What's causing flickering 12v light?

[Frugal]

Hi.
May I suggest the move to LED's gives you far better choice and almost eliminates any radio interference as a bonus.
I have used flexible strips which are obtainable in 5 meter by 300 led's.
They are cuttable down to 3 leds and can be waterproof with a choice of colour, warm white or cool white. Usually with an adhesive back. All 12 volt and correct polarity required.
Try Ebay or Alibaba.
Cheers

[GordMay]

Greetings and welcome aboard the CF, Frugal.

[rwidman]

Before we all run out and buy cheap LED fixtures or strips off eBay, there's an important consideration:

LEDs by themselves are very sensitive to the amount of current flowing through them. Not enough, not much light. Too much and they burn out, often instantly. The cheap way of controlling the current is with a dropping resistor in series with each LED (or group of LEDS). The problems with dropping resistors are, it's inefficient because much of the power is turned to heat by the resistor, not light by the LED and more importantly, the resistor must be calculated based on the applied voltage and in boats (and vehicles) that voltage is not constant. It could be 12 volts or less with a weal battery and it could be close to 15 volts when the alternator or charger is charging the battery. Calculate the resistor for 15 volts and the light will be dim when there's no charging going on. Calculate the resistor for 12 volts and the LEDs will a much shorter life than expected or even fail as soon as charging starts.

The solution is to include a constant current driver in the fixture or bulb. This constant current driver regulates the current flowing through the LEDs to a safe value. It is also more expensive than a dropping resistor.

So how do you know the difference? If the specs say something like 9 volts to 28 volts, you have a constant current driver and can expect the LEDs to last their expected 20,000 hours. If the specs say 12 volts, they may be fine at first but they will begin to fail quickly as you use your boat.

You pays your money and you takes your choice.

[colemj]

With that said (and theoretically true), we haven't experienced this in practice with the cheap LED strip lights that come in a 16' roll. They only use resistors for current regulating for every bulb. They do heat up a small amount with waste current, but still only use ~2A when all 300 LED's are operating (at which level they could light up a cathedral). We have put strip pieces of these in many places on our boat and have not had any fail in the past 4 years. Additionally, they do not dim or brighten over the discharging/charging range on our batteries. Neither do our resistor-controlled LED bulbs in our fixed light sockets.

These LED strip lights cost <$1/foot (one foot contains about 18-20 individual LED's), so if they do ever go bad, I will just cut off another strip and stick it back on.

Mark

[newhaul]

The cheap ones I linked to are designed from ground up for RV and marine use they don't get hot and they produce plenty of light one single side fixture produces the same lumens as a 75 watt light bulb and only draw 5 watts so you can see the significant savings in power and at ten buchs a pop that's not much more than thecost of an incandescent 12 volt 75 watt bulb and heck if it only lasts 500 hrs of use which is about what you get out of an incandescent bulb I figure I'm way ahead considering the power draw difference and to a sailboat power is a very precious commodity that costs $$$ to make and at an expected 20000 hrs that would pay for its self many times over in fewer bulb changes alone

[rwidman]

Originally Posted by colemj

With that said (and theoretically true), we haven't experienced this in practice .......

I did. I installed some cheap eBay lights and the individual LEDs failed one by one until they weren't bright enough to read by. Yeah, I might have gotten 50 hours or so.

Sometimes it's cheaper to pay more for a better product.

[Gone2long]

Originally Posted by Stu Jackson

The referenced "starter" in the fixture is called a ballast. Learn how fluorescent lamps work (Google "How things work" or wikipedia) and go from there.

Will do,

Thanks,

G2L

[rwidman]

Originally Posted by Gone2long

Will do,

Thanks,

G2L

Read post #7

[Gone2long]

Originally Posted by Gone2long

Got a 12 volt, 5 watt, flourescent light on board that keeps flickering whenever I turn it on. It will flicker and sometimes go on, sometimes not. Once on, the bulb will stay lit.


If I put a new bulb in, I get a similar problem, so it seems that the problem is in the connection to the bulb.

Where/how exactly should I look for the problem?

All advice greatly appreciated.

G2L

I have attached a photo of the light and related parts. Last night the bulb flickered and went on. It worked fine for a few hours, then simply went off.


I closed the switch, then opened it today to trouble shoot the problem, and when I flicked the switch, wires started smoldering and all metal parts got super hot. I turned the unit off, disconnected it and pulled all parts out.


I figure that either the starter or the switch shorted out. Both were hot as heck. Take a look and tell me if anyone knows what exactly went wrong, and how to fix it. You can get a good close look at the parts and wiring diagram by clicking on the photos

Note that the unit is rated at 24 volts and the bulb is actually 8 volts, not 5.

thanks folks,

G2L

[PDA1]

The starter shorted out.

Get rid of it forever- truly you're now "playing with fire".

Put in an LED.

Florescent bulbs were a transition technology between incandescent and LED.

I've often wondered how many people have been injured or died as a result of florescent lights. Particularly in houses when you turn the light on and the florescent takes its good old time to become brighter.

[ur2slo]

Originally Posted by Gone2long

I figure that either the starter or the switch shorted out. Both were hot as heck. Take a look and tell me if anyone knows what exactly went wrong, and how to fix it. You can get a good close look at the parts and wiring diagram by clicking on the photos

Note that the unit is rated at 24 volts and the bulb is actually 8 volts, not 5.

G2L

Hi All,
Curious on this one, I have a wee bit of electric knowledge, just about enough to be dangerous........

One thing in your pic caught my eye. Your switch ratings. I came across this problem before and it may help in your situation.

Your design ratings on the switch are AC voltage Volt/Amp limited.

Switches designed for "Alternating Current Voltage" have typically a smaller contact area and tension on the internal contacts versus "Direct Current Voltage" rated switches. The voltage phase shift that occurs every 60 cycles requires less contact area, while DC due to it's continuous amperage on the contacts have larger contact area and consequently more "ampacity" of the switch.

I dont like to see any heat on a boat's electrical system, it screams "HELP"

Might be more complicated, but that very issues gave me alot of headaches years ago....

FWIW.....(correct as required)



Of course, you could go buy a new unit and have less headaches.....and safer.

I keep seeing more ...... The starter is rated at 24vdc, I suspect you are inputting 12v, correct?

Ohms law states that E=I*R, so consequently when the voltage drops, the amperage INCREASES, hence your heat generated by trying to push 12v thru a 24v hole to put it simply, the amps produce heat instead of work.

[Dauntlessny]

Originally Posted by colemj

Alternately, keep the fixture and wire in a couple of passes of flexible strip LED lights. I have seen several of these done when the fluorescent lights went bad and they worked out remarkably well. Better than the original, IMO.

Mark

That's what I did and they work wonderfully.

Also, I got them on Amazon, so very inexpensive.
Just make sure they are 12volt as I am now noticing a lot of LEDs are all sorts of voltages, from 12 to 36v.

There is enough 12v stuff out there, do not screw around with anything that needs a transformer or ballast.

[GordMay]

Originally Posted by Stu Jackson

The referenced "starter" in the fixture is called a ballast. Learn how fluorescent lamps work (Google "How things work" or wikipedia) and go from there.

Originally Posted by rwidman

Well, there are starters and there are ballasts. A starter is a metal canister about the diameter of a nickel and an inch long that's visible from the outside of the fixture and can be replaced by turning it to the left about an eighth of a turn. Starters in florescent fixtures are pretty rare these days. Most lamps are self starting...

There are several types of fluorescent lamps & ballasts: including preheat, rapid start, instant start, and programmed start.
Preheat ballasts require a separate “starter” to preheat or maintain the temperature of the lamp electrodes, prior to the ballast providing a (500 - 600V) starting/arcing voltage.

[Gone2long]

Originally Posted by rwidman

Before we all run out and buy cheap LED fixtures or strips off eBay, there's an important consideration:

LEDs by themselves are very sensitive to the amount of current flowing through them. Not enough, not much light. Too much and they burn out, often instantly. The cheap way of controlling the current is with a dropping resistor in series with each LED (or group of LEDS). The problems with dropping resistors are, it's inefficient because much of the power is turned to heat by the resistor, not light by the LED and more importantly, the resistor must be calculated based on the applied voltage and in boats (and vehicles) that voltage is not constant. It could be 12 volts or less with a weal battery and it could be close to 15 volts when the alternator or charger is charging the battery. Calculate the resistor for 15 volts and the light will be dim when there's no charging going on. Calculate the resistor for 12 volts and the LEDs will a much shorter life than expected or even fail as soon as charging starts.

The solution is to include a constant current driver in the fixture or bulb. This constant current driver regulates the current flowing through the LEDs to a safe value. It is also more expensive than a dropping resistor.

So how do you know the difference? If the specs say something like 9 volts to 28 volts, you have a constant current driver and can expect the LEDs to last their expected 20,000 hours. If the specs say 12 volts, they may be fine at first but they will begin to fail quickly as you use your boat.

You pays your money and you takes your choice.

Thanks for the details. See the responses and my answers below.

G2L

[Gone2long]

Originally Posted by ur2slo

Hi All,
Curious on this one, I have a wee bit of electric knowledge, just about enough to be dangerous........

One thing in your pic caught my eye. Your switch ratings. I came across this problem before and it may help in your situation.

Your design ratings on the switch are AC voltage Volt/Amp limited.

Switches designed for "Alternating Current Voltage" have typically a smaller contact area and tension on the internal contacts versus "Direct Current Voltage" rated switches. The voltage phase shift that occurs every 60 cycles requires less contact area, while DC due to it's continuous amperage on the contacts have larger contact area and consequently more "ampacity" of the switch.

I dont like to see any heat on a boat's electrical system, it screams "HELP"

Might be more complicated, but that very issues gave me alot of headaches years ago....

FWIW.....(correct as required)



Of course, you could go buy a new unit and have less headaches.....and safer.

I keep seeing more ...... The starter is rated at 24vdc, I suspect you are inputting 12v, correct?

Ohms law states that E=I*R, so consequently when the voltage drops, the amperage INCREASES, hence your heat generated by trying to push 12v thru a 24v hole to put it simply, the amps produce heat instead of work.

Yes, it seems that you may have isolated the problem. Truly an education for me.

To solve the problem, I bought a 5 watt, 12 volt LED bulb, but I could not find a DC mounting fixture for it, so I bought a 240 volt fixture to screw the bulb into. I have not bought a new switch, since I could not find one designed specifically for a 12 volt system.

Now, using your logic, by screwing my 12 volt LED light into the new 240v fixture, am I causing the same, over-heating problem that I had w. the fluorescent fixture on a DC switch? Or, as Ron suggests above, may I simply be limiting the life or efficiency of my new LED bulb?

All comments truly appreciated.

G2L