12v LED w/traditional screw in connect available?

notsobright · November 2010

I have a 12 volt, 15 watt cfl that has a screw in base and now I wonder if there is something like this (12v) in LED?

Im finding every kind of 12v LED imaginable except for on that uses a standard bulb socket.

anyone seen or know of such?

thanks

MisterB · November 2010

Re: 12v LED w/traditional screw in connect available?

Looking at the hundreds of LED bulbs on eBay, these are the few I've found.

http://cgi.ebay.com/12V-180-LED-Light-Bulb-Screw-12-Volt-Lamp-Boat-Ship-RV-/390173488512?pt=LH_DefaultDomain_2&hash=item5ad826f580

http://cgi.ebay.com/2x-E27-SCREW-WHITE-LED-Artwork-Lamp-Light-Bulb-12V-E1W-/120501645720?pt=LH_DefaultDomain_0&hash=item1c0e753198

Most of what's available are LED versions of 12v Halogen bulbs that use GU10 or MR16 sockets

notsobright · November 2010

Re: 12v LED w/traditional screw in connect available?

the first one looks like exactly what Im looking for.

but seller in Hong Kong and no warranty. mabey something will come up thats easily available in the US somewhere.

if not I might give it a try later.

thanks

RCinFLA · November 2010

Re: 12v LED w/traditional screw in connect available?

I think it is bad practice to use standard medium E26 Edison screw-in bases for 12 v lights. Just too easy to have someone make a mistake and screw it into a 120 vac light fixture. How a given 12v light may react is anybody's guess. Might explode in a child's hand or rain glass shards in someone's face.

Anyway, make sure the LED replacements use switching supply to power LED's. It is just too cheap and simple to put two or three LED's in series with a ballast resistor for 12v operation. This yields poor efficiency, generates more heat, and has a lot of drive current variation over battery voltage range.

notsobright · November 2010

Re: 12v LED w/traditional screw in connect available?

very good points RCinFLA.

the reason I have asked for the screw in type is because I would like a LED light that works like a traditional light bulb. lighting in all directions (or nearly) you know what I mean..

I would actually like to find one that does this without the screw socket for the reasons you mention and also from my experience they are prone to have bad contacts and attaching points and so using these with low voltage would be an increased fire hazzard.

but what else would work for a simple light in the top center of a room to light as many directions as possible?

I also didnt know that some have ballast resistors.. that would kinda defeat the purpose. at least for energy conservation anyway.

this might be another DIY project.. sadly, seems to be the only way to get it done right these days.

thanks for your input RC, it helps a lot!

MisterB · November 2010

Re: 12v LED w/traditional screw in connect available?

RCinFLA wrote: »

Anyway, make sure the LED replacements use switching supply to power LED's. It is just too cheap and simple to put two or three LED's in series with a ballast resistor for 12v operation. This yields poor efficiency, generates more heat, and has a lot of drive current variation over battery voltage range.

You can put up to 4 LEDs in series with a resistor at 12 volts and with 4 LEDS this is not ineffecient. The more LEDs you put in series with a resistor, the less resistance you need in the circuit and the more power goes to the LEDs and not the resistor. 4 20ma 5mm LEDs in series with a 10 ohm resistor at 12 volts makes for around 1/4 watt. 4 80ma 10mm LEDS in series with a 2.2 ohm resistor makes for around 1 watt. You can use higher power LEDs for more light or make a bulb with parallel low wattage branches. The drive current variation in a typical 12 volt system is going to be 12-15v/resistance. Not that huge a variation. A mini switching power supply--like in a 1 1.5v battery powered LED flashlight--is not necessary at 12 volts unless you want a lot of LEDS in the bulb and is another circuit that can fail and make the light go bad.

MisterB · November 2010

Re: 12v LED w/traditional screw in connect available?

notsobright wrote: »

I would actually like to find one that does this without the screw socket for the reasons you mention and also from my experience they are prone to have bad contacts and attaching points and so using these with low voltage would be an increased fire hazzard.

The GU10 and MR16 sockets are a good bet. They are very common 12 volt halogen lights and you can get all kinds of light fixtures that use them and a lot of halogen lights come with a 120ac to 12 volt transformer that you just bypass. The GU10 halogen bulb comes in both 120 and 12 volt versions so you can easily find GU10 fixtures without a transformer. There are a lot more 12 volt LED bulbs for these sockets than for the screw in types because they are much more common as 12 volt halogen lights.

RCinFLA · November 2010

Re: 12v LED w/traditional screw in connect available?

MisterB wrote: »

You can put up to 4 LEDs in series with a resistor at 12 volts and with 4 LEDS this is not ineffecient. The more LEDs you put in series with a resistor, the less resistance you need in the circuit and the more power goes to the LEDs and not the resistor. 4 20ma 5mm LEDs in series with a 10 ohm resistor at 12 volts makes for around 1/4 watt. 4 80ma 10mm LEDS in series with a 2.2 ohm resistor makes for around 1 watt. You can use higher power LEDs for more light or make a bulb with parallel low wattage branches. The drive current variation in a typical 12 volt system is going to be 12-15v/resistance. Not that huge a variation. A mini switching power supply--like in a 1 1.5v battery powered LED flashlight--is not necessary at 12 volts unless you want a lot of LEDS in the bulb and is another circuit that can fail and make the light go bad.

You cannot push the limit on LED stack being so close to battery voltage due to variation in battery voltage across the range of absorb charge to minimum battery discharge voltage. That is 12.3vdc to 14.5 vdc, not including possible equilizing to 15+ vdc.

12 vdc supply with 10 ohms and 20 mA is 0.2 vdc of ballast voltage, almost nothing. If you had 20 mA at 12vdc that is 2.95 vdc per LED. Take that up to 14.5 vdc and you would have like over 200 mA. Actually you would not as one of the LED's would have blown before the charger got to absorb level.

MisterB · November 2010

Re: 12v LED w/traditional screw in connect available?

RCinFLA wrote: »

You cannot push the limit on LED stack being so close to battery voltage due to variation in battery voltage across the range of absorb charge to minimum battery discharge voltage. That is 12.3vdc to 14.5 vdc, not including possible equilizing to 15+ vdc.

12 vdc supply with 10 ohms and 20 mA is 0.2 vdc of ballast voltage, almost nothing. If you had 20 mA at 12vdc that is 2.95 vdc per LED. Take that up to 14.5 vdc and you would have like over 200 mA. Actually you would not as one of the LED's would have blown before the charger got to absorb level.

I'm using 3 lights with that design right now. I made them around 3 or 4 years ago. They are so near the limit for a 12 volt circuit that they go out if the voltage drops below 11 volts. I've left them on in the daytime and they have seen as high as 16 volts. As you add LEDs in a series circuit, each LEDs junction voltage will decrease the voltage seen at the resistor. The sum of the junction voltages will remain constant and the voltage seen across the resistor will be the supply voltage minus the sum of the LED junction voltages. This works for ordinary diodes as well. I've worked this out experimentally and somewhere I have a notebook with different resistance values for different LED circuits. The main problem I've had with LED lights is finding good quality LEDs. I've found a couple of good sources in Hong Kong. A lot of manufactured LED lights are made with poor quality LEDs and will fail in no time at all.

BB. · November 2010

Re: 12v LED w/traditional screw in connect available?

LEDs should really be driven with a current mode source / regulator / ballast...

The junction voltage of an LED is very voltage sensitive (small swings in voltage cause large swings in current) and it is also temperature sensitive (increasing temperature causes the junction voltage to fall, which allows more current flow--You can get thermal run-a-way with improper ballast resistors/circuits).

If you want to build your one ballasts/LED setups... The Candle Power Forums has way too much information on LEDs and electronic ballasts

:

www.candlepowerforums.com/vb/

-Bill

MisterB · November 2010

Re: 12v LED w/traditional screw in connect available?

Re Diodes of which LEDs are a special class of:

http://www.kpsec.freeuk.com/components/diode.htm

Here is the section about LEDs with how to calculate resistance values:

http://www.kpsec.freeuk.com/components/led.htm

The most relevant to this subject is:

Forward Voltage Drop
Electricity uses up a little energy pushing its way through the diode, rather like a person pushing through a door with a spring. This means that there is a small voltage across a conducting diode, it is called the forward voltage drop and is about 0.7V for all normal diodes which are made from silicon. The forward voltage drop of a diode is almost constant whatever the current passing through the diode so they have a very steep characteristic (current-voltage graph).

The forward junction voltage for LEDs is higher than for rectifier diodes which limits the number you can put in a series circuit at a given voltage. At 12 volts this comes to 4 with the LEDs I'm using.

The current swings going from 12-15 volts are dependant on (VS - VL) / R. As long as this doesn't exceed the ratings of the LEDs, you're fine. A 12 volt battery bank is a clean and stable power source. If I was powering an LED from a noisy power source, I would add a capacitor across the voltage supply and maybe a smaller one across the resistor to dampen voltage and current spikes.

bmet · November 2010

Let me ask the stupid question... 12v car lights?

How much current does a typical halogen bulb, made for auto headlight use? I understand that the reflector does a majority of the illumination, but the bulb is still very bright. How wasteful are they?

BB. · November 2010

Re: 12v LED w/traditional screw in connect available?

In the US, I believe our head lights are 55 Watts maximum although you may find 45 watt low beam halogens too.

55 watts / 12 volts = 4.6 amps

From the Wiki on headlamps:

The first halogen bulb for vehicle use, the H1, was introduced in 1962 by a consortium of European bulb and headlamp makers. This bulb has a single axial filament that consumes 55 watts at 12.0 volts, and produces 1550 lumens ±15% when operated at 13.2 V. H2 (55 W @ 12.0 V, 1820 lm @ 13.2 V) followed in 1964, and the transverse-filament H3 (55 W @ 12.0 V, 1450 lm ±15%) in 1966. H1 still sees wide use in low beams, high beams and auxiliary foglamp and driving lamps, as does H3. The H2 does not see wide use any more because it requires an intricate bulb holder interface to the lamp, has a short life and is difficult to handle. For those reasons, H2 was withdrawn from ECE Regulation 37 for use in new lamp designs (though H2 bulbs are still manufactured for replacement purposes in existing lamps). The use of H1 and H3 bulbs was legalised in the United States in 1997. More recent single-filament bulb designs include the H7 (55 W @ 12.0 V, 1500 lm ±10% @ 13.2 V), H8 (35 W @ 12.0 V, 800 lm ±15% @ 13.2 V), H9 (65 W @ 12.0 V, 2100 lm ±10% @ 13.2 V), and H11 (55 W @ 12.0 V, 1350 lm ±10% @ 13.2 V). 24-volt versions of many bulb types are available for use in trucks, buses, and other commercial and military vehicles.

-Bill

MisterB · November 2010

Re: 12v LED w/traditional screw in connect available?

I've been looking through my notebooks and I found where I put resistor values for LED circuits. For 1 5mm 20ma LED in a 12v circuit, I have 470 ohms, for 2 LEDs in series, 330 ohms and for 4 in series, 10 ohms with a note by this value that I am biasing for 17.5ma and the 20ma is a maximum value. I made 3 lights with this circuit that have been working for about 3 years now. I worked out the math from whatever spec sheet came with the LEDs and I bread boarded and tested the circuits before I made lights with them.

LED lighting, if done right, is by far the most energy effecient. When I measure the temperature on the surface of the light, my 17.5ma 12 volt lights are 2-3 degrees F above ambient temperature. A 12 volt flashlight with a 1 watt incandescent bulb is around 10 degrees F above ambient temperature and a 10 watt 12 volt halogen light is around 80+ degrees F above ambient temperature.

bmet · November 2010

Re: 12v LED w/traditional screw in connect available?

BB. wrote: »

In the US, I believe our head lights are 55 Watts maximum although you may find 45 watt low beam halogens
-Bill

Thank you for that reference, BB . My tongue-n-cheek response is that a 45 watt DC halogen doesn't sound too much worse than a 23 watt A/C compact florescent running of an inverter.

BB. · November 2010

Re: 12v LED w/traditional screw in connect available?

It is a matter of degrees--I usually end up with CFL for area lighting and desk/floor lamps for spot lighting.

But--I am on grid--so it is just couple dollars a month more for one choice over another.

-Bill

waynefromnscanada · November 2010

Re: 12v LED w/traditional screw in connect available?

RCinFLA wrote: »

You cannot push the limit on LED stack being so close to battery voltage due to variation in battery voltage across the range of absorb charge to minimum battery discharge voltage. That is 12.3vdc to 14.5 vdc, not including possible equilizing to 15+ vdc.
12 vdc supply with 10 ohms and 20 mA is 0.2 vdc of ballast voltage, almost nothing. If you had 20 mA at 12vdc that is 2.95 vdc per LED. Take that up to 14.5 vdc and you would have like over 200 mA. Actually you would not as one of the LED's would have blown before the charger got to absorb level.

I've had personal experience converting 120 volt LED "bulbs" to 12 VDC, splitting up the 120 volt string of LEDs, connecting the split strings in parallel through a 10 ohm ballast resistor to 12 volts. They worked fine for a while, then in every case (I did 5) they suffered early failure. Probably got only a couple hundred hours out of them. Obviously they were getting pushed too hard. Meanwhile, the identical 120 volt ones used in outside lights, now have probably 2000 hours on them with no sign of problems yet. And yes, I did work out the current etc that had to be dropped for 13.8 volt use, and never turned them on during the day when voltages would be higher. I think I was using 4 LEDs per string. Obviously too many and not enough ballast. Now I just use 120 volt ones, the inverter is on anyway.

MisterB · November 2010

Re: 12v LED w/traditional screw in connect available?

waynefromnscanada wrote: »

connecting the split strings in parallel through a 10 ohm ballast resistor to 12 volts.

Did you put a 10 ohm resistor on each string? Connecting the strings in parallel to 1 10 ohm resistor would lead to failure. Each parallel string of resistors needs it's own ballast resistor. I made several different LED lights with different LEDs and the ones that have lasted have been the 4 20ma LEDs in series with a 10 ohm resitor and a couple of lights with 2 80 ma 10mm LEDs with a 100 ohm ballast resistor. I'm always forgeting to turn them off before leaving home so both have been exposed to the full voltage range of my system.

waynefromnscanada · November 2010

Re: 12v LED w/traditional screw in connect available?

That, Mister B, is most likely where I went wrong. There would have been a slight current imbalance in the LED strings, which led to early failure of one string, after which the rest were quick to follow. May try it again, fewer LEDs per string, and an individual ballast resistor for each string. But with resistor power losses, and the fact that in my case the inverter is always on anyway, probably not worth the bother, except as a learning experience.
Still, it's kind of nice to have a few 12 volt lights in case the inverter shuts down for any reason.:p

BB. · November 2010

Re: 12v LED w/traditional screw in connect available?

Yea... You cannot parallel LED's with one ballast source... The LED forward voltage falls with increasing temperature--So as one string gets a little hotter, it draws more current, and gets hotter yet--drawing more current.

-Bill

MisterB · November 2010

Re: 12v LED w/traditional screw in connect available?

waynefromnscanada wrote: »

probably not worth the bother, except as a learning experience.
Still, it's kind of nice to have a few 12 volt lights in case the inverter shuts down for any reason.:p

That's my experience with making my own LED lights. The price has dropped a lot for LED bulbs and now I'm getting ready to install some GU10 lights that I can use either with 20 watt halogen or LED bulbs.

Using the smallest ballast resistor posible was a one of my goals when I was making them because of the basic electrical formula, Watts=I2*R--thats current squared times resistance, this laptop doesn't do math symbols right. The lower the resistance, the more power goes into making light and less goes into heating up the resistor.

BB. · November 2010

Re: 12v LED w/traditional screw in connect available?

I write that as: I^2 * R here.

-Bill

waynefromnscanada · November 2010

Re: 12v LED w/traditional screw in connect available?

BB. wrote: »

Yea... You cannot parallel LED's with one ballast source... The LED forward voltage falls with increasing temperature--So as one string gets a little hotter, it draws more current, and gets hotter yet--drawing more current.

-Bill

I knew that. Why didn't I take it into consideration? Guess I must have been having what an elderly (more elderly than me Haha) neighbor of mine calls "a brain fart".

Thanks for opening my eyes. In future, I'll do a better job

A day when one learns something is a day well spent. And I've sure learned a lot from this form over the years!

notsobright · November 2010

Re: 12v LED w/traditional screw in connect available?

lots of LED info to digest but with so many other DIY projects I think I may try one of these out for now but thanks for all the info and yes the candlepowerforums seems to have more info on the subject than anywhere. their info on small rechargable batteries and chargers is second to none also.

http://www.ledtrailerlights.com/rv/RV-1141mega.htm

Ive read on the RV forums that it is bright enough to read with from 15-20' away. output is 300 lumens.

rafaelito · December 2010

Re: 12v LED w/traditional screw in connect available?

Home Depot has some good inexpensive track lighting and fixtures with removable transformers. It's easy to use these components, gut the transformers as mentioned earlier (I chose to add a SPST push button switch) cutting tracks to fit various applications in our RV.

I used the 3 LED, 3W 12vdc Phillips Optima warm (3200 deg) MR-16 lamps and also retrofitted 2 puck lamps recessed in the ceiling with same off shelf Home Depot lamps. The total cost was about equal to the NAWS price for one Kyocera 135 W panel, and eliminates the need for it!

You can get crazy with the abundance of fixtures (and pricepoints) available online, but I chose HD stuff because of the local availability of replacements.

The light is excellent and very bright, though somewhat more directional, an advantage in my application since the fixtures swivel, are within easy reach and can be relocated, combined along the tracks, etc. Definitely a fun and doable project with immediate benefits. If I can tame me electrical needs to fit my 2 existing panels and 210 amp hour battery I will save some weight, critical in my application.

MaineOFFGRID · December 2010

Re: 12v LED w/traditional screw in connect available?

i found some sweet recessed led lighting

http://www.goodmart.com/pdfs/american/LMS.pdf

going to outfit my whole house with these things.

Tricksailing · January 2012

Re: 12v LED w/traditional screw in connect available?

This company has some good products http://www.lunasealighting.com/. I've used their replacement bayonet and 2-prong LEDs for a variety of lighting and been pleased with the results. Some as bright as the halogen bulbs they replaced. Also, it's getting easier to find MR16 LED bulbs, even in chain retail outlets. It's a challenge to find non-track lighting fittings for them, but you can buy the bare sockets at electrical stores if you have the skill to make your own fittings.

This is another company that has a lesser selection but includes Edison-type screw-in bulbs and also light fixtures http://doctorled.com. Most seem to be relatively low output but they are good enough to read by.

12v LED w/traditional screw in connect available?

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