Reducing Fluorescent Light Power Consumption

I have had a 2006 Palermo since early this year and am VERY happy with it!
I prefer to stay off grid so have recently changed the halogen bulbs in the 4 spot lights to 1.5W LEDs. In order to further reduce my power consumption from the leisure battery I would now like to reduce the power taken by the fluorescent lights dotted around the Palermo. I have decided not to convert the 2X8W Lumo fittings to LED because the saving in power between fluorescent and LED is relatively small compared to halogen conversion. Instead I'm considering removing one of the fluorescent tubes from some of the fittings (they will be 1X8W) to effectively half both light output (probably not an issue for us in some areas) and power consumption.
My question is - has anyone done such a thing? I'm wondering if the fluorescent driver can run long term with only one tube present?

Any thoughts would be very much appreciated.
Colin

I've never tried it, but I would suggest that it's not likely to be a problem - it may be slightly less efficient (i.e. it may take a bit more than half the power) but I doubt that anything will burn out.

However, IMO a better solution is to replace with LEDs but have two levels of lighting. This is what I have done, with a small push switch in the end of the fitting so that either two or all four LED panels can be powered. This is better (IMO) because fluorescents take a while to warm up, and generally if you turn a light on it's because you want all the light ~now~ and not in a few minutes time! I also much prefer the colour temperature of "warm white" LEDs compared to that of fluorescent tubes...

Many thanks for your prompt response, Mojo.
I'll probably try running one fluorescent tube to see how we get on but would very much appreciate details of the LED "panels" you used and where you sourced them from. I'm guessing you used circular discs with G4 spaced pins?. If the single tube doesn't do it for us I'll use your suggestion.
Many thanks again,
Colin

colin123 wrote:I'm guessing you used circular discs with G4 spaced pins?

Hi Colin - no, I followed the long thread here by Murph, which involved the following type of 48 LED rectangular panel:

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The result typically looks something like this (yes, I know the panels are not in a perfectly straight line, but it doesn't show with the plastic diffuser on, honest!):

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However, I think the Labcraft fittings are particularly well suited to this sort of conversion, and your Lumo fittings may be a bit less so. An alternative would be the replacement tubes which are the same size as your existing ones but LED based. However it's not a simple matter of plug in and go, as you have to bypass the inverter and power them directly from 12V.

The 48 LED panels are very good, but don't underestimate the power consumption and heat generated! I mocked up several different versions on the bench before making the final ones to go in the van. The first try was based on four 48 LED 5050 panels, and it was just too much, both in terms of power consumption and heat generation. The one in the photo uses four 48 LED 3528 panels of which only two are normally on - I typically use all four for reading. I only used three panels in the fitting over the sink/cooker and it is perfectly adequate (about the same brightness as the original two 8W tubes, in fact).

But things continue to develop, and I see they now sell single-chip mini panels with power ratings of 10-100W. I'm sure these could be used with a bit of thought, though heat dissipation is likely to be an issue when putting that much into a small space or under a plastic cover...

Thanks for all the information Mojo - the photo really helps to understand what you've done and the result looks REALLY professional!
I may well be following your route if the simple option of removing a fluorescent tube doesn't do it for us.

Once again thanks for all your input.
Colin

I have replaced all the long tubes with led strip daisey chained ( if you have a look at some of Murphs postings/pictures - similar idea)  I have 2 circular ones to do yet and got the idea off here this or last week

Thanks for the information, Roger. I've looked at Murphs postings and (together with Mojo's input) they have given me inspiration to have a go later in the year.

Many thanks again,
Colin

On my Inca I have converted to LED using self adhesive ones bought on a roll. I have used the tubes to mount the LED,s and disconnected and removed the starter units, but retained the original switches to operate lights, some soldering is required, but the energy saving is worth it. ( 2 times 8 watts becomes 3 watts consumption on LED,s) Good clean lighting is the result.

I had my tube lights converted to LED`s by Atem lighting, not expensive, doesn`t charge for fitting at the shows. I had warm light in the lounge area and cool white in the kitchen, haven`t bothered with the one in the loo, as it isn`t used as much. already had the spotlights done.

If you are an ASOC club member, they have a tech sheet on converting tube lights to LED, I did the extra light I fitted above the passenger seat, connected direct to the leisure battery with a fuse as I did not want to add it to the van system. Did put in a 12 volt regulator chip to compensate for the voltage charge when on hook up.

No ,as my regulated voltage is well within the operating voltage of the LED,s that were used.

Hello Peter, so we're my strip LEDs, but they did get a bit warm, pumping 13.5 volts through them when the battery was charging, now they don't, I think it all depends on the quality of the LEDs.

Hello Redwink
I think you will find that it is the quality of the resistors that are fitted in the LED strip. These will generate heat if they are cheapies. LED,s do not generate heat, as about 98% is converted into light. I hope I am not teaching you how to suck eggs.

Petesymphony wrote:Hello Redwink
I think you will find that it is the quality of the resistors that are fitted in the LED strip. These will generate heat if they are cheapies. LED,s do not generate heat, as about 98% is converted into light. I hope I am not teaching you how to suck eggs.

The amount of heat given off by a resistor is not dependent on its cheapness - it is dependent on its resistance.
LEDs ~do~ generate heat.
LEDs are not 98% efficient, nor anywhere near. For white LEDs, the theoretical best efficiency is in the range 40-45% but in the real world, with current commercial products, you will get nowhere near that.

The Wikipedia page on the subject is a good place to find basic facts about LEDs:

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It's actually (predictably enough) quite a complex subject when you look in detail.

Not at all Peter

Hello Mojo
I was actually referring to the amount of light given out by LED,s in relation to the heat generated and I think that you will find it is about 98% light and 2% heat. Hence the reason you get lots of light and almost no heat. I take your point about resistors, the ones used on my strip are cold even after being on for over an hour. To sum up my units give out light and no measurable heat and of course negligible consumption, which is the point of the exercise.

Petesymphony wrote:I think that you will find it is about 98% light and 2% heat.

I think you will find that you are wrong! Sorry, but I'm not going to agree on this. You may have seen a figure for "luminous efficacy" - I have seen the figure of 98 before, but it's typically given in units of Lumens per Watt - it's not a percentage figure, and it doesn't give any indication of the overall efficiency of an LED.

I can assure you that LEDs do generate heat, and if you don't believe me, try putting your finger on a 2 Watt LED while it is running at rated capacity.

Anyway, the fact is that the current generation of white LEDs has a theoretical maximum efficiency of around 40-45% - though this depends on the method used to generate white light from what is essentially a monochrome source - and real-world applications will yield less than this.

Incidentally, it's also commonly said that LEDs are a massive improvement over fluorescent lamps in terms of efficiency, but in reality the difference is not that great - once they are warmed up and at full output, fluorescent tubes are actually pretty efficient! The main reason I replaced mine with LEDs is that I don't like the dimness during the first few minutes (plus I also don't like the colour temperature of the small fluorescent lamps).

Hi  

-mojo- wrote:LEDs ~do~ generate heat.

They certainly do and if the lamp isn’t designed and driven properly they get very hot indeed. The problem is that although you get a lot of light for a given wattage that wattage is dissipated in a very small area causing a large temperature rise and making thermal management (conducting heat away from the device to lower its temperature) crucial.

Cree give the maximum working temperature at the junction as 150°C although obviously LED modules are designed to operate at much lower temperatures. That is for a specific product, but of semiconductor devices in general have a maximum junction temperature in that sort of area.

In many commercial LED modules, if you look at the PCB you see that it’s very thin and mounted on a metal backing so that the metal acts as a heatsink.

Anyone interested in such matters will find this application note from Cree interesting:

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-mojo- wrote:The amount of heat given off by a resistor is not dependent on its cheapness - it is dependent on its resistance.

Can’t argue with that but let’s not get confused between heat and temperature, they are very different. You mean heat as in energy but to be a useful measurement in this context we have to quote it over time  i.e. Joules per second = power = Watts.

The power the resistor dissipates is fixed by the resistance (given constant voltage) but the temperature it gets to depends on how quickly it can conduct energy away and that depends largely on its size (there are lots of other factors as well). If a resistor is overheating it’s wattage rating is too low for the conditions it’s being used in.

Brod

I've also got their tubes and very happy with the brightness but was not aware of the link so you can use just one tube.

Hi Paulmold, the link is effectively only two fluorescent tube end caps linked by a thin piece of wire to act as another tube, but it works.  They advised me to do it that way to save money and eyesight

Does anyone actually use all their fluorescent fittings to light the van, I've converted all our fluorescent lighting (including the long pelmet lighting) to LED by using strips and replaced the spotlights with 1W LED spots (as well as adding one to the underside of the sink/cooker cupboards).

We find that we almost never use the main lighting, except for a few minutes at a time just to make the bed or find something under the seats. We invariably use the spots for reading, watching TV (on the very rare occasion) and before we're ready to drop off to sleep.
Even when cooking or washing up, the single spotlight is better illumination than the oval strip light.

I have to say - even though our van looks like Blackpool illuminations with all the interior lights on, I'm still planning to install some colour changing remote controlled LED strips under the windows where the spotlights are. You never know, it might get SWMBO 'in the mood' once in a while.

Seriously though, do we all need or use all this lighting, we certainly don't.

We use the spots converted to LED to light the van when off grid or metered mains and the fluorescent as needed in toilet or bathroom.

The coin in the slot Stellplatz hook ups often have enough left for overnight fridge and lights. 
Yes I know it's mean but now that  we are getting less euros ....

meanchris wrote: I'm still planning to install some colour changing remote controlled LED strips under the windows where the spotlights are. You never know, it might get SWMBO 'in the mood' once in a while.

Does anyone know if you can get those shiny chrome table poles that will reach all the way to the van ceiling ! 

NORGIL wrote:

meanchris wrote: I'm still planning to install some colour changing remote controlled LED strips under the windows where the spotlights are. You never know, it might get SWMBO 'in the mood' once in a while.

Does anyone know if you can get those shiny chrome table poles that will reach all the way to the van ceiling ! 

I'm hoping that SWMBO doesn't read this thread, or that's not the only place it would be reaching.