# New led downlighter conversions won't work??



## krull (Jul 22, 2006)

I just bought a pack of 6x MR11 LED downlghters for my vanoff ebay. They were to replace the little halogen 10w bulb and reflector units completely.

Trouble is they won't work on 12v DC. 

They work on the house 12v AC system but in the van when connected they flash brightly than go very dim. They still work in the house. 

Anyone know why this would happen and can you get around it?

Obviously there is the difference between AC and DC, but as they are diodes,I thought it was just a question of connecting them to the correct polarity.

Thanks


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## JohnsCrossMotorHomes (Jul 21, 2007)

krull said:


> I just bought a pack of 6x MR11 LED downlghters for my vanoff ebay. They were to replace the little halogen 10w bulb and reflector units completely.
> 
> Trouble is they won't work on 12v DC.
> 
> ...


Hi, not being a full blown techie, I would imagine that as you say they will not work on DC voltage as the transformer produces 12v AC

The old ones in the van are 12v bulbs, not diodes, perhaps the solution is to buy standard MH, marine or caravan Krypton bulb downlighters and fit those and put your ebay ones back on Ebay.

Alternatively you could use an inverter to produce 12v AC but then it all gets expensive and complicated.


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## maddie (Jan 4, 2006)

Hi with my little knowledge on electrical stuff & spelling I do not think that they tranform to 12v AC, they all go from 240v ac to 12v dc so your problem will not be that,unless somone knows different?
plus it gets back to the top untill a better sugestion comes along
terry


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## 107506 (Oct 7, 2007)

Hi I'm a sparky so may be able to help as said, transformers turn 240v ac into 12v dc. As your van is also 12v dc this sounds odd unless there is a slight fault in your van that a normal lamp didn't pick up, but as led's are electronic they are more sensitive so may have picked up a fault.

Hope this helps Russ


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## 107558 (Oct 10, 2007)

LEDs are very sensitive to voltage anomallies. They should be on a 12v DC Regulated supply.

With LEDs close only counts in handgrenades it must be exact.


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## Melly (Jul 5, 2007)

Would it not be possible to connect one direct to a 12V battery and if it works ok on that it is probably a fault on the van elecrtics maybe on the earth side.


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## JohnsCrossMotorHomes (Jul 21, 2007)

Rusky said:


> Hi I'm a sparky so may be able to help as said, transformers turn 240v ac into 12v dc. As your van is also 12v dc this sounds odd unless there is a slight fault in your van that a normal lamp didn't pick up, but as led's are electronic they are more sensitive so may have picked up a fault.
> 
> Hope this helps Russ


Russ,

With respect a transformer can only step UP or DOWN an AC voltage, it cannot change AC into DC.

''By appropriate selection of the numbers of turns, a transformer thus allows an alternating voltage to be stepped up - by making NS more than NP - or stepped down, by making it less.''
http://en.wikipedia.org/wiki/Transformer

Regards


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## blondy (Aug 23, 2007)

*LED LIGHTS*

I think you will find there are 2 types of L E D, one for vehicles like M/Hs
which have something built in so they work, the others you need somthing to make them work, sorry bit vague, age and memory, and all that.
Cheers Don


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## sallytrafic (Jan 17, 2006)

Most of the replacement LEDs intended for motorhomes have small regulators built in. I think the ones in house systems may be designed to run on 12 or 15V ac and be fed with a capacitor in circuit. The capacitor charging may be what causes the flash, once charged the light would go out.

One to act as halogen replacements are shown on this website along with the ones they can replace.>CLICK HERE<


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## 107506 (Oct 7, 2007)

Hi JohnsCrossMotorHomes, I was trying to keep it simple by saying that you plug in the black box which is loosley termed the transformer or power pack and out comes 12vdc. I know that you also need a bridge rectifier circuit which converts ac to dc , but as this is built in I didn't bother to go into it , sorry for any misunderstanding caused!

Regards Russ


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## DJP (May 9, 2005)

> I just bought a pack of 6x MR11 LED downlghters for my vanoff ebay. They were to replace the little halogen 10w bulb and reflector units completely.


I also bought some LED's off Ebay for my van and they work perfectly. These were also MR11's. I did actually buy 12 and sold 6 to another van owner. His also work ok. Sorry this is not what you wanted to hear, but it may indicate the fault is within your van  


> They work on the house 12v AC system but in the van when connected they flash brightly than go very dim. They still work in the house.


 Assuming it is 12 v DC via a transformer should say the lamps are ok also. Check the state/condition of the leisure batteries in the van. Does everything else work ok? What happens if you just fit one MR11 and switch it on? Do the old halogen lamps still work ok in the van?
Denns


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## krull (Jul 22, 2006)

Thanks for all your replies chaps. Here's an update:

Typo error, they are MR16's not MR11's.

The ebay ad says ac/dc, the bulb says ac 50hz.

The leisure batteies are 1 week old and were reading 13v.

I tried them on a different fitting and hey presto, they work!

However the light was not very bright to say the least. I bought them for a two week trip to Orkney in January where there is only 6hrs daylight and wildcamping only. However, I don't honsestly think they will be bright enough. Also the light is very cold.

As I have just added a second 85AH leisure battey, I might just chance it and use my tiny 300 watt EX350 Honda generator if needs must. Trouble is all these toys such as sat tv! Last time we went to Scotland in January TV wasn't a problem as we could never receive terrestial!


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## gaspode (May 9, 2005)

I'm convinced that the only way to buy LED bulbs is to see them working before you buy.

There are different types for AC and DC useage, LEDs are always DC but when used in a domestic situation they have to run on 12v AC (the standard halogen transformers do not have rectifiers built in so are 12v AC output) so I presume the makers incorporate a capacitor as someone has already said, this will preclude12v DC operation. Automotive LEDs will run on DC just fine.

Just because there are 48 LEDs in a bulb as opposed to 21 doesn't necessarily mean they will be brighter, it also depends on the individual LED output, as a rough guide go for a bulb with a 1 to 2 watt rating. Colour temperature is also a problem. Ideally for M/H use you should have a colour of less than 3500k but most sellers don't even know what temperature their LEDs are, they just describe them as "white" or "warm white" which can cover a multitude of sins from blue to green. The other thing to watch is the angle of beam, for a M/H you need a very wide angle (80 deg+) narrow angle lamps will be useless for overall illumination.

My advice is to try before you buy - or buy from a reputable UK seller who will change them if they aren't suitable - and if the seller can't tell you the beam angle and colour temperature go somewhere else.


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## alunj (Sep 5, 2007)

This place has a good range WWW.DEL-KO.DE
All of the bulbs have angle and wattage specified. 
I just order one of each type I was interesed in to check if OK before jumping in with the rest. As usual we seem to be paying well over the odds in the UK


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## Boff (May 10, 2005)

Hi,

keep in mind that the letter D in LED stands for "Diode". And a diode is by definition a "one-way-valve" for electrical current. So you might want to try running them in your van with the polarity reversed.

Regarding brightness: Only the very latest LED models can actually exceed ordinary halogen lamps in terms of luminous efficacy. I do not expect these to be available in cheap halogen replacements at ebay yet. So if you want to reduce power consumption while maintaining brightness, either spend a lot of money on top-quality LEDs, or switch over to fluorescent lights. They are still significantly better than commercially available LEDs, and far cheaper.

Best Regards,
Gerhard


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