Author Topic: My attempts on white LED [2]  (Read 3288 times)

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prasadbodas2000

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My attempts on white LED [2]
« on: September 09, 2012, 06:57:53 AM »
Hi All,

I tried to install simple and cost effective LED lighting, aim being to drive the lights of my home directly from a battery which is charged by solar panels and to avoid an inverter.

Here are some pictures of the units I built using the 3W white LEDs.

These available here in Mumbai, India are mostly unbranded and are from chinese sources, approximately priced at 50 INR (less than a USD) per piece. Noone specifies lumens delivered/ permisible current etc. These LEDs need a heat sink and are expected to be more stable than those w/o a heat sink (I have tried some of such non-heat-sink units in my post at http://www.fieldlines.com/index.php/topic,145701.msg992212.html#msg992212 )

I am sure these units as built and seen in below images are very much crude looking and do not have much asthetic get-up, but I am happy with the light they give and I want to test their stability and deterioration in the output over a few days/months.

Each unit has 6 such LEDs, with a LM317 connected in a voltage regulator mode to give 9.7 VDC for a string of 3 LEDs in series. Each LED is said to support an input voltage of 3.2 to 3.4 VDC.

The backing and holding strips made of aluminium C sections are seen to provide good heat sinking. I have seen the aluminium surface temparature to rise to 65 DegC max approximately in standstill room air. Well this is measured only by finger-touch-sensing :-)

A pair of 2 Such units in one room is failry equivalent to a 40 Watt fluroscent tubelight (the 4ft length standard lamp) in terms of light output.

With thanks and regards,
Prasad

dnix71

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Re: My attempts on white LED [2]
« Reply #1 on: September 09, 2012, 09:23:03 AM »
You should be able to drive those hard with big heat sinks like that. 12v leds are cheap to buy now. People have begun to make retrofit kits for cars to decrease alternator load (more power for their booming sound systems).

The dome light retrofits have a nice beam spread and are much brighter than the originals.

These are tail lights. You can't make them for this price. http://www.ebay.com/itm/1156-BA15S-SMD-18-5050-LED-White-Light-Bulb-Car-Brake-Stop-Turn-Tail-DC-12V-/130761903061?pt=US_Light_Bulbs&hash=item1e72044bd5

For $1 you get an assembled cabinet light. http://www.ebay.com/itm/G4-21-LED-Cabinet-Spotlight-Spot-Light-Bulbs-Lamp-12V-/251145588135?pt=US_Light_Bulbs&hash=item3a79718da7

prasadbodas2000

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Re: My attempts on white LED [2]
« Reply #2 on: September 09, 2012, 10:54:04 PM »
Hi Dnix,

The lamps in the links you provided are just too good, compact and seem to be easily available at reasonably low prices. Thanks for sharing.

I assume that they must be having current limiting mechanism built in them to take care of battery voltage fluctuations especially due to charging current from the car alt.

It is amazing to see the benefits of mass production :-)

XeonPony

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Re: My attempts on white LED [2]
« Reply #3 on: December 01, 2012, 10:14:49 AM »
nope most leds just float you'll see them pulse with the field regulater lol. OP very nice, all you'd have to do is buff the aluminium and clear coat it to give you a professional designer look!

Very impressive again mate!
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WindJuggler

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Re: My attempts on white LED [2]
« Reply #4 on: January 17, 2013, 09:15:15 AM »
Hello,

I did build some LED lights myself too. I used some simple aluminum plates and revetted the leds on there with some thermal paste (Leds on a star). To get a better lighting, I covered the LEDs with some clear plexiglass sanded on both sides. That gave me some great results.

To run them from a battery, I ordered some simple buck or boost driver boards that are able to clip the amperage.

Regards,

Wim
Wim