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Old 06-04-2014, 07:41   #1
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LED Polarity

I have installed LED steaming light but it doesn't work. We checked before I stepped the mast. I understand that polarity is important to LEDs. If I merely reverse the wires on the deck, would it solve the problem - if polarity is the problem. What would be the risks?

Electricity, especially direct, is most baffling to me.
Phil
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Old 06-04-2014, 07:45   #2
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Re: LED polarity

Phil,

Check with the light supplier. Many lights will not be damaged by reversal but some may be. If the light supplier used polarity protection then it will be ok to switch the polarity.
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Old 06-04-2014, 11:31   #3
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Re: LED polarity

Reverse the polarity. Polarity protection is easy and cheap so I can't imagine an LED running light designed without it. If it still doesn't work most likely a pulled or pinched wire when the mast was stepped. You did check that there is power where the wires connect?
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Old 08-04-2014, 19:12   #4
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Re: LED polarity

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Reverse the polarity. Polarity protection is easy and cheap so I can't imagine an LED running light designed without it. If it still doesn't work most likely a pulled or pinched wire when the mast was stepped. You did check that there is power where the wires connect?
The sort of LED (or LED fixture with integral regulation) that's meant for marine applications should be able to survive reversed 12v.
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Old 08-04-2014, 19:20   #5
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Re: LED polarity

Light-emitting diode (LED)...diode means current will flow in only one direction through the device.

If the light is not ON the possible causes are:

- the LED is defective
- the LED is not getting the proper voltage (open wire or high resistance connection or voltage too low)
- the voltage polarity is reverse of that needed to flow through the diode(s)

If the polarity is reversed the diode will not be damaged (unless the voltage applied is high enough to cause a breakdown of the diode...much higher than your 12V supply).
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Old 09-04-2014, 04:11   #6
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Re: LED polarity

Most leds have an absolute max reverse breakdown voltage of about 5v by the way

Dave
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Old 09-04-2014, 04:29   #7
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Re: LED polarity

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Light-emitting diode (LED)...diode means current will flow in only one direction through the device. .....
'best statement yet on this thread here by fryewe.
You did not mention the type of socket on the bulb. If it's a double bayonet; then just reverse to bulb or the wires. I'd just turn the bulb 180 degrees.
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Old 09-04-2014, 05:00   #8
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Re: LED polarity

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'best statement yet on this thread here by fryewe.
You did not mention the type of socket on the bulb. If it's a double bayonet; then just reverse to bulb or the wires. I'd just turn the bulb 180 degrees.
Capn' F's method has flaws rooted in laziness and efficiency...

There is nothing wrong with cutting two connectors, re-stripping, connecting, and sealing...

Your choice... You can do it the easy way... Or do it like the rest of us...
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Old 09-04-2014, 08:27   #9
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Re: LED Polarity

Lots of misinformation here. Many double bayonet connectors are keyed so the bulb can only go one way. Also, most LED lights use a current regulated power supply. It's not just an LED in there. The most energy efficient reverse polarity protection is a diode across the DC input. But it will trip a breaker if polarity is reversed. Another type is a diode bridge at the input but this has about 1V drop and thus wastes some power. Because of these factors not all LED lights have polarity protection but most do.
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Old 10-04-2014, 21:39   #10
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Re: LED Polarity

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...Because of these factors not all LED lights have polarity protection but most do.
I expect (hope) that all LED bulb/assembly/fixtures intended for boat nav lights bloody well better be able to withstand a reverse voltage of at least 12v, because over their lifetime they will likely be exposed to many times 12v from static due to mishandling, mast raising/lowering, accidental reversal, and induced voltages from atmospheric phenomena. I believe some of the first crop of LED marine lights had embarrassingly short lives because the makers skimped on such protection.
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Old 10-04-2014, 21:56   #11
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Re: LED Polarity

The better LED bulbs are actually not polarized which is really sweet. I always try to make sure the max. bulb voltage is 25-30V. I've found that a 15V max voltage is not quite high enough, least wise for my first anchor light which used a DR. Led blub.

YEs go ahead and reverse the wires. If the bulb does not light then you have other problems.
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Old 11-04-2014, 04:38   #12
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Re: LED Polarity

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The better LED bulbs are actually not polarized which is really sweet. I always try to make sure the max. bulb voltage is 25-30V. I've found that a 15V max voltage is not quite high enough, least wise for my first anchor light which used a DR. Led blub.

YEs go ahead and reverse the wires. If the bulb does not light then you have other problems.
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