Running mains fluorescents from inverter

There is no need for a sine wave inverter. E-ballasts work just fine on DC, and most will probably work on square wave input, though I have not tested this.

Vic Roberts

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More like 30W or less equivalent in a real world comparison.

MBQ

More like 30W or less equivalent in a real world comparison.

MBQ

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and very bad light colour.

mike

Whilst that is likely in the US (I'm always somewhat surprised to see large US supermarket lit with rows and rows of 4' T12 tubes), it's not true here. 4' was a popular size in the home in the 1960's, but in supermarkets and other similar installations, they tend to be 5', 6' or 8' tubes (8' is becoming rarer now), but never 4', possibly because of their low loading compared with the longer tubes. In offices, you can find 4' tubes in 1200x600mm modular ceiling lights, but 2' tubes in 600x600mm modular ceiling lights are much more common. (These are giving way to externally ballasted compact fluorescents now.)

My feeling is that magnetic ballast mains florries fed via an inverter would be very little more efficient than 12 volt halogen lighting.

electronic invertors get over 90% efficiency, the difference between the 2 is huge

Depends entirely where you NEED the light. The LED can provide as much light in a restricted area as the flourescent does - but will NOT light as large an area to that brightness. So the question is - how much light do you need and where??? If the light scattered all over by the flourescent is needed - use flourescent. If it is just wasted (not needed anyway) try the LED solution.

I agree - if the inverter is run in it's "sweet spot" - but if, say, a 1200 watt inverter is used to power a 13 watt load, the efficiency drops WAY DOWN because the quiescent load (what it takes to run the inverter with no load) becomes a sizeable percentage of the total power consumed. - and just how efficient IS a magnetic ballast?? Likely something closer to 80 than 90 - so combine that (let's say

That's miles out. T5 tubes 74-105 lumens/watt, ave 90 Magnetic ballast @80% efficient -> 72 l/w

LED would be good for inspection lamps, desk lamps etc

NT

That may well be their peak efficiency. But driving an inductive load which requires a decent sine wave? And the efficiency of the fittings is likely poorer too if not getting the correct waveform.

It would be very interesting to know the actual efficiency of this setup in practice. I'd say you'd be surprised.

A switche dmode generated sine is highly efficient. If it wasnt, the invertor would cook itself.

NT

Plenty of camping style 12v fluorescents available, and I can totally confirm the battery lasts about 5 times as long as using normal 12v bulbs, since I have both.

Generally 8 or 16watts fittings are less than £20.

Sigh. But that's a custom made 12 volt fitting. Not a low efficiency mains one run off an inverter. Big difference.

i was merely pointing out the obvious way to avoid having to do that.

Depends entirely where you NEED the light. The LED can provide as much light in a restricted area as the flourescent does - but will NOT light as large an area to that brightness. So the question is - how much light do you need and where??? If the light scattered all over by the flourescent is needed - use flourescent. If it is just wasted (not needed anyway) try the LED solution.

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How does distribution affect light colour?

Please re-read and comment appropriately.

mike

Put the figures to it, then you'll know

NT

That's the point I'm making - any figures are likely just a guess when dealing with this unknown. Quoted efficiencies are always under ideal circumstances.

Of course it would be better to use proper low voltage florries or decent LED lighting - but the OP has ruled this out on cost grounds.

We dont have precise figures on the invertor, but low loading isnt going to make a big difference. One can work this out from understanding the way they operate. It is possible to find figures for smpsus.

Short tubes and LEDs both significantly have lower efficacy, and low quality 12v ballasts aren't models of anything. Assuming a mains invertor gets lower total lumens per wattt just isnt logical.

NT

I re-read it, and according to the net-nazi's my response was correct. I bottom posted in response to the "15W LED v 58W Flourescent, not a hope" which was on the same level (>>) as the very bad light colour - so apparently the same message. Get a life!!