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Author Topic: 6V or 12V lights?  (Read 2333 times)

Richdef

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6V or 12V lights?
« on: January 08, 2008, 09:48:58 AM »

Hi all,

Are 6V or 12V grain of wheat bulbs better?

I am going to be using 2No. 6V batteries so could use either voltage.  Is there any difference / preference on which voltage is better.  Does one offer better bulb life?  Is there any difference in brightness etc?

There will be a number of bulbs in the circuit(s) including bulkhead, searchlights and nav lights.   

cheers for the help

Richard     
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RickF

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Re: 6V or 12V lights?
« Reply #1 on: January 08, 2008, 10:33:43 AM »

Have you considered LEDs? Less current drain and brighter too.

Rick
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FullLeatherJacket

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Re: 6V or 12V lights?
« Reply #2 on: January 08, 2008, 10:44:28 AM »

Richard
There's not a fat lot of difference in light output, if any. Reasonably-priced 12v GOW bulbs are available in more colours. Current drawn is typically 80mA for the 12v and 62 mA for the 6v. You pays your money and you takes your choice.
FLJ
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Richdef

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Re: 6V or 12V lights?
« Reply #3 on: January 08, 2008, 10:55:17 AM »

Rick had looked at LEDs but was heading towards the bulbs to avoid having the stiff legs - more akward to work with.

FLJ thanks for the info will have to see how the rest of the wiring is looking - may go for 12V to keep the loads on the batts even

Cheers all  O0
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portside II

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Re: 6V or 12V lights?
« Reply #4 on: January 08, 2008, 12:47:30 PM »

the other thing you may wish to concider is the brightness of the bulbs ,if you use the correct voltage for the right bulb then you may find that they give off too much light (12v bulb on 12v, 6v bulb on 6v NOT 6V BULB ON 12V  :o ).
Also these bulbs give off heat as  a by product and the more voltage (up to the rated type) supplied the more heat generated ,some people may like sailing their craft on an evening and having the lake/pond lit up by high intensity lighting ,but i prefer a gentile form of illumination.
So if you plan to fit GOW bulbs in your wheel-house then why not fit 12v bulbs and run them off 6v .
Another method mentioned is LED's ,great advantage of a lower power consumption but get the voltage wrong and you dont get a second chance .
the other thing with LED's is that you can wire them up in multiples so that you can run directly off your desired voltage ,at the moment on my Dutch River tug i have 10 LED;s on the mast (various colours) and 4 12v GOW bulbs in the wheel-house roof  so far and  they all run from a 12v battery with only 2 diodes to drop the voltage ,and there will be more lights (LED's) to be fitted .
To get around the problem with LED;s giving off too much light i cap them off with pannel mounted diffusers ,they soffen the light and make nice covers  

daz
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banjo

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Re: 6V or 12V lights?
« Reply #5 on: January 08, 2008, 02:03:00 PM »


" run from a 12v battery with only 2 diodes to drop the voltage "

I thought diodes were "one way" switches and you put resistors in the circuit?

Isn't it even?

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banjo

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Re: 6V or 12V lights?
« Reply #6 on: January 08, 2008, 02:40:11 PM »

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portside II

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Re: 6V or 12V lights?
« Reply #7 on: January 08, 2008, 04:47:39 PM »

oops  :embarrassed:  thats what i ment to type but the keyboard moved the letters around  {-)
yeh resistors ,one for the coloured ones and one for the four white ones .
daz
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Martin [Admin]

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Re: 6V or 12V lights?
« Reply #8 on: January 08, 2008, 05:00:58 PM »

LED are very good  but are Very directional i.e. can best seen from al most head on.
Filament bulbs get hot and will need replacing at some stage but do have a much better omni directional light output.
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Colin Bishop

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Re: 6V or 12V lights?
« Reply #9 on: January 08, 2008, 05:09:32 PM »

Filament bulbs will last longer if run at less than their stated voltage. If you think running 12v bulbs at 6v would be too dim then maybe use one of th0se voltage converters used to step down a 12v car cigarette lighter supply to various voltages, somewhere between 7v and 9v should be fine.
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Bunkerbarge

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Re: 6V or 12V lights?
« Reply #10 on: January 08, 2008, 07:13:23 PM »

My steamer lights are imitating oil lamps so I've previously had them set them up with 12v lamps connected to 6v.  That proved to be too dim so I'm going to run them off a 7.2 pack which looks fine.

They are all sealed in so when they fail that's it, hence the reduced voltage to give the correct effect and prolong life.
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Richdef

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Re: 6V or 12V lights?
« Reply #11 on: January 09, 2008, 12:52:53 PM »

thanks all for the ideas and help  O0
i think im gona go with the 12v GOW bulbs on a reduced voltage to inprove life. 
now the only prob is finding the time to get all done - GRRR to work takes up too much time!
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OMK

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Re: 6V or 12V lights?
« Reply #12 on: January 10, 2008, 09:25:37 AM »

I thought diodes were "one way" switches and you put resistors in the circuit?

Isn't it even?

Banjo,
I think what he's saying is the diodes are there to reduce the voltage a little (resistors reduce current.). A bog-standard silicon diode, in series with the battery, will drop the voltage by around 0.6 to 0.7 volts. In other words, in order for the diode to let current pass, it needs at least 0.6 volts before it starts to conduct. So his two series diodes are dropping around 1.2 - 1.4 volts of battery juice before it reaches the LED. And don't forget... Just as LEDs are diodes, they also need a certain amount of juice in order to conduct. A standard red, yellow or green LED will need at least 2 volts. The white and blue jobs need at least double that.
But if he's using two series-connected 6-volt batteries, with two series diodes, it means his 10.6 volts (12v minus 1.4v) is still waaaay too much juice to shove up any LED - especially without connecting its appropriate current limiting resistor in series first.

Rich Def,
In case you need a bit of help, I'd advice you scrap the series diodes then use a single resistor instead. All you need to ascertain the required value is........

1) First of all, deduct your LED voltage from your battery voltage. For instance, if you're using a standard 5mm red LED connected to your 12v supply, you simply deduct 2 from 12.

2) Now you need to work out how much current you want to pass through the LED. More current means the LED glows brighter. But the pay-off is that more current also means more of a drain on your batteries. Most LEDs will need approx' 10mA to 50mA in order to glow (that's 0.01 Amp to 0.05 Amp). You'll probably find that 20mA is a good compromise between brightness versus current drain. So let's assume 20mA is to be your required current draw.

3) Now that you're armed with two variables makes it easy to calculate the third. The first var' being the voltage (10 volts), and the second var' being the current draw (20mA). So in this case, the third variable - the unknown variable - is the required resistance value. You simply divided 10 by 0.02. The answer = 500. That means a resistance of 500 Ohms. The nearest practical value in terms of real-life resistor values would be 470 Ohms or 560 Ohms. Common practice is usually to use the next highest value.

After that comes another variable.... Watts.
Watts is calculated by multiplying your battery voltage by the amount of current that all your LEDs are pulling. Shan't bog you down with anymore techn' blurb, other than to say that, as a rule o' thumb, you can use one-quarter Watt (or even the smaller one-eighth Watt) resistors for parallel-connected LEDs. But series-connected LEDs means you'll need a beefy'er-wattage. Generally, a half-watt job would cover lost needs. If it gets warm, use a 1-Watt.


You read it here first.
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portside II

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Re: 6V or 12V lights?
« Reply #13 on: January 10, 2008, 02:06:44 PM »

AHA THATS WHY IT STILL WORKED  O0
DAZ
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