A low cost LED lamp for your anchor light - some test results

Steve Clayton said:
I don't see where "Blue Chip" was referring to a Davis light lamp ???

However: referring to this on your site:
NEW VERY BRIGHT LED ANCHOR BULB - CONVERT TO DUSK TO DAWN

This unique marine product is an automatic daylight sensing replacement 15-LED bulb, which automatically comes on at dusk, and turns off again at dawn. It is a simple drop in replacement for your existing Aqua Signal, Hella, Perko or other anchor light.

Then it is £16.65 plus shipping
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Some confusion is afoot!
The Davis Megga Light is fitted with a so called minature BA9S incandescent bulb. This thread is a discussion on the merrits of buying low-cost BA9S LED lamps from Hong Kong vis-a-vis higher priced UK supplied lamps.
The product you quoted as http://www.boatlamps.co.uk/contents/en-uk/d85.html priced at £16.65 is for a BAY15D lamp which is a much larger lamp with a built-in light sensor cell. This product is not designed to fit the Davis Megga Light. Its for the much larger anchor lights manufactured by Hella And Aqua Signal. It actually allows boat owners to convert existing anchor lights into dusk to dawn lights by a simple change of bulb. I hope that clarifies matters.
Regards
 
I did actuallly check the price of the lamp last night before posting, it seems I got te price from the wrong lamp, my apologies for that.

However my post wasn't directed at this supplier specifically, I only used that as an example of the savings that can be made by looking at alternative suppliers.

The video of the lamp smoking at 14.8V was interesting, as I have a spare LED (I got 2 for 99p) I'll repeat that test tonight and see what happens to mine.

I have fitted low cost LED's throughout my boat earlier this year and use a Sterling 50A smart charger, it's not inconceivable that I have those sort of voltages present when on shore power- I've seen no signs of any lamps smoking or failing so far.
I have some spares of those lamps also - more testing required I think, but that will have to wait until next week.
 
Resistor controlled lamps are designed for motor vehicles, this is the type of lamp you have purchased. The rating of resistor can vary from manufacturer to manufacturer in terms of its resistance and wattage. If your lucky the lamp has actually been designed for a supply voltage of 14 or 15 Volts. That means a couple of things, the first is that the lamp will be less bright i.e. It will have a lower Lumen output value than a constant current lamp when operating at 12 volts. The lamp will be around 25% less bright at 12v than it would be at 15v. That fine when the lamp is on the back of your motor bike but not so clever in poor visibility anchored at sea! The whole point of LED lighting is more light output per watt. The more worrying second point is if a manufacturer uses a resistor to maximise light output for say 12 volts, guess what? at 14-15 volts it's potentially as the video illustrates a fire risk. The fact is you don't know what control resistors are fitted to these cheap lamps. You may be fortunate others may not be. What I can assure you is that the cost of the control circuits contained in my lamps actually cost more that the total price of your Hong Kong Lamp. In my world you don't get nothing for nothing.

I think Clint Eastwood summed it up When he asked 'do you feel lucky'

LED lamps are current sensitive devices and as such the light output will reduce when a low voltage is applied and get brighter when a higher voltage is applied. A rule of thumb is For every 10deg increase in heat you get within an LED you actually get a 50% reduction in lamp life.
 
Adrian Jones said:
Resistor controlled lamps are designed for motor vehicles, this is the type of lamp you have purchased. .
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I dont understand that comment. The alternator regulator on my boat is exactly the same one as supplied for a car and will allow the charging voltage to go up to 14.5.

LEDs designed only to operate on a stabilised 12v system have to be for some other application.
 
Bosun Higgs said:
I dont understand that comment. The alternator regulator on my boat is exactly the same one as supplied for a car and will allow the charging voltage to go up to 14.5.

LEDs designed only to operate on a stabilised 12v system have to be for some other application.
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Perhaps he means cars are applications where wringing the last drop of efficiency out of a lighting unit isn't an issue ... ? (that's how I read it)
 
snooks said:
That's more than a bit worrying:eek:

Thanx
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It also worried me, so I set up an identical test rig this evening with one of my eBay LED's
I used identical conditions except my bulb is mounted in my anchor light as that's the only bulb holder that size that I have.
I'm powering the bulb at 14.8V - same as the video, it's now been running for 50 minutes - so far no smoke, no flames and the LED's havent fallen off.
I'll report back later
 
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I made a long and interesting (I thought) response to the original post but the system ate it. Anyone else had such problems recently?

Quick resume:
Bluechip will find the LEDs he purchased will be fine. No reason to suppose they won't. They will not burst into flames. They may provide less than 'legal' output - try a 9 LED cluster.
The Davis Mega light is a great piece of kit - I encourage you to add a 9LED cluster (or more) and use it as your anchor light.
If you have the widely distributed Chinese built copy of the Davis mega light your problem is not the light output it's the fact that they leak like a sieve. One downpour and they're toast.
I think the skipper should decide the effectiveness of his anchor light not some bloke in Brussels who's never been on a boat. My choice is an oil lamp, used one for six years full time cruising.
We can't sell an anchor light that doesn't comply with the appropriate European directive, not just electromagnetic compatibility but Colregs72, but some do. But, see above - use what you consider right. Garden lights - hmm, maybe not.
Commercial bit - we use the Chinese lens and body but modify the cable gland and O ring set up, we do a full immersion test, we have CE certficate of compliance.
I wonder if this will post?
 
BlueChip said:
It also worried me, so I set up an identical test rig this evening with one of my eBay LED's
I used identical conditions except my bulb is mounted in my anchor light as that's the only bulb holder that size that I have.
I'm powering the bulb at 14.8V - same as the video, it's now been running for 50 minutes - so far no smoke, no flames and the LED's havent fallen off.
I'll report back later
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If your ammeter is accurate and it reflects the current through your lamp. It is currently consuming power of over 3 watts, for 5050 SMD LEDs thats far too high and amount to LED abuse....ha. Is it flickering yet?

Its all about the brighter it is, the hotter it gets and the shorter is the service life. 3W is the same as one of my LED replacement lamps sold to replace 35Watt halogen down lights in my kitchen. That has a massive aluminium heat-sink on to cool it.
 
Salty John said:
I made a long and interesting (I thought) response to the original post but the system ate it. Anyone else had such problems recently?

Quick resume:
Bluechip will find the LEDs he purchased will be fine. No reason to suppose they won't. They will not burst into flames. They may provide less than 'legal' output - try a 9 LED cluster.
The Davis Mega light is a great piece of kit - I encourage you to add a 9LED cluster (or more) and use it as your anchor light.
If you have the widely distributed Chinese built copy of the Davis mega light your problem is not the light output it's the fact that they leak like a sieve. One downpour and they're toast.
I think the skipper should decide the effectiveness of his anchor light not some bloke in Brussels who's never been on a boat. My choice is an oil lamp, used one for six years full time cruising.
We can't sell an anchor light that doesn't comply with the appropriate European directive, not just electromagnetic compatibility but Colregs72, but some do. But, see above - use what you consider right. Garden lights - hmm, maybe not.
Commercial bit - we use the Chinese lens and body but modify the cable gland and O ring set up, we do a full immersion test, we have CE certficate of compliance.
I wonder if this will post?
Click to expand...

write in word,copy n paste if you loose it re-copy n paste

PS we have a Davey & Co copper anchor lamp + a Hella 10w to hoist in the fore triangle
 
The real problem here is that not every buyer of chinese products ensures they actually meet the specs before passing them on to the unsusopecting public. For what are relatively low cost items full quality control can have a very significant impact on cost, so most rely on statistical sampling and accept a certain small percentage of failure.

An interesting question no one has asked was how many lamps needed to be tested to get the dramatic Utube failure. The lack of any data on how they sampled makes that video completly valueless for assessing the safety of the unit they tested. In fact we only have their word it was a 12V device.
 
WayneS said:
Interesting article here

http://www.bedazzled.uk.com/Downloads/Special_Consideration_for_LEDs.pdf

Normal T&C - not related to company, not promoting their products etc etc. Just an interesting read
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A simple LED with resistive current limiting will in fact be very resistant to transient high voltages. Indeed many LED circuits pulse a high current for various reasons while maintaining average current hence heating is within specs. So transients I don't think will hurt an LED. However the transients can hurt electronics especially the current control circuit of a sophisticated LED driver. Or other electronics. There may be a case for a supression device ina boat but then if you havn't already had a failure why worry. I suspect the article's figure are worst case or even exagerated for effect. olewill
 
Adrian Jones said:
If your ammeter is accurate and it reflects the current through your lamp. It is currently consuming power of over 3 watts, for 5050 SMD LEDs thats far too high and amount to LED abuse....ha. Is it flickering yet?

Its all about the brighter it is, the hotter it gets and the shorter is the service life. 3W is the same as one of my LED replacement lamps sold to replace 35Watt halogen down lights in my kitchen. That has a massive aluminium heat-sink on to cool it.
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Maybe but its going into an anchor light and you dont run the engine all night at anchor. Plus at something like one tenth of the cost of the high price UK supply (which will be Chinese anyway) he can afford to have a shorter life bulb.

Should you not be trying to be more competitive and reducing your price and margin rather than knocking the competition?
 
Bosun Higgs said:
Maybe but its going into an anchor light and you dont run the engine all night at anchor. Plus at something like one tenth of the cost of the high price UK supply (which will be Chinese anyway) he can afford to have a shorter life bulb.

Should you not be trying to be more competitive and reducing your price and margin rather than knocking the competition?
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I'm sorry you think I'm knocking the competition and am very disappointed by your rather shallow and blinkered view of my motives.

I'm an engineer and attempting to highlight, constructively, I thought, issues raised. I entered the debate because my companies products were described as being expensive and my prices were incorrectly quoted making my products appear non competitive. I'll be frank and state that I don't actually give a stuff about whether people buy my products or my competitors. I do however, think its important for boat owners to be aware that there are differences between look-alike products and the differences are there for a reason. I think boat owners should not buy in ignorance of these differences.

Of course low cost resistor controlled lamps will work well when batteries are not being charged, that is obvious. The problem comes when lamps are left on, for all sorts of reasons, in error for instance. The boat is in its berth and a multi-stage battery charger is on and cycles charging voltages. Some of these give out in excess of 15.5 Volts when in equalisation mode. The debate actually should encompass all LED lamps used in a marine environment not just external anchor lamps where the risk, again obviously, is somewhat less than lamps buried in a boats internal structure. I have actually removed resistor controlled LED lamps which whilst still functioning have melted the plastic enclosure they were contained in. They were definitely a fire risk.

3 Watts is one hell of a power consumption for a relatively tiny 5 SMD LED BA9s Lamp on small non heat sink PCBs, even more so when it is enclosed in an enclosure, the lamp on test was in open air. That is a lot of heat being dispersed and LEDs don't like heat. For comparison a 6 SMD device mounted on a much larger thermal PCB has a typical power input of 1.2 Watts.

There is no doubt in my mind that the BA9S lamp on test will fail prematurely after progressively giving a reducing light output, the time scale I'm not sure about. I have ordered exactly the same lamps and will test them to destruction and report my observations to the forum.

I do hope engineers and others on this forum will contribute to the debate.
 
Adrian Jones said:
I do hope engineers and others on this forum will contribute to the debate.
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As an electronics engineer, I fully agree with what Adrian has said in this forum. Unless sized for the maximum supply voltage, resistors are not viable to use with LEDs in critical areas. There is also the danger of thermal runaway, caused by the characteristics of the LEDs. If the resistors are sized for the maximum voltage, then the light output at normal voltages will be greatly reduced. A simple circuit simply cannot cope with the wide variations in voltage, which can be 10V to 15V. Fitting a voltage regulator would help, but the losses override the benefits of using LEDs. The only way is to have "PWM, Buck Constant-Current electronics" as stated by Adrian as being in his products.

As an example, I built a PIR operated LED lamp for the saloon, using a dropper resistor in every chain of 3 LEDs. After much experimenting, I had to multiply my original estimate of the number of LEDs required by a factor of 10, to over 100! In this instance, the complexity of a more advanced circuit was not warranted, if a string of LEDs blows there is no real harm done, and the LEDs were still cheaper than the required control chip. In addition, the light is only on when it senses movement, and the other lights are off. There is no way I would use this method in a critical light.

I have no connection with Adrian or his company, but I do know what I'm talking about, for a change :rolleyes:
 
I agree resistor based regulation of LEDs on most boats works poorly.The voltage variation is too high. You have choose one from the below list
1. poor output
2. short life
3. High power consumption

With a few simple bits of electronics these compromises are avoided.
My advice would be only buy LEDs with some sort of regulation . They usually specify a wide voltage range ( say10-30v)
 
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