Very dim lights in 93 Harmony

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Very dim lights in 93 Harmony

Post by shawgough on Thu Mar 10, 2016 1:45 pm

Hi again

The habitation lighting in our newly acquired 1993 Harmony are really really dim. Particularly the strip lights in the dinette area and at the back.

Is this a common thing or do the tubes need replacing, or is there something else wrong?
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Re: Very dim lights in 93 Harmony

Post by boxerman on Thu Mar 10, 2016 2:14 pm

Is your leisure battery fully charged?

Frank
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Re: Very dim lights in 93 Harmony

Post by shawgough on Thu Mar 10, 2016 2:52 pm

It is the same when on hook up.
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Re: Very dim lights in 93 Harmony

Post by boxerman on Thu Mar 10, 2016 3:12 pm

Try changing just one and see if it makes a difference.

Frank
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Re: Very dim lights in 93 Harmony

Post by shawgough on Thu Mar 10, 2016 3:34 pm

boxerman wrote:Try changing just one and see if it makes a difference.

Frank


Thank you Frank. You're very good at this.
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Re: Very dim lights in 93 Harmony

Post by richardstubbs on Thu Mar 10, 2016 6:53 pm

Also, those old strip lights are very dim in the cold. Ours are, but they're fine once the van is nice and toasty inside (thanks to the Propex).

Are they like these:


If so, they're the same as in the Rapport, and they'll probably be fine once the nice weather comes. If it does...
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Re: Very dim lights in 93 Harmony

Post by shawgough on Thu Mar 10, 2016 8:32 pm

Yes. Exactly the same. Why are they dim in the cold?
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Re: Very dim lights in 93 Harmony

Post by shawgough on Thu Mar 10, 2016 8:34 pm

Also, we'll be in Spain soon so the lights will be fine!
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Re: Very dim lights in 93 Harmony

Post by richardstubbs on Sun Mar 13, 2016 7:18 pm

Hopefully :)

I feel as though I should know why they're dim but I don't. Same reason CFL (energy saving) lamps are useless as outside lights I guess. I seem to recall that there's something about the more efficient fluorescent compounds working better at higher temperatures, but beyond that..
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Re: Very dim lights in 93 Harmony

Post by bill.teager on Sun Mar 13, 2016 8:38 pm

if on hook up have you tried with battery charger switched on
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Re: Very dim lights in 93 Harmony

Post by brodco on Sun Mar 13, 2016 8:54 pm

Hi wave

As I understand it: scratch head

It's because they are a kind of low pressure mercury vapour lamp. The tube contains an inert gas (e.g. argon) and mercury vapour.   When the lamp strikes, current flows through the mercury vapour and that generates ultraviolet light. The ultraviolet light excites the fluorescent coating on the inner walls of the tube which in-tern produces visible light.

The problem is that at low temperatures the partial pressure of mercury vapour is low with some of the mercury condensing out as mercury droplets inside the tube. As the temperature rises the mercury vaporises again, and the partial pressure  increases. That leads to increased current flow and the lamp becomes brighter.

As a double whammy the fluorescent coating is also less efficient at low temperatures. You can't get rid of the effect but tubes certainly get worse with age so I think it's worth trying Franks suggestion of replacing one lamp to see if it's any better.

Incidentally I find that if I leave mine on long enough the self heating effect gets them going after a while.

Brod


Last edited by brodco on Sun Mar 13, 2016 9:40 pm; edited 1 time in total
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Re: Very dim lights in 93 Harmony

Post by shawgough on Sun Mar 13, 2016 9:17 pm

Thanks folks
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Re: Very dim lights in 93 Harmony

Post by brodco on Sun Mar 13, 2016 9:39 pm

Sorry extra post tap_fingers  in error.
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Re: Very dim lights in 93 Harmony

Post by shawgough on Mon Mar 21, 2016 5:18 pm

Having the lights on while driving all day seems to make them brighter.
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