The great LED ripoff

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nathanlee

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I'm getting to the point of needing to start fitting lights in my new boat, and I want to go with LED's. However, as well all know, marine LEDs are an absolute rip off.

ebay is full of much cheaper (circa £8) light units, but they have a drawback. They need a 12v (exactly) supply, and deviations outside of this reduce their lifespan, which is the standard line you'll get from any marine LED retailer trying to flog you their £60 light.

So, I had a thought, and wondered if a electronics guru (David?) can advise. Back in the day, when I used to play with soldering irons, I often used a 5v regulator chip. Well, how about using a central smoother circuit near the boat switch panel, and regulating the supply of 12v to the cheap(er) LEDs?

http://uk.rs-online.com/web/p/linear-regulator/0453568/

£3.65 from RS components. That one will handle up to 3amps, or £14 for a more realistic 7.5amp chip. 7.5amps is a lot of LEDs.

Sound like a reasonable solution?

Cheers,

Nathan
 
as you are starting from basics (?) what about a 12v regulated supply, as used for solar panels, just downstream of the battery ?


http://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=m570.l2736&_nkw=12v+regulator


Would that give you a proper, stable 12v circuit, or will you lose voltage in the cable to the (distant ) sharp end of the boat ?


I have a feeling that a cheap and sensible answer is lurking somewhere, - but perhaps not in this reply :o


EDIT
I hav ejust seen this device - seems to answer the question ?

http://www.ebay.co.uk/itm/12-VOLT-R...4235454?pt=UK_Light_Bulbs&hash=item416437893e
 
I picked up a couple of LED festoon bulbs from Halfords. 8 quid for 2 just to try in the cabin light fittings. They're great. A bit brighter light than before even with the plastic diffuser fitted. They were that good I purchased 4 more to do the other lights in the boat. Good thing with the festoon fitting is that you twist the bulb in the fitting to give a more even spread.

There is a lot less drain on the battery so the solar panel, which is a bit too big really, has no problems at all keeping the battery charged.
 
nathanlee said:
That EXACTLY what I was suggesting I make. For £4.49, it's cheaper that I can buy the components for. Good find. Thank you :)
Click to expand...

You´ll lose a bit of voltage, the RS one was 350mV, not a prob if you´re plugged in, maybe not very noticeable even if the batts get down to near 12v.
 
nathanlee said:
ebay is full of much cheaper (circa £8) light units, but they have a drawback. They need a 12v (exactly) supply, and deviations outside of this reduce their lifespan...
Click to expand...

A domestic MR16 SM LED light is designed to cope with a switch mode transformer that costs less than £3 and which is unlikely to do anything exactly.

The bulbs contain everything needed to protect the LEDs.

The only downside is they don't give any warning that the battery is nearly flat. Mine seem to run from 6 to 14.8 volts with no change in brightness.
 
I saw these folks at a boat show a while back.

http://www.prebit.de/index.php?option=com_content&task=view&id=57&Itemid=83&lang=en

Really, really nice looking lights, but really, really not nicely priced. If I recall correctly, a single down light was about £80!

There's just one light on the boat that needs to look really special. She's having an oak galley worktop, so I need (no, shame on me - want) a good reading light to give it some wow factor.

Not £80 of wow though. Possibly a normal reading light with an LED replacement bulb.
 
Building your own is generally cheaper, but make sure you have an efficient circuit. The beauty of LEDs is their low power consumption, it's easy to convert 12v to lower voltage, but it's harder if you want to keep the efficiency high. You also need good transient protection, heat disipaton and little emf production. I have given up building my own circuits and now generally buy prebult modules.
By contrast there are considerable improvements by sourcing your own LEDs especially the higher powered 1 and 3w emmiters. Production lights tend to use old and inefficient LEDs with poor colour. Modern emitters will often be double the brightness for the same power consumption and heat production.
Building your own LEDs will generally result in a better product. Brighter, less power consumption and much better colour temperature. You can also make, or adapt, nicer housings than the cheap plastic offered in production lights, but it's hard to save much money compared to the Chinese products.
 
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to do it properly, a bucking chip won't do it as it may well need 0.7v above the regulated value (12v). also something more efficient than a typical 7812 too.
 
Like most things, you usually get what you pay for. Cheapo LEDs will provide a cheapo solution. I can recommend Aten Lighting ( they have a website). Good kit, sound advice, not the cheapest but more of a guaranteed result.
 
Regulator for LEDs

As said the regulator will drop your supply by a minimum 350mv so if the battery voltage drops to 12v you will only get 11.65 volts to the LEDs. When battery voltage is 12.35v and above you will get 12v for LEDs.
The standard 7812 regulator is much worse losing about 2.5 volts.

I have found the Chinese LEDs cheap and apparently designed for automotive use. ie for a max 13.75 volt supply. I have go the impression that they are under rated such that from my test 15v no problem.
however if you anticipate using them on 15v you can just add another series resistor to reduce the voltage.
For a 100ma bulb a 20 ohm resistor will reduce the current and voltage nicely. 15v down to 13v.
Resistive current limiting is cheap and free of radio interference and being low parts/ complexity count more reliable.
For nav lights I would strongly reccomend purpose built LED nav lights as it is difficult to get angle conformity and colour with LED bulbs.
Go LED but go cheapest olewill (I don't drive a Rolls Royce either.)
 
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