12.00 Volts to 10.00 Volts LED Bucker

[MEXICOWANDERER]

Never a dull moment. Genuine 10 watt LED chips (they need a heatsink) are not 12.00 volts capable.

Driven much higher than 10.00 volts, light output stays the same but heat increases as dramatically as lifespan decreases dramatically.

A realistic 2 volt drop (higher when batteries are being charged) is available by using series diodes.

A quandary. Christmas tree light string diodes or a DC to DC buck converter which is also a regulator.

But how nicely do DC to DC converters play at a 2.0 volt Delta T ??

Chinese manufacturers seem to be rather unclear on the subject.

"Work fine 12 volts 24 volts" But when I redirect specifically to the 12.00 volts to 10.00 volts question, it's either "So sorry don't know" or no response.

This question is not academic. "Properly" driven an LED can emit 95% of the light of a max driven chip but develop 80% of the heat. Heat means heat sink, and large heat sinks double or treble the price of a chip assembly.

Heat sinks are priced like diamonds. Go a little larger and WooWee.

Thanks for the input


EDIT

By the way, the light temperature of the 5K 10 watt chips is as close to sunlight as I have ever seen in an LED emitter. No pink or blue or yellow.

[Gdetrailer]

MEXICOWANDERER wrote:
I really don't think these chip manufacturers have their act together as far as knowing what their chips consume. They are after the "12 volt market" with a design that demands 10 volts. At 10 volts, I personally cannot discern much if any lessening of brightness, but amperage (watts) above 10 volts skyrockets.

I tried a competitor, Bridgelux, at six dollars a pop and at 600% of the cost of the run of the mill chip I was sorely disappointed to see very little if any perceptible lumen difference at the same I. Increasing I resulted in heat not more lumens just like with the cheap spread.

As compared to a 5050smd plate the single 10 watt chip just blows the plate away as far as brightness and whiteness is concerned. Very much like comparing the difference between a 7 watt incandescent night light, versus a 10 watt compact spiral. I'm talking about differentials, perspective not actual light output.

What is needed in the RV industry is an authentic LED lamp. Not a conversion. Base made of black anodized aluminum, finned, special diffuser plastic lens to minimize loss of lumens and spread the area of lighting.

Rural families use their car battery and 50 watt 12-volt light bulb. They go to bed with the chickens. If heat is tolerable they may fire off a Flameneta gas lantern to cook by. Expensive to operate, a humidity producer and shoveling more coal onto sweltering temperatures. A ten watt fixture will buy them some extra hours. One sixth the amp hour consumption of an incandescent bulb never mind savings in AWG reduction needed.

Pilas, small batteries down here can cost two dollars each. Ouch! The bread winner uses the car the battery will recharge. It's an absolutely imperfect, carnival of compromises but I've yet to come up with a more cost effective solution. A neighbor just purchased an LTH ciclo profundo bateria for his lancha and it cost eqvt 148 dollars. Please don't ask about solar voltaic. A panel that costs 100 dollars in the states costs 300+ dollars down here. Oh yeah, forgot about the 70 dollar shipping charge.

The chips you bought are RAW LED chips.

They are a simple 3 x 3 "array" of White LEDs.

Basically put 3 white LED diodes in series (as you know White LEDs typically need about 3V forward voltage across them so three in series is 9V) to make one set and three sets in parallel. The modules are actually 9W...

I have several of these I have been experimenting with, while the manufacturer "claims" they are 12V I decided to use four 1A diodes in series which dropped the voltage from 12.8 to about 10V. The diodes are dropping about .7V each.

ACTUAL Current draw is about .56A or 7.2W so the diodes in series are actually dissipating a "whopping" .39W of heat or a grand total of 1.575W of heat for all four diodes.

I would HIGHLY DOUBT that ANY DC-DC switching supply or converter is going to drastically be LESS wasted power than those four diodes.

Not to mention you can often buy 100 or more 1A diodes for a buck or so.. basically costs mere pennies per diode..

Granted, you do not get any over voltage protection nor current limiting but hey.. you just can not beat the simplicity and cost of the diodes..

[stevenal]

If you roll your own switching converter, you can dial it in to your application. I used the software from http://www.ti.com/ww/en/simple_switcher/index.html to make my low loss fan control.

[MEXICOWANDERER]

900 lumens, car battery powered, ceiling mounted, durable. The Coleman in the link would be fine for use atop a picnic table. The fixtures I am creating are a world apart in quality and function. Usable light for a 12X12 foot room or area. On a car battery not an RV battery. 30 foot long leads. Speaker duplex wire. They can add modules room by room. They all learned bitter lessons with abusing a battery with a 4.0+ ampere 50 watt 12 light bulb. I am not worried about them forgetting to hit the switch when they don't need light. Most use candles when navigating to and from the switch.

[Bend]

MEXICOWANDERER wrote:

...

What is needed in the RV industry is an authentic LED lamp. Not a conversion. Base made of black anodized aluminum, finned, special diffuser plastic lens to minimize loss of lumens and spread the area of lighting.
...

So, basically, you are trying to near duplicate this:

http://www.amazon.com/Coleman-Family-Size-LED-Lantern/dp/B00168QAGS/ref=sr_1_5?ie=UTF8&qid=1407791701&sr=8-5&keywords=coleman+LED+lantern

I've seen several single bulb LED lanterns/lamps that use an upside down clear plastic shot (whisky) glass as the diffuser.

[hawkeye-08]

Keep us posted on how this plays out.. it sure seems like a worthwhile pursuit. If you want to PM some details, just a quick schematic of what you are doing, I can ask my daughter, the electrical engineer, what she thinks.. never know, she might know of something to solve this problem.

[MEXICOWANDERER]

Thanks stevenal, Your push is exactly what I needed to make up my mind to search for affordable 1,3, and 10 amp rated buckers. They key word is affordable. My effort generates next to nothing profit wise. It's to help poor folks living beyond the power lines. With phone calls, etc even a pittance of profit vanishes.

I am financially challenged (politicallycorrectspeakthing) but it is so easy to find honest, gracious folks down here who have whole magnitudes less but yet never hear a gripe from them.

[stevenal]

We like LEDs because they save energy, but any device you add will reduce the overall efficiency. The added diodes will dissipate (waste) power by the product of the current through them by the voltage dropped across them. Drop two volts with diodes to 10V at 10 W, and I calculate 2 W dissipated by those diodes. Switching converters get around this little detail by switching quickly from off (little current) to on (little voltage drop). Still some loss of course, but I expect a good quality switching converter would provide the best efficiency.

[MEXICOWANDERER]

I really don't think these chip manufacturers have their act together as far as knowing what their chips consume. They are after the "12 volt market" with a design that demands 10 volts. At 10 volts, I personally cannot discern much if any lessening of brightness, but amperage (watts) above 10 volts skyrockets.

I tried a competitor, Bridgelux, at six dollars a pop and at 600% of the cost of the run of the mill chip I was sorely disappointed to see very little if any perceptible lumen difference at the same I. Increasing I resulted in heat not more lumens just like with the cheap spread.

As compared to a 5050smd plate the single 10 watt chip just blows the plate away as far as brightness and whiteness is concerned. Very much like comparing the difference between a 7 watt incandescent night light, versus a 10 watt compact spiral. I'm talking about differentials, perspective not actual light output.

What is needed in the RV industry is an authentic LED lamp. Not a conversion. Base made of black anodized aluminum, finned, special diffuser plastic lens to minimize loss of lumens and spread the area of lighting.

Rural families use their car battery and 50 watt 12-volt light bulb. They go to bed with the chickens. If heat is tolerable they may fire off a Flameneta gas lantern to cook by. Expensive to operate, a humidity producer and shoveling more coal onto sweltering temperatures. A ten watt fixture will buy them some extra hours. One sixth the amp hour consumption of an incandescent bulb never mind savings in AWG reduction needed.

Pilas, small batteries down here can cost two dollars each. Ouch! The bread winner uses the car the battery will recharge. It's an absolutely imperfect, carnival of compromises but I've yet to come up with a more cost effective solution. A neighbor just purchased an LTH ciclo profundo bateria for his lancha and it cost eqvt 148 dollars. Please don't ask about solar voltaic. A panel that costs 100 dollars in the states costs 300+ dollars down here. Oh yeah, forgot about the 70 dollar shipping charge.

[GordonThree]

90 lumens per watt is pretty poor, but I guess it's all about balancing efficiency with cost.

you mention running off non cyclic batteries, so are we talking one time use primary cells or just like a car starting battery? if it's one-time use, the SEPIC topology is really your friend, since it will suck that battery dry, assuming the current holds up.

might want to look into a flyback topology as well; google the joule thief... some people are doing crazy stuff with scaled up versions, like running compact-fluorescent bulbs from AA batteries.

[MEXICOWANDERER]

In parallel. Hope to run as many as four. Forty watts.

Frankly I do not trust operational specifications of Chinese manufacturers. They may post what looks to be succinct values, then I find them to be at variance with reality. A variable power supply and IR thermocouple tell no lies. When heat increases, the limit has been reached.

Thank you for the link. I read it. I bookmarked it.

I purchased a hundred 100mm 24 fin count heat sinks on eBay for a buck each. Drilled and tapped for the 10 watt devices. Including M3 screws and heat sink compound.

Trying to make lamps for rural homes. Extremely affordable. Some folks run wires, pop the hood and do the best they can for the night. One light on and off, kitchen & bedroom. They cannot afford cyclable batteries, and a six hour discharge at 10 watts is not going to break the bank. No I am not factoring in converter efficiency loss, here.

[landyacht318]

HOw many LEDs are you running in series?

I've been using this one for a month continuously and it can hold, at a fan rated at 1.3 amps, 1.2 volts below input voltage, and the output voltage stays steady no matter load or input voltage.

http://www.amazon.com/DROK-Adjustable-Regulator-Experimental-Converter/dp/B00BYTEHQO/ref=sr_1_1?ie=UTF8&qid=1407222286&sr=8-1&keywords=DC-DC+Voltage+Regulator

They have less expensive versions without the voltmeter display.

[MEXICOWANDERER]

Here are the chip OEM specs. I am attempting to keep finished price under control. I am dealing with multiple dozens of chips and heatsinks. Some are individual lights, others are small clusters to (4) units.

Color: Cold white
Forward Voltage (VF): DC 9-12V
Forward current (IF): 1050MA
Out put Lumens: 800-900LM
Color temperature: 6000-6500K
Beam Angel: 140 degrees
Life span: >50,000 hours
Size:
Lens Color:Water clear
Viewing Angle:120°

[MrWizard]

Mexi
did you see this thread

DC buck converter

4.5vdc~23vdc input

output 0vdc~20vdc

2amps 40w max

panel mount, with digital display

[GordonThree]

If your LED (array) is bare, that is, no other electronics involved, then you can put voltage aside and only worry about current, since LEDs are current mode devices.

On china-e-bay, there are plenty of adjustable constant-current LED drivers. If your delta-v is very small, a SEPIC type driver might be the best fit, as it allows input voltage to be higher or lower than output voltage.

350mA SEPIC driver

700mA SEPIC driver