Inverter question

[Newshound]

I use an inverter and a couple of leisure batteries to provide up to about 50 watts of lighting using CFLs for my stables. It's never used for more than an hour or so a day even in mid-winter, so not heavy use, and the individual lights tend to get switched on in sequence as and when required to maximise battery life. I recognise that CFLs are not a resistive load, but the latest inverter was rated 350 W continuous 600W peak and I would have thought that this should cope.

But, I've had two inverters fail in three years. I've only been using cheap inverters from eBay or other internet sources. Have I just been unlucky? Can anyone suggest a supplier for more robust inverters?

[Andrew Gabriel]

I would use 12V CFL's, or other 12V fluorescent fittings (and possibly LED, depending on the situation). Even 12V halogens are worth considering.

[Newshound]

What a good idea! I'd never come across 12v CFLs. I can even get them with B22 caps so that I don't have to change the existing sockets.

[Dave Plowman (News)]

It's rather an inefficient way to do things. Far better to use lights designed for 12 volts direct. Plenty of caravan etc fittings out there. Probably an even wider selection if you go to 24 volts - trucks and coaches, etc.

Are they well cooled? It's usually overheating that kills them.

[Paul D Smith]

Probably OK but do check the current - 50W at 12V is getting on for 5amps. Can your wiring handle this?

Paul DS.

[Newshound]

They have fans, good access to air, and big heatsinks and I've only been running at a fraction of the rating. Have identified the probable failure, one of the DIL chips. Looked for replacement: £1-40 from Farnell with minimum £20 order, a pair from RS at £1-60 each, ten from China for £6 including postage, or one from the States at £1 plus £6 postage.

But then Andrew came up with the better idea.

[Newshound]

Good point, but I have effectively separate radial circuits using 0.5 mm^2 flex for each 11W bulb, so should be OK although there will be a bit of voltage drop. Currently using a switched spreader with 13A plugs, hopefully less than 1 amp DC should be OK on these switches and plug contacts. Can go over to boat/caravan plugs and sockets if necessary.

Point worth making, though.

[Bill Wright]

In my experience it's best to run 12V halogens, etc, at no more than

11.5V. They last much longer.

Bill

[Dave Plowman (News)]

They might do but will be much less efficient. And that could be important with running from batteries. Where the energy is even more expensive than mains.

[Brian Gaff]

Depends how long the cable run is of course as to how much voltage drop you will get on existing cables. Brian

[NT]

As has been said, I'd go 12v, unless the wiring is exceptionally long. But forget halogens, they're most inefficient, will gobble your battery charge and require thicker wire. LEDs are great for low wattages, maybe upto 10w, CFLs are good for the equivalent of upto

100w in filament terms, and fluorescent are good for about 20w up. Low power linear fl fittings often kill tubes prematurely, and have much less efficiency than their larger brethren.

NT

[Bill Wright]

This is interesting. When I built my motorhome I looked for an alternative to fluos and tested halogens. These were 12V AC domestic units, but I was running them on 12VDC. I compared efficiencies watt for watt and concluded that there wasn't much in it. Id expected the fluos to win by a mile, but they didn't. I think part of it is down to the fact that halogens, even wide angle ones, don't waste light the way fluos do by illuminating the ceiling etc. Anyway, I used halogens and they've been fine.

LEDs are great for low

That's probably why I got the results above then.

Bill

[NT]

he equivalent of upto

You can put reflectors on fluoros too, albeit it in one axis not the other. You should then see a lot better result - but linear fls arent well suited to spotlighting. LEDs are, and will beat the pants off halogen.

NT

[Andrew Gabriel]

There isn't - 12V halogens in the 20-35W range are at the peak of halogen efficiency, and are same as cheap retail LEDs. Of course LED's are available at much higher efficiencies, but not for a few quid.

The small 4/6/8W fluorescents are not efficient by today's standards - too much lost in the cathode fall voltage compared with the power actually going into the discharge. If you go up to 4' 36W or the high efficieny T5 tubes (14W and up), then you have something quite efficient. The 13W T5 tube is OK too, providing you get a modern triphosphor one and not an original halophosphate one.

[Bill Wright]

My problem is, I strongly prefer continuous spectrum lighting.

Bill

[Dave Plowman (News)]

That's not a problem with fluorescent - but you'd be into specialist tubes which probably are difficult to get especially in these uncommon sizes. But they do exist.

LED? Forget it. At the moment.

[Andrew Gabriel]

They're also significantly less efficient than triphosphor tubes.

[Bill Wright]

Halogens give a lovely light.

Bill

[Dave Plowman (News)]

They do. But in my kitchen I have under cupboard fluorescents which match the light from them pretty well. Using custom tubes. Which aren't noticeably duller than the more common ones.

Fluorescents have been used for location filming for some time now - and poor colour rendering due to non continuous spectrum lighting shows up even more on camera than to the eye. However, you won't find the tubes in B&Q.