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Old 20-12-2016, 13:00   #31
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Re: Wiring compass light to two separate circuits

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You are bringing up red herring false problems.
I disagree, these are potential issues that should be considered.

Quote:
The 'bleed of current' as you call it, is much less than wiring the compass light in parallel with the nav lights. Something like a few microamps in a circuit which was designed for 5 amps. Truly negligible.
The navigation lights could have been wired poorly, and there may be high contact resistance in the deck fitting and light fixture(s). (Something I see all the time.) The current consumed by the compass light circuit (which we currently don't know) could be enough to be an issue.

Quote:
Depending on whether you have dead batteries or are running the engine, the supply voltage will range from 11 volts to 14 volts.
Correct, or even more variation. I'm not going to bother checking but I am pretty sure regulations for minimum running light brightness would specify the energy supply conditions for that specification.

Quote:
If you lose 0.6 volts in the diode, that leaves you with 10.4 to 13.4 volts to drive the compass led which can take a maximum of 2v.
We don't know if the compass light is incandescent or LED.

We certainly don't know what the energy requirements for what brightness, and the minimum acceptable brightness to the user are.

There is also the wiring losses for both circuits to consider.

The other very real possibility, is that a short circuit in the compass light, could blow the breaker that also powers the running lights, unless compass light circuit over-current protection is included (as near the running light circuit tap as possible).

The devil (red herring, or whatever one wishes to call it) is always in the details. ;-)
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Old 20-12-2016, 14:48   #32
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Re: Wiring compass light to two separate circuits

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Originally Posted by ramblinrod View Post
I disagree, these are potential issues that should be considered.



The navigation lights could have been wired poorly, and there may be high contact resistance in the deck fitting and light fixture(s). (Something I see all the time.) The current consumed by the compass light circuit (which we currently don't know) could be enough to be an issue.



Correct, or even more variation. I'm not going to bother checking but I am pretty sure regulations for minimum running light brightness would specify the energy supply conditions for that specification.



We don't know if the compass light is incandescent or LED.

We certainly don't know what the energy requirements for what brightness, and the minimum acceptable brightness to the user are.

There is also the wiring losses for both circuits to consider.

The other very real possibility, is that a short circuit in the compass light, could blow the breaker that also powers the running lights, unless compass light circuit over-current protection is included (as near the running light circuit tap as possible).

The devil (red herring, or whatever one wishes to call it) is always in the details. ;-)
I'm not sure I follow you? It seems to me if someone does not have brains enough to flip a switch as to which running lights they want on or the compass light, maybe they should stay ashore. Buy a car they will almost drive themselves. The least complicated you can keep a boat the better, a dealer in just not around the corner.
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Old 20-12-2016, 15:51   #33
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Re: Wiring compass light to two separate circuits

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Originally Posted by Cadence View Post
I'm not sure I follow you? It seems to me if someone does not have brains enough to flip a switch as to which running lights they want on or the compass light, maybe they should stay ashore. Buy a car they will almost drive themselves. The least complicated you can keep a boat the better, a dealer in just not around the corner.
Another poster posted that he didn't understand why we would consider alternatives to branching the compass light off the running light and tricolour light circuits, with blocking diodes.

I gave some reasons.

The best solution in my opinion is that the compass light be operated by its own switch and breaker.

That being said I don't want to run another cable up the mast, so the plan is to use reversing polarity on the anchor light cable, so one polarity runs the anchor LED and the other the trilight LED, as I will never want both on at the same time. So all I need is a DPDT switch and Bob's your uncle.
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Old 20-12-2016, 17:29   #34
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Re: Wiring compass light to two separate circuits

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Originally Posted by ramblinrod View Post
Another poster posted that he didn't understand why we would consider alternatives to branching the compass light off the running light and tricolour light circuits, with blocking diodes.

I gave some reasons.

The best solution in my opinion is that the compass light be operated by its own switch and breaker.

That being said I don't want to run another cable up the mast, so the plan is to use reversing polarity on the anchor light cable, so one polarity runs the anchor LED and the other the trilight LED, as I will never want both on at the same time. So all I need is a DPDT switch and Bob's your uncle.
I should add, that my compass light is connected to my running lights.
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