Led bulb safety

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Oscarpop

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Am in the process of changing my halogen bulbs on my boat to led .

My friend in the pub tonight says that unless you have bulbs that are able to tolerate voltages that are about 14v, you risk setting fire to your boat.

Bought mine on amazon at £6 a pop. It does however say that they last longer if you have a steady voltage

. There is also some evidence on google that cheap LEDs can cause problems when voltage is variable.

What is the truth?
 
Maybe ask Old Varnish when he gets back

http://www.sailblogs.com/member/wildsong/?xjMsgID=267298

Becalmed again
April 14, 2013, 12:22 pm
Slow in Horse lats after 2 good days. Motoring. Distance to Horta 805 miles.
Now in centre of high, glassy calm, hope W winds not far north of me now. V poor progress though, five miles in last 9 hours, dare not use more diesel. Fuel carefully planned.Got strategic reserve of 100 miles still in cans. Very little sleep,sails slatting noisily, rolling in swell if I take the main off . Also had small fire on board- light fitting overheated..
Boat more sluggish- pray for scrub in Horta . Food very boring. One apple and two onions left of the fresh stuff. On we go.
Click to expand...
 
Most cheap LED bulbs use a resistive current limiter. The resistor is selected for operation in a car at 31.75 to 14v on charge. Certainly and electronic current control is better for constant brightness across a range of input voltages. These are indicated often by the quoting of input voltage typically 10 to 30 volts. However the electronic current control costs more.
I don't believe there is much danger of a fire from a resistive current limited LED bub. If you are concerned you might ensure that there is no flamable material in close proximity to the bulb. Generally if the bulb is internal you will be nearby if it is operating so would smell trouble. Further it is most likely that when you have the bulb on you would not be charging the battery which is the source of high voltage. Even if you are using a shore power charger it is most likely the charger will not be on the high current phase.
If you do use a shore charger and are concerned about using cheap LED bulbs then you can add more resistance to the wiring to limit the current. Albeit with a slightly lower light output on low battery voltage. A typical bulb might draw .25 amp so an additional resistor of 4 ohms will drop 1 volt. (wasting .25 watts so get a 1w resistor.
Having regard to the above considerations I believe the cheap bulbs are very viable for internal cabin lights for a boat. They are very cheap from China. I have many in operation around home. (12v security lighting) as well as on the boat. no concerns or failures.
Where I have been disappointed with failures is so called corn cob or spot light domestic mains powered lights. I assumed 220 volt rating was ok where we have 250 volt power. The circuitry for these bulbs having typically 108 LEDs is pretty crude having 54 in series from a simple rectifier and capacitive current limit. They failed pretty quickly. One LED dead kills all. The type rated 90 to 250v AC or similar have electronic current limiting often to just 3 high powered LED are far better. digressing here but a warning.

So for the boat yes electronic current limited LED bulbs are better. But the cheap ones are so cheap to do the same job. We don't all drive Rolls Royce cars but a salesman for a RR will be quick to point out the unsafe nature of cheap cars implying that you would be crazy to buy a Vauxhall or Ford. good luck olewill
 
William_H said:
If you do use a shore charger and are concerned about using cheap LED bulbs then you can add more resistance to the wiring to limit the current. Albeit with a slightly lower light output on low battery voltage. A typical bulb might draw .25 amp so an additional resistor of 4 ohms will drop 1 volt. (wasting .25 watts so get a 1w resistor...
Click to expand...

A typical LED chain will draw about 1/10 of that: 25mA, so a 4R resistor will do very little, try 47R.
 
Cheap LEDs are normally fine for internal lighting, there is very little chance of a fire as they are a cool light. There is probably more chance of a fire from a halogen bulb as they get really hot. Cheap LEDs might fail a bit sooner than a very expensive one with an electronic controller. Buy cheap, probably buy twice and still pay less than buying a more expensive LED with an electronic controller. Unless the electronic controller is properly sealed and marinised it might not like the salt air or even a big splosh off your foulies when coming below in heavy seas, or the unexpected leak in the coach roof, so it might fail just as quickly.

I build all my own LED lighting, it is cheap and very easy if you only use resistive circuits rather than electronic control. When they eventually fail I will make new ones for far less money that perform much better and use less current than the ones I built 2 years ago.

My first LED light was a headtorch when I was caving 14 years ago, when high intensity LEDs were only just coming onto the market. At the time it was better than anything else available on the market now it is about as good as most things on the market. It has been bashed filled with muddy water, washed out, used until the batteries ran out and the LEDs were so dim that I could only just see, used when it had just come off charge (I could charge it in the car on the way) so the voltage was way too high and the LEDs were blinding. One of the LEDs is a little dimmer than the rest, but other than that it still works just as well as it did 14 years ago, I wish I could say the same about me!

At the time I paid £3.50 for each LED, now I pay £0.16 per LED for something that is much brighter, uses far less power and has a much better angle of field.

You pays your money and takes your choice.

Ross
 
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