Lighting for isolated cottage

[robgraham]

I had a query from my electrically competent brother about a guy he went to visit who lives in an isolated cottage with on site generation.

The guy is not that knowledgeable and was having difficulty with losing charge in his batteries. The generation sources are all 24 vdc.

Seemingly the electrics are 'untidy' so we can guess this is a pretty ad hoc system !

He has an inverter to 240vac which is quite large but very under-loaded - small TV and of all things 240v LED lights. The suggestion was that this would run inefficiently at light loading - true?

I did wonder about running all the lighting as 12v LED's but that would mean tapping into half the battery bank, but realised later that might cause charging problems.

I believe large caravans run on 24v systems, small boats too perhaps. What lighting do they use ?

The other attraction in the 12v system is that a car inverter would match the TV load better.

Rob

[Adrian]

You probably want to start looking at large motorhomes, trucks, coaches. HGVs tend to be 24v, cars 12v.

[Dave Plowman (News)]

I'd guess he simply doesn't realise just how little a battery or two stores. And converting low volt DC to 240v to runs things which could run from low volt DC a nonsense.

It's not difficult to work out the amount of load you'd like your batteries to run for a given period of time. And when you do, you'll find another option.

[spuorgelgoog]

yes, very inefficient for low loads as there is a considerable standing loa d:

"The other golden rule with inverters is to switch them OFF when you don't need 230 power. They all consume valuable power (around 2 amps typically) j ust sitting in idle mode, though some new inverters do have a standby funct ion that reduces this I would still adopt the mantra of if you don't need i t right now TURN IT OFF."

12V or 24V fluorescents are probably the most efficient lighting to run dir ect from battery for larger rooms, with occasional LEDs for corridors and s tairs.

That narrowboat site has a forum where power issues seem to be discussed a fair bit.

Owain

[Bill Wright]

Actually or nominally? They need to be about 28V to do any good.

There's a residual current draw, which is small, and the fan if it isn't thermostatically controlled.

Some inverters go to sleep unless there's a load. The residual draw from them is minuscule.

that might cause charging problems.

That's a really bad idea.

Use 24 to 12V conversion

We use the 7A ones in large quantities. They are very good.

Or put the the 12V LEDs in groups of two, in series. That is tried and tested by me and it works fine. I have done 29 pairs for me and mates with no problems.

You can get 24V fluorescents. Forget all the 24V tungsten and halogens. They are too ineffiecient for battery use. LEDs are the best really, but avoid the nasty coloured ones. Get warm white ones.

Best way with tellys is to have a small dedicated true sine inverter,

24V of course, just for the telly and recorder. Turn it off when not in use.

Bill

[Dave Liquorice]

As others have said there is some standing load from an invertor. If you don't need 240 V turn it off, as in off off not standby off. As for running 240 V LEDs from it that is just plain bonkers, every storage or conversion stage has losses. If you have a restricted resource you don't want to waste it...

Also mentioned is that trucks ect tend to be 24 V. You can get 24 V TV's, microwaves and no doubt lighting. I'd look closely at the power demand of flourescent v LED and the light output. They are close, starting from scratch I'd proably go for LED these days but just "upgrading" isn't worth it, yet.

[meow2222]

to visit who lives in an isolated cottage with on site generation.

harge in his batteries. The generation sources are all 24 vdc.

small TV and of all things 240v LED lights. The suggestion was that this would run inefficiently at light loading - true?

ean tapping into half the battery bank, but realised later that might cause charging problems.

at lighting do they use ?

the TV load better.

Much has been said already, I'll just see if I can add anything more.

I'd measure & log 24v current draw to see if the batteries are dying or fin e.

Lighting: linear fl is still the most efficient, but pick tubes with a bit of care, they cover a wide efficiency range.

For low powers use LEDs. You can get away with extremely low light levels i n some areas. Either use 24v, or 12v in series, or 12v via a switched mode regulator.

If you need to take it even further and have family in the house, its possi ble to use low v PIRs to switch off lights when someones out of range. You can also use outdoor reflectors to delay lighting switch on a bit.

Finally don't overlook gas lighting. Its cheaper to run that onsite generat ion, cheap to buy and far more reliable. It also doesnt use costly battery capacity. It does kick out a lot of heat - a good combination for winter us e, with the lighter summer load all electrical.

NT

[robgraham]

t to visit who lives in an isolated cottage with on site generation.

charge in his batteries. The generation sources are all 24 vdc.

d hoc system !

- small TV and of all things 240v LED lights. The suggestion was that thi s would run inefficiently at light loading - true?

mean tapping into half the battery bank, but realised later that might cau se charging problems.

What lighting do they use ?

ch the TV load better.

t of care, they cover a wide efficiency range.

in some areas. Either use 24v, or 12v in series, or 12v via a switched mod e regulator.

sible to use low v PIRs to switch off lights when someones out of range. Yo u can also use outdoor reflectors to delay lighting switch on a bit.

ation, cheap to buy and far more reliable. It also doesnt use costly batter y capacity. It does kick out a lot of heat - a good combination for winter use, with the lighter summer load all electrical.

Many thanks everyone - there is a lot of useful information there, and I've passed the link for this to my brother. Duty done by me, Boy Scout badges for you and it's up to brother now to help his friend. Rob

[dr.s.lartius]

For a possible cheap, easy, but minor improvements :-

Ensure that all lamp shades and all surfaces near lamps are as nearly white or reflective as the situation allows.

[Bill Wright]

Also, an easy way of dimming the lights when you want a cosy evening is to paint the ceiling and walls black. Don't forget to paint them white again though before you go to bed.

Here's another tip. To save wear and tear on your light switch, just paint the bulb black when you want the light off.

Bill

[meow2222]

Its surprising how many lampshades aren't white.

NT

[Dave Plowman (News)]

Given the idea is to shade the light, not surprising. If you want the maximum light, a naked bulb etc is the way to go.

[meow2222]

AIUI the idea is to diffuse or redirect light. Absorbing most of it seems a bit counterproductive.

NT

[polygonum]

People who make traditional cloth lampshades over copper wire frames are usually advised that white fabric is a disaster. Ends up looking horribly blue and harsh. Even the tiniest shift towards a softer colour and all seems well.

[Dave Liquorice]

Or very thick. White walls and ceilings does make a big difference to the light level in a rrom. Our boiler room is window less, it was bare stone/plaster and grey (sooty from previous boiler) ceiling. After finishing a ceiling elsewhere I "cleaned" the roller on the boiler room ceiling boy did it mak an instant difference. I now always "clean" rollers used for white in there...

I wouldn't want to live in a white room though.

[The Natural Philosopher]

[Dr J R Stockton]

In uk.d-i-y message , Mon, 11 Aug 2014

16:52:00, "Dave Plowman (News)" posted:

Yes, but then one can get dazzled by a direct view of the bulb, causing the eye to stop down and so reduce the visibility of what one is about to trip over. There should be no absorption of light, and no specular reflection, by the shade. For lighting a room, use a translucent shade; for a reading light, an opaque one.

For safety, dye the cat tabby, unless it is naturally so.

[Dave Plowman (News)]

So use a fluorescent. Much more efficient anyway.

Of course there is. It lowers the light levels to the parts the light has to get through it to hit. Without adding to the other parts.

[Dr J R Stockton]

In uk.d-i-y message , Thu, 14 Aug 2014

00:10:26, "Dave Plowman (News)" posted:

For maximum efficiency, one should use a partially reflecting (diffusing) shade rather than a partially opaque one. Photons should not be unnecessarily absorbed.

with a white interior.