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Author Topic:   Nav lights heating up ??

davemor posted 06-15-2003 04:14 PM ET (US)
When ever my Nav lights are on they get very very hot to the touch, this dosen't seem normal to me. Does any one know what it might be ?? The whole metal housing gets too hot the the touch. Thanks Dave
jimh posted 06-15-2003 05:37 PM ET (US)
I think it is normal for the navigation lamp fixture to have its temperature rise above ambient, but how much above ambient should it be?
Excessive temperature rise could be caused by the lamp in the fixture generating too much heat. Often in devices like this there are a number of lamps which will fit in the fixture's socket. Each of these various different lamps will produce different amounts of light output, normally in proportion to the amount of current flowing through them. That current is in proportion of the voltage applied to them.
The maker of the navigation light fixture probably chose a lamp that would provide the proper amount of light specified in the regulations. Or at least one would hope they did. The range of the light's visibility for a legal navigation light varies with the size of the boat.
In many outboard boats the voltage available to the navigation lighting circuit is unregulated and is just the raw battery voltage subject to variation from the charging circuit of the engine. It is not unusual to see voltages as high as 15-16 volts.
The lamp is rated to perform at 12-volts, so when confronted wtih 16 volts is draws much more current, and it produces more heat.
I would recommend that you check the navigation light fixtures and confirm that you have the proper lamps in them.
Then I recommend you check the voltage being applied to them. If the voltage is too high, you might consider replacing the lamps with another style. It is not unusual for the lamps to be rated in small increments.
We used to always use lamps rated at 28-volts in circuit which operated the lamps at 24-volts. This gave much longer lamp life and reduced the temperature of backlit indictors which were part of switch fixtures that had to be pushed to operate.
Because of the requirement that the navigation light fixture produce a certain amount of visible light, you may not have such a free hand in chosing a lamp that runs at a higher voltage.
You ought to identify the maker of the navigation lights and check with them about the proper lamp to be used.
Jerry Townsend posted 06-15-2003 09:21 PM ET (US)
Another possibility is a poor electrical connection within the lamp housing - either at the lamp/socket or a poor connection of one of the leads. The reason for this is that a poor electrical connection increases the resistance and the flow of electricity through that resistance generates heat. ---- Jerry/Idaho
jimh posted 06-16-2003 12:46 AM ET (US)
Jerry, according to Ohm's law the power in a circuit varies in inverse proportion to the resistance. Any resistance increse due to poor connections would reduce the total power consumed by the circuit.
In the case of the bulb most of the electrical power it consumes is converted into heat and only a tiny portion into light energy.
I would tend to think that any increased resistance in the circuit would have the affect of reducing the total current consumed and thus reducing the amount of heat produced.
I should also mention that my analysis is a little simplistic because of the nature of incandescent lamp filaments. They often act as negative resistances, that is to say the resistance they present varies depending on the amount of current flowing through them. The resistance tends to increase as current increases. The cold filament often has a lower resistance than the warm filament. This could effect the heating, but I don't think it would have enough effect to cause the total heat output to increase with decreasing current flow.
davemor posted 06-16-2003 02:54 AM ET (US)
Thanks for the input, Tomorrow i will check the volts going to the socket. And also check the size of the lamp. The two bow lights , plus including the stern light gets hot. Could it be all the lamps are wrong. I will check tomorrow and let you know. Thanks Dave
where2 posted 06-16-2003 12:43 PM ET (US)
I find it common that my single combination Perko red-green gets hotter than comfortable to touch. However, given the nature of running an incandesent bulb in a small enclosed fixture, it is what I would expect. I continue to wait for the day when Perko makes a direct replacement for my combination light as an LED array. My dad has a pair of separate side mount Perko LED lights. Even running off a transistor 9V battery, they are bright!
Jerry Townsend posted 06-16-2003 01:02 PM ET (US)
Jim - with all due respect - Ohm's law states that the voltage drop varies directly as the current and the resistance. Joule's law states that the flow of current through any resistance R dissipates energy as heat and that the electrical power varies as the product of the voltage and current.
Therefore, the electrical power (dissapated as heat) varies as the product of the current squared and the resistance.
Then additional resistance will increase the current draw and also cause the device (connection or component) to heat up.
That was my only point - increased resistance via corrosion, a cold solder joint, et.al. and particularily on the ground would add heat to the lamp housing. ------ Jerry/Idaho
Jay A posted 06-22-2003 12:14 PM ET (US)
Hot lights are normal! The givaway is if they are mounted in a glass lens. If it's a plastic lens,then I would be concerned.
jimh posted 06-22-2003 06:55 PM ET (US)
Jerry--I sent you an email on this.
Also, I think in general you want these navigation lamp fixtures to be well sealed against water entry, so by running hot they are probably indicating that they are fairly air tight and thus well sealed.

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Author	Topic: Nav lights heating up ??
davemor	posted 06-15-2003 04:14 PM ET (US) When ever my Nav lights are on they get very very hot to the touch, this dosen't seem normal to me. Does any one know what it might be ?? The whole metal housing gets too hot the the touch. Thanks Dave
jimh	posted 06-15-2003 05:37 PM ET (US) I think it is normal for the navigation lamp fixture to have its temperature rise above ambient, but how much above ambient should it be? Excessive temperature rise could be caused by the lamp in the fixture generating too much heat. Often in devices like this there are a number of lamps which will fit in the fixture's socket. Each of these various different lamps will produce different amounts of light output, normally in proportion to the amount of current flowing through them. That current is in proportion of the voltage applied to them. The maker of the navigation light fixture probably chose a lamp that would provide the proper amount of light specified in the regulations. Or at least one would hope they did. The range of the light's visibility for a legal navigation light varies with the size of the boat. In many outboard boats the voltage available to the navigation lighting circuit is unregulated and is just the raw battery voltage subject to variation from the charging circuit of the engine. It is not unusual to see voltages as high as 15-16 volts. The lamp is rated to perform at 12-volts, so when confronted wtih 16 volts is draws much more current, and it produces more heat. I would recommend that you check the navigation light fixtures and confirm that you have the proper lamps in them. Then I recommend you check the voltage being applied to them. If the voltage is too high, you might consider replacing the lamps with another style. It is not unusual for the lamps to be rated in small increments. We used to always use lamps rated at 28-volts in circuit which operated the lamps at 24-volts. This gave much longer lamp life and reduced the temperature of backlit indictors which were part of switch fixtures that had to be pushed to operate. Because of the requirement that the navigation light fixture produce a certain amount of visible light, you may not have such a free hand in chosing a lamp that runs at a higher voltage. You ought to identify the maker of the navigation lights and check with them about the proper lamp to be used.
Jerry Townsend	posted 06-15-2003 09:21 PM ET (US) Another possibility is a poor electrical connection within the lamp housing - either at the lamp/socket or a poor connection of one of the leads. The reason for this is that a poor electrical connection increases the resistance and the flow of electricity through that resistance generates heat. ---- Jerry/Idaho
jimh	posted 06-16-2003 12:46 AM ET (US) Jerry, according to Ohm's law the power in a circuit varies in inverse proportion to the resistance. Any resistance increse due to poor connections would reduce the total power consumed by the circuit. In the case of the bulb most of the electrical power it consumes is converted into heat and only a tiny portion into light energy. I would tend to think that any increased resistance in the circuit would have the affect of reducing the total current consumed and thus reducing the amount of heat produced. I should also mention that my analysis is a little simplistic because of the nature of incandescent lamp filaments. They often act as negative resistances, that is to say the resistance they present varies depending on the amount of current flowing through them. The resistance tends to increase as current increases. The cold filament often has a lower resistance than the warm filament. This could effect the heating, but I don't think it would have enough effect to cause the total heat output to increase with decreasing current flow.
davemor	posted 06-16-2003 02:54 AM ET (US) Thanks for the input, Tomorrow i will check the volts going to the socket. And also check the size of the lamp. The two bow lights , plus including the stern light gets hot. Could it be all the lamps are wrong. I will check tomorrow and let you know. Thanks Dave
where2	posted 06-16-2003 12:43 PM ET (US) I find it common that my single combination Perko red-green gets hotter than comfortable to touch. However, given the nature of running an incandesent bulb in a small enclosed fixture, it is what I would expect. I continue to wait for the day when Perko makes a direct replacement for my combination light as an LED array. My dad has a pair of separate side mount Perko LED lights. Even running off a transistor 9V battery, they are bright!
Jerry Townsend	posted 06-16-2003 01:02 PM ET (US) Jim - with all due respect - Ohm's law states that the voltage drop varies directly as the current and the resistance. Joule's law states that the flow of current through any resistance R dissipates energy as heat and that the electrical power varies as the product of the voltage and current. Therefore, the electrical power (dissapated as heat) varies as the product of the current squared and the resistance. Then additional resistance will increase the current draw and also cause the device (connection or component) to heat up. That was my only point - increased resistance via corrosion, a cold solder joint, et.al. and particularily on the ground would add heat to the lamp housing. ------ Jerry/Idaho
Jay A	posted 06-22-2003 12:14 PM ET (US) Hot lights are normal! The givaway is if they are mounted in a glass lens. If it's a plastic lens,then I would be concerned.
jimh	posted 06-22-2003 06:55 PM ET (US) Jerry--I sent you an email on this. Also, I think in general you want these navigation lamp fixtures to be well sealed against water entry, so by running hot they are probably indicating that they are fairly air tight and thus well sealed.