Posted by clare on June 23, 2011, 2:54 am
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)
Posted by Tabby on June 23, 2011, 5:39 am
On Jun 23, 3:54am, cl...@snyder.on.ca wrote:
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
Posted by Dave Plowman (News) on June 23, 2011, 9:53 am
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 firstname.lastname@example.org London SW
To e-mail, change noise into sound.
Posted by Tabby on June 23, 2011, 11:50 am
A switche dmode generated sine is highly efficient. If it wasnt, the
invertor would cook itself.
Posted by The Natural Philosopher on June 23, 2011, 12:19 pm
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.