Frustrated Boater's Dim LED

[FORTUNATA]

I was asked to take a look at a boater's electrics and I must admit I did find his situation to be unusual. The said boater had bought an LED light out of curiosity. Initially, he was going to pay an AC electrician to install LED lights on his boat at a fair cost. I was baffled when I heard the AC electrician had communicated to the boater that he needed a transformer. I assumed the idea was to connect the LED's to the boats AC supply via a transformer which seemed to me at the time a bit of a bad idea when there is already a 12 volt system and batteries on board.

Anyway, the boater took my advice and just put the LED light in his 12 volt supply and, at first, he was more than happy. However, at night something strange happened. The said LED light was glowing quite brightly till the boater switched on his fluorescent low watt lights. At that point the LED dimmed to the point of zero light. Indeed, it would shine quite well always till other non LED lights were activated at which point it would again fade.

My suggestion was it had to be voltage drop as battery charge was a bit low. However, the boater did raise a good point that any voltage drop was only effecting the LED. Weirdly, if he turned his engine on and the alternator kicked in, the LED light, plus all other lights shone brightly.

The only thing I could suggest was that maybe the LED light is more vulnerable to voltage drop than his other lights? I know also if you have a chain of lights in series, voltage will drop as current flows from lamp to lamp (likewise there is drop along long cable runs). Given the LED was downstream from the battery bank, voltage will have dropped across each lamp by the time current got to the LED.

Weirdly, the boater told me that this didn't happen if he swapped the LED for a regular light. Conclusion seems to be that if your battery is a bit down, normal lights will still work but the LED will die a sudden death!!

Or could it be his LED isn't designed for regular boat service. Instructions on the packet assume a transformer will be used and it seemed to me the LED was intended as a low volt kitchen lights, fed by stepped down A.C.

I was a bit baffled to a point. Anyone who has any theory, feel free to contribute. I did suggest at the time he should just ditch all the regular lights and just put in a chain of LED's. I can say, though, he's not at all impressed by his light.

[Chalky]

Coupled electromagnetic interference probably running through the boats wiring system.

[Tony Brooks]

12V fluorescents have an inverter type thingy in them to drive the tube and I know from problems with car radios these can and do create interference. Sometimes on the supply. I wonder if the interference (ripples) on the supply was upsetting the electronics in the LEDs, but if they were "mains" ones for us ewith a transformer then maybe there are no electronics in them.

 

Could such interference cause overheating in the LEDs?

12V fluorescents have an inverter type thingy in them to drive the tube and I know from problems with car radios these can and do create interference. Sometimes on the supply. I wonder if the interference (ripples) on the supply was upsetting the electronics in the LEDs, but if they were "mains" ones for us ewith a transformer then maybe there are no electronics in them.

 

Could such interference cause overheating in the LEDs?

 

Chalky beat me to it.

[FORTUNATA]

12V fluorescents have an inverter type thingy in them to drive the tube and I know from problems with car radios these can and do create interference. Sometimes on the supply. I wonder if the interference (ripples) on the supply was upsetting the electronics in the LEDs, but if they were "mains" ones for us ewith a transformer then maybe there are no electronics in them.

 

Could such interference cause overheating in the LEDs?

 

Chalky beat me to it.

To be honest, it was an amusing day spent on his boat looking at the LED and explaining matter-of-factly how voltage drop works. However, he burst my technological faith bubble when he asked me why the "blasted" LED alone was dimming. True enough if he swapped his LED for any regular bulb, all the bulbs performed well even under non ideal battery charge conditions.

 

In the end, all I could suggest was this: Somehow his LED was more prone to voltage drop than the other lamps. But how and why?

 

Here is some information to help:

 

His LED seems to have been sold as a light you would fit in a house. It has a transformer supplied and the instructions read you should connect the transformer to mains and then the DC output to the LED. We debated this at length. I said I could see no reason at all why the LED couldn't be just wired direct to the DC supply and bypass the need for the transformer. This was difficult for me at the time as an AC licensed sparky had told the guy he MUST use the transformer to which I could only respond in his case he already had 12 volts DC supply on his boat so why connect the LED to boat hook-up AC and then step it down to DC? Why not just connect the LED to the batteries?

 

Here is the odd phenomenon I spotted. The boater agreed to start his engine as it seems the LED runs fine once charge is going to the battery. As he switched on his relay, suddenly I saw the LED lamp in the boat burst into life. Then he came back, switched on a tube light adjacent and the LED went out (very very dim). Had he started the engine, though, all would have been well - LED and all other lights would be bright.

 

I did suggest that just maybe his LED light wasn't the best. Could it be the resistor in it a hidden wattage factor? I have a 1990's book that informed me LED's have a resistor that steps down voltage so could the overall wattage of his LED be a lot higher than assumed? I was guessing at this point.

 

The major drama of the day erupted when I suggested he should remove all his regular lights and then install LED's right down the line from battery bank to final light. He then asked me why he should remove all his good lights to then replace them all with "crummy LED's".

 

Basically this guy isn't at all impressed. Some of it I confess strikes me as odd. I've never encountered this before.

 

 

 

[Chalky]

The LED will contain a switching power supply. So does the fluorescent lamp. The electrical noise from one is causing the problem and either causing the power supply to stop or causing it to beat / hetrodyne. Fixes

 

• Make sure the LEDS and fluorescent lamps have separate earths and power feeds only joining at the fuse box.
• Increase the size of the earth to the Fluorescent. Ideally you want braid not wire - its about surface area not current - you need a good radio frequency earth.
• Move the circuits for the LEDS and fluorescent lamps as far away from each other as possible.
• Update the fluorescent lamps to more modern ones.

Other fixes involve circuit changes to the lights but require a good level of electronics skill and appropriate test equipment.

I've never encountered this before.

 

We see this kind of thing a lot during vehicle development which is why automotive parts are engineered to a high standard to avoid this. It's caused by one of those transients that some people say don't exist...

[bottle]

Chalky and Tony have lost me, not difficult I may add.

 

Simplest solution, dump the LED and put back original

 

or

 

Dump all fluorescents and replace with LED's suitable for a boat.

 

Domestic (house) ones supplied by a transformer are not designed for boat use where voltages can vary.

[Phil Ambrose]

I have a mix of LED lights and 2D fluro lightd (gradually switching to LED) I have never seen dimming as described but I did use Bedazzled LED bulbs and judging by the electronics on the back of the lamp PCB there is a lot involved. Possibly LEDs intended for domestic use on 240v differ to ones as supplied by Bedazzled.

Phil

[Chalky]

 

Domestic (house) ones supplied by a transformer are not designed for boat use where voltages can vary.

 

It's not a voltage issue - it's electrical noise from one unit upsetting another. The electrical noise is travelling along the wires. By separating the circuits you reduce the change of the noise from one going into the other. By adding a good earth you can help reduce the noise at source.

[Nickhlx]

I would say none of the above is the case...

 

Straight LEDs need to be driven by constant current - If you connect a single white ( other colours turn on at different voltages) LED to a variable voltage PSU, duly current limited to the devices ratings, then slowly crank the voltage up from zero, nothing will happen until about 3.0 volts when the device starts to conduct. It will go from "beginning to glow" to full brightness over a narrow voltage range of maybe 2.7 to 3.0 volts.

 

Put five of these in series, and this range becomes approximately 13.5 to 15.0, and (for this example) it will only operate on a well charged or on charge battery.

 

The actual range is device specific. i.e. it could be 2.4 to 3.5 or even wider, and my guess is his is right in the range to give the effect he is seeing.

 

The solutions ? Either feed them from a module (that gives the LED string a constant current) over an input supply voltage from around 10 volts to 15 volts ( for nominal 12 volt boats). These modules are available via E-Bay for less than £10, and possibly less than £5... or replace the LEDs with ones with a built in PSU that enables them to work from e.g. 10-28 volts...

 

Nick

Edited September 15, 2014 by Nickhlx

[rjasmith]

I'm afraid I completely agree with what Chalky has said although my experience goes back to the mid 70's in CEGB (now Nat Grid) when we had to learn this stuff the hard way!

 

The immunity to various RF interference effects varies greatly amongst cheaper/older devices and also when introducing things designed to operate in a household environment into the vastly harsher electrical environment of a car or a boat.

 

There are complex standards that should be applied to avoid this for products intended to go in cars, there are more general EU directives that should keep designers aware/complying with electromagnetic interference immunity/emission but who knows what Far Eastern suppliers of the cheaper LED actually do when they manufacture their LED driver circuits!

 

Richard

Edited September 15, 2014 by rjasmith

[Phil Ambrose]

A good argument for using admittedly more expensive LEDs from Bedazzled which have a range of 10v to 30v. I am happier spending more for a superior product,

Phil

[rogeriko]

Nickhlx has it right the led he has needs about 13v to run when you turn on other lights the battery drops to 12.4 or so and the led cuts out. You must use 12v car leds and you wont have this problem. They work from 10v to 15v.

 

80 pence each

 

http://www.ebay.co.uk/itm/10Pcs-Day-White-24LED-5050-SMD-Dome-Door-Light-Panel-Bulb-T10-Adapter-12V-/111246602512?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item19e6d07110

[by'eck]

 

It's not a voltage issue - it's electrical noise from one unit upsetting another. The electrical noise is travelling along the wires. By separating the circuits you reduce the change of the noise from one going into the other. By adding a good earth you can help reduce the noise at source.

 

 

12V fluorescents have an inverter type thingy in them to drive the tube and I know from problems with car radios these can and do create interference. Sometimes on the supply. I wonder if the interference (ripples) on the supply was upsetting the electronics in the LEDs, but if they were "mains" ones for us ewith a transformer then maybe there are no electronics in them.

 

Could such interference cause overheating in the LEDs

 

Read the OP again carefully: Indeed, it would shine quite well always till other non LED lights were activated at which point it would again fade.

 

i.e. not necessarily fluorescent

 

IMHO this adds weight to Nickhix's suggestion that its a narrow voltage range issue from an unsuitable LED.

[Nickhlx]

If it helps, I will happily test one of these LEDs and plot a graph of voltage against current drawn (brightness), and I am quite certain that there will be a sharp "knee" in the plot at around 12.0 to 12.5 volts... Of course, during the evening if the engine is off and the system running items around the boat, the battery voltage will be no more than about 12.7 volts and that at the beginning of the evening. With voltage being dropped around the system, and especially if the halogen lights are run part of the way along the same cables, or if the same breaker is supplying other lights, the voltage drop at the (LED) light will be fluctuating maybe 0.5 Volts, which will barely be visible on a halogen's brightness, but could (will) be putting the LED each side of its acceptable working voltage.

 

What also interests me is what would limit the current / power being drawn, (nothing) if the LED is being powered from a variable boat supply ? ( our Beta 43 / Iskra 175 is at 14.8 volts when on charge with the engine running ! )

 

OP - Can you discover the part number of the LED light in question ?

 

I wonder whether, as the device is not being used with its intended (either regulated voltage, or hopefully, constant current) power supply, (or that "transformer" that has this control circuitry built in), it will die early in its expected life....

 

Technically, a "transformer" is an a.c. device which translates fluctuating voltages... The "transformer" that this LED was originally intended to be used with is likely much more than that and will be supplying the necessary

constant current drive that the LED needs - you can (easily) do this all without mains though, with the aforementioned modules off E-Bay, and would be my preferred method

 

Nick

Edited September 16, 2014 by Nickhlx

[Chalky]

When I build LED lights for the boat I'm careful to design the power converter to run at a minimum of 10V to avoid this problem. On our boat we get nowhere near this. If there is enough of a volt drop on the wiring to cause it to drop out then another fix might be to upgrade the wiring to reduce the volt drop. Alternatively the batteries could be on the way out. I must admit I've always used automotive grade parts on the boat (since I work with them) not domestic since they're not engineered to the same standards.

[junior]

A good argument for using admittedly more expensive LEDs from Bedazzled which have a range of 10v to 30v. I am happier spending more for a superior product,

Phil

When I replaced all the bulbs in my boat for LED I bought a mixture of Bedazzled bulbs and some cheapies off eBay. The bedazzled ones cost in the region of £9 each. The eBay ones cost about £9 for 4 bulbs. 12 months on I have no ideas which ones were which and they all work exactly the same and as well as each other.

[Phil Ambrose]

When I replaced all the bulbs in my boat for LED I bought a mixture of Bedazzled bulbs and some cheapies off eBay. The bedazzled ones cost in the region of £9 each. The eBay ones cost about £9 for 4 bulbs. 12 months on I have no ideas which ones were which and they all work exactly the same and as well as each other.

I can well believe that but you are not running them with any fluros are you? The problem of dimming appears to manifest itself when using LEDs together with Fluros

Phil

[1st ade]

"Domestic" LED's (as others have commented) are designed to run off 12v +/- not much. The "Transformer" will actually contain a transformer (240 --> 12), a rectifier (AC --> DC) and some sort of regulator. The ones that allow dimming either 'chop' the power (50% means the LED is on at full power for half the time) or are very clever at sensing the current. Car / Marine 12v LED's have an internal regulator so accept 10-15v or so. The difference is pennies but when you are selling sets of eight or ten at B&Q...

 

In the reverse direction, I once blew up a quite expensive (domestic) central heating controller on a friends boat. I spotted that it ran off 12v internally so removed the transformer / regulator etc and just let the relay switch 12v to the circulating pump. Job done I thought, now he doesn't have to run the inverter just to have central heating.

 

All was well until the battery voltage destroyed the CH controller when he went onto shore power...

[bottle]

 

It's not a voltage issue - it's electrical noise from one unit upsetting another. The electrical noise is travelling along the wires. By separating the circuits you reduce the change of the noise from one going into the other. By adding a good earth you can help reduce the noise at source.

 

I realise that but the bit you quoted stands.

[FORTUNATA]

I can well believe that but you are not running them with any fluros are you? The problem of dimming appears to manifest itself when using LEDs together with Fluros

Phil

I'll pass the information onto him. To be honest, I'm not really too clued up on LED lights except the early ones were run on 2 volts so would lose 10 volts dropped by a resistor wired in series. This may have changed in modern LED lights. I don't know what make of LED he used but it came with a transformer and he was using 12 volt halogen lights elsewhere (tubes).

Unsure at this point as to how HF could cancel out a DC LED light but will pass the information on.

My advice to him at the time was to add another house battery and change all, of his lights to LED. I've seen some at Aldi that were spot lights and reasonably priced. I think he got the ones he now has from a big DIY chain.

[Tony Brooks]

I'll pass the information onto him. To be honest, I'm not really too clued up on LED lights except the early ones were run on 2 volts so would lose 10 volts dropped by a resistor wired in series. This may have changed in modern LED lights. I don't know what make of LED he used but it came with a transformer and he was using 12 volt halogen lights elsewhere (tubes).

Unsure at this point as to how HF could cancel out a DC LED light but will pass the information on.

My advice to him at the time was to add another house battery and change all, of his lights to LED. I've seen some at Aldi that were spot lights and reasonably priced. I think he got the ones he now has from a big DIY chain.

 

 

Not you - him!

[raymondh]

I have a mix of cheap ebay LEDs and as fitted flo tube fittings in my motorhome all work no probs and as all LED lamps are made in China/Far East I always buy from ebay and have 20 in the boat all working fine

I always purchase more than I need so have lots of spares!! as at the price I pay I did expect some failures, but still waiting

See an example

http://www.ebay.co.uk/itm/Home-Car-2W-G4-DC10-30V-LED-Light-Lamp-Garden-Camper-Bright-SMD-Indoor-Bulbs-/261595587138?pt=UK_Light_Bulbs&hash=item3ce84fe242

99p each delivered - yes its an auction but these are only £1.35

 

http://www.ebay.co.uk/itm/High-Power-G4-AC12V-DC10-30V-15-SMD-5730-LED-Light-Soptlight-Warm-Pure-White-/200995763882?pt=UK_Light_Bulbs&var=&hash=item2ecc47f6aa

 

Ray

[Rambling]

one of my cheap ebay LEDs just let off a load of smoke and the whole circuit died. Bit concerned that it could have caused a fire. I will certainly not be using cheap ebay bulbs again.

Edited October 21, 2014 by Rambling