12v LEDs instead of halogen

[chris w]

I find the flicker (50Hz or 25Hz or even 100hz? Someone will tell me.) rather trying. You don't get that with incandescents because the filament can't cool down quickly enough, but I haven't been on a boat which is fitted with them so modern ones might be better than the gangway illuminators in our local cinema.

 

How do you find the type of light that you get with them?

 

Nick

It's a 100Hz flicker if you run them off normal 50Hz mains (through a transformer obviously). Yoy won't get flicker if you run them directly from the batteries (through a series resistor)

 

Chris

[old what]

I've just fitted 25 LED lights throughout the boat and although it's early days I'm very impressed with the level of lighting and the mood they create. I was initially concerned that the light would be cold; it's not quite a warm light but it is very relaxing.

[tomandsophie]

I've just fitted 25 LED lights throughout the boat and although it's early days I'm very impressed with the level of lighting and the mood they create. I was initially concerned that the light would be cold; it's not quite a warm light but it is very relaxing.

 

How have you overcome the possible problem of the LEDs going out over time? Have you got a DC-DC converter/regulator thingy? What kind of LEDs did you buy?

[old what]

They've only been in a week and touch wood they appear to be okay but I couldn't understand was they didn't appear to be positive and negative sensitive and I always thought that LEDs be a diode needed to be connected correctly?

[chris w]

They've only been in a week and touch wood they appear to be okay but I couldn't understand was they didn't appear to be positive and negative sensitive and I always thought that LEDs be a diode needed to be connected correctly?

 

LEDs are polarity sensitive and will only work one way round. However, there are some very simple electronic tricks that one can play to make them polarity insensitive and also insensitive to over-voltage.

 

The bit needed to do this is called a "bridge rectifier" which consists of 4 tiny diodes wired in a special configuration; it's about the size of a small aspirin and costs around 30 pence from Maplin! Further, it has the property that it will reduce the voltage on the LEDs by about 1.5v from that applied (ie: 12v applied would give 10.5v at the LED; 14.5v applied would give 13v at the LED). With a suitable series resistor in line with each LED (say 1K ohms @ 8 pence each) you could run a few dozen hi-brightness LEDs from the one bridge rectifier. (Note that the LED itself also drops about 2v across it).

 

As the applied voltage can vary from say 12v (battery only) to a maximum of say 15v (charger on) the LEDs will vary slightly in brightness, depending on which source of voltage one is using, but with the correct choice of series resistor, you won't notice any significant difference.

 

The ones that come with an AC transformer have exactly this circuit but with the addition of a voltage regulator chip and a couple of small capacitors (another 50 pence total) to pin the voltage to 12v at the LED. The great thing is that the bridge rectifier also converts the AC to DC. One could easily run 40 or 50 individual LEDs off the one circuit.

 

The price one pays for a commercial unit is an absolute rip-off as that's all there is to it. If anyone's interested I'll post a circuit on the Forum.

 

Chris

Edited January 25, 2007 by chris w

[Theo]

It's a 100Hz flicker if you run them off normal 50Hz mains (through a transformer obviously). Yoy won't get flicker if you run them directly from the batteries (through a series resistor)

 

Chris

 

I feel rather foolish! Of course you won't!

 

Nick

[tomandsophie]

The price one pays for a commercial unit is an absolute rip-off as that's all there is to it. If anyone's interested I'll post a circuit on the Forum.

 

Chris

 

Thanks for the info Chris - sounds a bit too complicated for my little non-electronically-minded brain! A circuit on the forum would be great.

[nickelodeus]

Hmm....

 

I've just stuck four LEDs from screwfix under the gunwhales in the bedroom.....they look really cool and I just leave em on most of the time...they're just connected straight to the 12v system.

 

Slightly worried though if there's a stability problem....they all seem to be working at the moment but they've only been in a couple of months - don't really wanna have to replace em!

 

So do we have a verdict? Is the general consensus that if I leave em connected in this way, they're sexy illuminating days are numbered?

 

Nic

[chris w]

Hmm....

 

I've just stuck four LEDs from screwfix under the gunwhales in the bedroom.....they look really cool and I just leave em on most of the time...they're just connected straight to the 12v system.

 

Slightly worried though if there's a stability problem....they all seem to be working at the moment but they've only been in a couple of months - don't really wanna have to replace em!

 

So do we have a verdict? Is the general consensus that if I leave em connected in this way, they're sexy illuminating days are numbered?

 

Nic

 

No reason to suppose that. LEDs have a huge life - many tens of thousands of hours. The weak points will be the mechanical construction of the final "package" and therefore the integrity of the internal connections etc not the LED itself.

 

The LED package will have a series resistor incorporated - probably specified at something like 10mA @ 12v. (Ultrabrite LEDs need a lot less current than conventional panel indicator LEDs). So if the voltage rose to 15v say when the charger's on, the current would rise to 13mA which is not going to harm the LED at all. It will appear a little brighter that's all.

 

Chris

[Guest Trevor George]

. . . Slightly worried though if there's a stability problem....they all seem to be working at the moment.

Some have built-in regulators into the units . . . . like THESE

[john & mike]

Hi Guys, I am a sailor not canal boater but have logged into this forum for help with heating.

 

In answer to the led issue i have fitted them aboard my sailboat and they are fantastic, the ones i have used are regulated to work from 10v to 15v so no probs with blowing up !

 

i got mine from http://www.ultraleds.co.uk/ and they come in a variety of sizes shapes and colours including a warm white which is what i have used and although they do not give off as much light as halogens they only draw 1.6watts each so you can afford to use loads (if you can afford them ! they are between £6 and £9 each depending on how many you buy )

 

Hope this helps

[Lesd]

This thread seemed fade away which was a shame sothought Id apply a small kick. Do any of the members who have experimented with LEDs have any further updates ?

 

My boat will be fitted out over the summer and Im considering using LEDs rather than halogens but Im worried about two things;

 

1. Coverage compared to halogens. Will a standard spread of ceiling downlighters (designed for halogen) but ok when equipped with replacement led clusters or will I need more downlighters to achieve a reasonable amount of light ?

 

2. Are the standard LED clusters safe to use on boat systems with upto 15v during charging cycles ? Chris had mentioned they were fitted with current limiting resistor but I know Tom and others had early problems with failures.

 

Any info anyone can pass on would be much apreciated.

Rgds

les

[Gary Peacock]

These are some of the new generation LED lights we are now supplying-

 

 

 

 

They have a operating voltage of 9-15V DC

 

The dome light draws 0.14 Amps at 12V and incorporates a lower output night light circuit.

 

The Mini down light draws 0.06Amps at 12V

 

This is only two lights of a fairly extensive range also including IP66 deck lights and strip lights intended to be used in place of fluorescent fittings.

 

These are the first LED's at sensible prices that I feel are a true alternative to conventional lighting.

[Lesd]

Hi Gary,

Thanks for that, where can I see more info and prices on the range ? can you post a link ?

Rgds

Les

[Gary Peacock]

I should be getting the pictures done and the details on the website soon, I can give you some idea of the prices etc if you drop me a message.

[arpeeuk]

I replaced one of my MR16 halogens with one of these

http://www.ultraleds.co.uk/mr16-acdc-warm-...gle-p-1166.html

about 6 months ago.

Before I purchased I asked the supplier about the high voltage issue when charging and was told that there would be no problem upto 15V.

I'm delighted with it and have subsequently replaced another 4 bulbs.

 

Also got one of their head torches, fantastic for delving into the engine bay etc well worth the tenner