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Old 05-02-2009, 19:04   #1
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electrical problem in main cabin

Hi, so in the past month I have had to replace the light bulbs about once a week in my main cabin. Has any one had a problem like this before? I figure its an electrical issue but don't know where to begin looking.
Any help would be greatly appreciated.
Also, any suggestions on LED lights for the future? I bought one but it seems really dim compared to the bulbs I normally use.

Thanks!
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Old 05-02-2009, 21:17   #2
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Can I assume that the bulbs you're replacing are 12V DC, incandescent bulbs?

If yes, have you checked DC voltage or alternator output? If your voltage regulator is not working correctly you could be burning them out with over voltage.
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Old 05-02-2009, 21:41   #3
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so....how do I check the DC output and/or the alternator? I'm kind of a novice here, so really, dumb it down.

Thanks again!
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Old 05-02-2009, 22:22   #4
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I think that you are getting a surge of wither amperage or voltage. You will need an amp meter preferably one that will record the voltage and attach it to the light fixture. The real question will be what is causing the surge. In my home I had the same problem and I found out that it was a aorn wire in my well casing.
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Old 06-02-2009, 14:26   #5
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The quick, easy test of alternator output is to check the voltage at the battery terminals. Assuming you have a basic volt meter just set to DC Volts and put the red prob on the + of the battery and the black probe on the -. Test first with the engine off and look carefully at the voltage. Then have someone crank the engine while you watch the change in voltage. CAUTION!!! Make sure you the meter and wires are all clear of any belts, pulleys, etc while the engine cranks and runs.

If the voltage goes higher than 13.5-14.0 V then the voltage from the alternator is too high.

You can also check for spikes or surges in the output. This is easier if you have an old fashioned needle type meter instead of digital. Watch the needle or digital readout to see if they bounce up and down a lot.

If things look good at the battery try in the cabin at the power distribution pannel or light sockets in the fixtures where the bulbs are going out. Be careful not to short out a hot to a ground if working in a spot with lots of wires close together.

Testing amps is a little trickier if you have no experience with meters.
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Old 06-02-2009, 14:38   #6
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intermittent connection

Alternator output voltage does not, per se, destroy incandescent bulbs. 14Volts is not too high it is in fact too low for recharging deep-discharge batteries.

Using the Amp-hour law charging method of recovering batteries I have routinely for years used voltages around 15Volts during the process. I have enjoyed very good life on my incandescent "12V" bulbe including a lot of halogen lights. For long life just don't turn them ON when the voltage is high. If they are already on they will not suffer much of a shorter life for the times of the day when recharging batteries.

Long has it been known that rapid on/off cycling of incandescent bulbs results in very short life. Poor connections anywhere in the circuit may cause unnoted sparking which quckly kills the bulb. Look for that problem in breakers, or more commonly switches and sockets or wire connections to them.
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Old 06-02-2009, 15:58   #7
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Quote:
Originally Posted by Rick View Post
Alternator output voltage does not, per se, destroy incandescent bulbs. 14Volts is not too high it is in fact too low for recharging deep-discharge batteries.

Using the Amp-hour law charging method of recovering batteries I have routinely for years used voltages around 15Volts during the process. I have enjoyed very good life on my incandescent "12V" bulbe including a lot of halogen lights. For long life just don't turn them ON when the voltage is high. If they are already on they will not suffer much of a shorter life for the times of the day when recharging batteries.

Long has it been known that rapid on/off cycling of incandescent bulbs results in very short life. Poor connections anywhere in the circuit may cause unnoted sparking which quckly kills the bulb. Look for that problem in breakers, or more commonly switches and sockets or wire connections to them.

Guess my post was a bit unclear and seems for your charging and battery system the limits I gave of 13.5-14.0 V were a little low (although 15V sounds a little high to me but I am not a battery expert), but really high voltage will blow a bulb in a second. Hook a 12V bulk up to 50V and you get an instantaneous pop. I would guess a constant voltage in the 18-20V range could significantly shorten the life of a bulb.

Probably clearer to suggest MaritimeManager look for voltage in that range or higher.
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