item. Then only time will tell, but for the cost its well worth the experiment to test them out, as its a little cost to gain a low energy result. Pete. Sometimes it just works |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
ooOOH! that looks impressive. I hope they are on sale in regional SA, they would be just the ticket for a workbench lightbar. I'm confused, no wait... maybe I'm not... |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Powernut its a BP1601. Looks like a dedicated LED driver IC, I found this.... "BP1601 is a step-up DC/DC converter designed to drive high brightness LED from 4.5V to 24VDCinput voltage . Typically in 12VDC input voltage, up to seven 1W LED strings is able to be drived. BP1601 works in current mode to control LED current, it set the LED current by sense resistor, this low-side sensing strategy is used to minimize the power dissipation and improve system efficiency. BP1601 detects the OV pin voltage to provide open circuit protection. The BP1601 includes under-voltage lockout, current limiting and thermal overload protection preventing damage in the event of an output overload. BP1601 is assembled in SOP-8PP package, which provides excellent heat dissipation and thermal" (ref) Interesting bit of gear. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| M Del Senior Member Joined: 09/04/2012 Location: AustraliaPosts: 155 |
Damn, my local has them at $15 a pack  , so I bought the last 2 packs I could find .
wonder why the price difference for an item being superseded/bargain binned? They do however have some with a gu15(?) base 240v, the rest of the light is the same. Time for a trip to visit some family about an 1.5 hours away. There is three stores between me and them. They will be perfect for lighting up the garden sheds. Mark |
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rustyrod Senior Member Joined: 08/11/2014 Location: AustraliaPosts: 121 |
Anyone prepared to connect one to 24 volts ? If the BP1601 is rated at 24 volts will it take 28.8v ? Maybe wire some resistor in the supply lead ? Always Thinking |
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| M Del Senior Member Joined: 09/04/2012 Location: AustraliaPosts: 155 |
Instead of some resistor wire would it be possible to wire them in series? I have used standard 12v car bulbs in series in 24v set ups before, but not the LED ones. Most of the vehicle LED bulbs are rated 12/24(some rate up to 36v), so are a straight fit into any vehicle or trailer. They cost more than $3 as well. More study required in electronics by this little black duck. Mark |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Tested one at a few different voltages. They work down to 6 volts with no change in intensity, but under 5.5v they dim and drop out. Over 18 volts the intensity drops off, and the current goes up, which cant be good! Some readings 6v, 630mA, 3.78watts
12v, 260mA, 3.12watts 
24v, 440mA, 10.6watts 
So at 24v I expect they would quickly cook and die. Two in series would work well, but can complicate the wiring. A series resistor could be used, but it would need to dissipate 3 watts, which is a waste and means the whole circuit would use 6 watts to light a 3 watt LED. The resistor can be calculated using R=V/A and W=V*A, so if we want to use a 24v supply, we need to dump 12v across the resistor, at .26A, since thats what the LED will draw . So R=12/.26, or 46.1ohms. W=12*.26, or 3.12 watts. A 47ohm, 5watt resistor would do it. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| M Del Senior Member Joined: 09/04/2012 Location: AustraliaPosts: 155 |
The Bunnings web site has these lights priced at the $15 I paid for mine. There is supposedly a lot of stock available, and according to the team member I spoke to on the phone today they are a fairly new stocked item and have sold well for the period they have had them locally. More will arrive tomorrow was the word, I will drive over and see if there is any more. So if the guy on the phone knows what he is talking about I will pick some more up tomorrow, and then will know what the truth is. Old superseded bargain bin stock being run out and none to be had, or newish and still available. Seems odd they would be new in my area and superseded in glens area. Mark |
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| rustyrod Senior Member Joined: 08/11/2014 Location: AustraliaPosts: 121 |
At Toowoomba $5 per 4 today. About 1 and 1/2 box left. Always Thinking |
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| rustyrod Senior Member Joined: 08/11/2014 Location: AustraliaPosts: 121 |
In series - not going to work - one bright- number 2 flickering madly Reverse connections - one flickering - number two bright No difference with which one is connected what way/which way Tried some more - same difference. OR put your finger across the flickering one's terminals and PRESTO it becomes bright and the other one flickers. Spit on the finger - faster result! I WILL BUY SOME RESISTORS. Always Thinking |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Try a 10k resistor across each LED, see if that works. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Or, a couple of 15v zeners? One across each LED, cathode to the +ve supply. The two zeners in series wont affect the supply unless it goes over 30v, so be sure this cant happen or the zeners will cook. The zener will clip each LED to 15v max, to the other LED will get 9v, if its a 24v supply. Results may vary, would need to experiment. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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