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UK diy (uk.d-i-y) For the discussion of all topics related to diy (do-it-yourself) in the UK. All levels of experience and proficency are welcome to join in to ask questions or offer solutions. |
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#1
Posted to alt.energy.homepower,sci.engr.lighting,uk.d-i-y
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Running mains fluorescents from inverter
In article ,
The Other Mike wrote: The other half of the site has 5ft T5's with magnetic ballasts fed by a Honda EU20i generator which despite being a quiet suitcase model and loads of additional soundproofing is still way too noisy. Near silent operation is essential. Hauling fuel is also a PITA as its a long way from the road. So I need a way of powering the 5ft T5's (58W) from a low voltage DC supply. IOTA only make ballasts up to 40W and they need a circa 50v supply, realistically I need to keep to 12v to keep the solar array price down. My feeling is that magnetic ballast mains florries fed via an inverter would be very little more efficient than 12 volt halogen lighting. -- *Save a tree, eat a beaver* Dave Plowman London SW To e-mail, change noise into sound. |
#2
Posted to alt.energy.homepower,sci.engr.lighting,uk.d-i-y
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Running mains fluorescents from inverter
On Jun 23, 12:11*am, "Dave Plowman (News)"
wrote: In article , * *The Other Mike wrote: The other half of the site has 5ft T5's with magnetic ballasts fed by a Honda EU20i generator which despite being a quiet suitcase model and loads of additional soundproofing is still way too noisy. *Near silent operation is essential. *Hauling fuel is also a PITA as its a long way from the road. So I need a way of powering the 5ft T5's (58W) from a low voltage DC supply. *IOTA only make ballasts up to 40W and they need a circa 50v supply, realistically I need to keep to 12v to keep the solar array price down. 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 |
#3
Posted to alt.energy.homepower,sci.engr.lighting,uk.d-i-y
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Running mains fluorescents from inverter
On Wed, 22 Jun 2011 17:51:40 -0700 (PDT), Tabby
wrote: On Jun 23, 12:11Â*am, "Dave Plowman (News)" wrote: In article , Â* Â*The Other Mike wrote: The other half of the site has 5ft T5's with magnetic ballasts fed by a Honda EU20i generator which despite being a quiet suitcase model and loads of additional soundproofing is still way too noisy. Â*Near silent operation is essential. Â*Hauling fuel is also a PITA as its a long way from the road. So I need a way of powering the 5ft T5's (58W) from a low voltage DC supply. Â*IOTA only make ballasts up to 40W and they need a circa 50v supply, realistically I need to keep to 12v to keep the solar array price down. 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 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 80) with the (possibly) 70% efficiency of a lightly loaded inverter, and you are down to about 56% efficiency - where, particularly for task lighting, a low voltage halogen is DEFINITELY worth considering. (and an LED positively SHINES.) (pun intended) |
#4
Posted to alt.energy.homepower,sci.engr.lighting,uk.d-i-y
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Running mains fluorescents from inverter
On Jun 23, 3:54*am, wrote:
On Wed, 22 Jun 2011 17:51:40 -0700 (PDT), Tabby wrote: On Jun 23, 12:11*am, "Dave Plowman (News)" wrote: In article , * *The Other Mike wrote: The other half of the site has 5ft T5's with magnetic ballasts fed by a Honda EU20i generator which despite being a quiet suitcase model and loads of additional soundproofing is still way too noisy. *Near silent operation is essential. *Hauling fuel is also a PITA as its a long way from the road. So I need a way of powering the 5ft T5's (58W) from a low voltage DC supply. *IOTA only make ballasts up to 40W and they need a circa 50v supply, realistically I need to keep to 12v to keep the solar array price down. 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 *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 80) with the (possibly) 70% efficiency of a lightly loaded inverter, and you are down to about 56% efficiency - where, particularly for task lighting, a low voltage halogen is DEFINITELY worth considering. (and an LED positively SHINES.) (pun intended) That's miles out. T5 tubes 74-105 lumens/watt, ave 90 Magnetic ballast @80% efficient - 72 l/w 70% efficient invertor - 50 l/w 12v Halogen 24 l/w LED would be good for inspection lamps, desk lamps etc NT |
#5
Posted to alt.energy.homepower,sci.engr.lighting,uk.d-i-y
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Running mains fluorescents from inverter
In article
, Tabby wrote: 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 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. -- *Did you ever notice when you blow in a dog's face he gets mad at you? * Dave Plowman London SW To e-mail, change noise into sound. |
#6
Posted to alt.energy.homepower,sci.engr.lighting,uk.d-i-y
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Running mains fluorescents from inverter
On Jun 23, 10:53*am, "Dave Plowman (News)"
wrote: In article , * *Tabby wrote: 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 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 |
#7
Posted to alt.energy.homepower,sci.engr.lighting,uk.d-i-y
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Running mains fluorescents from inverter
Tabby wrote:
On Jun 23, 10:53 am, "Dave Plowman (News)" wrote: In article , Tabby wrote: 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 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. 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. http://www.the12voltshop.co.uk/Shop/...escent-lights/ NT |
#8
Posted to uk.d-i-y
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Running mains fluorescents from inverter
In article ,
The Natural Philosopher wrote: 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. 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. Sigh. But that's a custom made 12 volt fitting. Not a low efficiency mains one run off an inverter. Big difference. -- *The man who fell into an upholstery machine is fully recovered* Dave Plowman London SW To e-mail, change noise into sound. |
#9
Posted to alt.energy.homepower,sci.engr.lighting,uk.d-i-y
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Running mains fluorescents from inverter
In article ,
Tabby writes: On Jun 23, 10:53*am, "Dave Plowman (News)" wrote: In article , * *Tabby wrote: 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 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. It's efficient into a resistive load. A magnetically ballasted fluorescent lamp isn't a resistive load. Even if it has a power factor correction capacitor (and most don't nowadays), that can only correct the inductive component in the power factor, not the contribution from the tube, which amounts to about half of it. The inverter cannot recover the excess energy borrowed from it and returned each half cycle due to the phase shift, so the load on the inverter is much nearer to the (higher) VA rating of the lamp than the power rating. (That's why inverters are rated in VA and not Watts.) -- Andrew Gabriel [email address is not usable -- followup in the newsgroup] |
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