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Old 27-07-2008, 18:19   #1
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Primer on inverters...

Could somebody give me a super brief primer on inverters? I was out at Fry's today and the selection was overwhelming. Other than the peak and sustainable load numbers- what should I know? Is there a serious efficiency loss when running something through an inverter?

Thanks,
J
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Old 27-07-2008, 18:28   #2
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This is pretty helpful but feel free to expound...

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Old 27-07-2008, 21:35   #3
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Its always better to have an inverter that creates a true sine wave. Some electronics are sensitive to the inverters that create a square wave with the corners lopped off. Or what they call a "modified sine wave" which is a misleading term at best....because it never was modified from a sine wave. It is modified from a square wave.
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Old 29-07-2008, 01:23   #4
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A reasonable rule of thumb is you get what you pay for. Pure sine wave units require some expensive parts and thus are expensive. Modified comes down to how much the square wave is modified. That takes components which equals money. Cheap equals poor sine wave quality and expensive equal better. Having said that, there is little that won't run of a cheapy these days. I had a cheap Asian unit 3000W cont, 6000W peak and everything I had ran off it.
A microwave oven is the biggest draw. It requires 3x the cont. run current to start the magnatron running.
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Old 29-07-2008, 06:57   #5
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Magnatron? Is that some kind of giant robot that turns into a helicopter or something?
[A Magnetron is a device that generates microwaves, such as utilized in RADAR & Microwave Ovens.]

So, some devices might be finicky and not run with cheap inverters even if they are within its "supported" wattage range? Probably most off the shelf consumer stuff is fine though yeah?

I thought I read somewhere that there was an efficiency loss when going through the inverter? Is this significant enough to change my power need calculations?

Thanks guys,
JL
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Old 29-07-2008, 16:50   #6
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I have a Xantrex ProSine 2.0 (pure sine wave over $1000) and the cheap 400W modified sine wave inverter from West Marine (under $50). We have a 23" LCD TV that works perfectly on the Xantrex but there is a buzzing sound and faint horizontal waves through the picture when running on the cheap inverter. It certianly doesn't make the TV unusable but it is noticable. I completely agree that you will get what you pay for when it comes to inveters.

We see close to 90% efficiancy out of our Xantrex and it draws about 1 amp when it is on and nothing is drawing 110V. Keep in mind that the efficiany rating is achived at a certian load (maybe around 80-90% of rated continuous load?). So a 90% efficiant inverter designed for 3000W will not run that efficiantly when drawing only 50W.
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Old 10-08-2008, 21:15   #7
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This is my experience...
I had a good quality modified sine wave inverter.
The old microwave worked fine , the new one , not at all. My electric toothbrush charger lasted 1 week before it stopped working, I thought it may have fallen one the floor so I bought a new one, same thing again. Cheaper inline laptop transformers made buzzing sounds which always worried me.
The toothbrush incidents convinced me to buy a true sine wave. Now everything works fine.
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