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  Topic Review (Newest First)
08-23-2012 10:30 PM
Re: 1500 W 12V Real Sine Wave Inverters?

I expected problems occasionally from our MSW Magnum. I had one, my Mega Super Extra Big knife and tool sharpener wouldn't start.
It turned out that a piece of sandpaper was jammed in a corner of the tool.
08-23-2012 09:23 PM
Re: 1500 W 12V Real Sine Wave Inverters?

Yup, SSBs are not going to be happy with an inverter around. Would be interesting if anyone has feedback after switching brands.
08-18-2012 12:56 PM
Re: 1500 W 12V Real Sine Wave Inverters?

Nothing but perfection from our Magnum.
We had a cheap one first, it didn't last 3 months.
08-18-2012 12:07 PM
Re: 1500 W 12V Real Sine Wave Inverters?

Victron. Will have to check it out. I have a small pure sine wave inverter (don't remember the brand) which raises hell with my SSB/Pactor signals. I have to turn it off to be able to get Wfax. Thanks for the info.
08-18-2012 07:19 AM
Re: 1500 W 12V Real Sine Wave Inverters?

Magnum makes a good unit. Victron makes a superb inverter, one of the few that has almost no EFI which means it can run while using your SSB.
08-18-2012 03:08 AM
Re: 1500 W 12V Real Sine Wave Inverters?

A little late to the discussion, but my two cents: We resell inverters, but excessive return rates on Xantrex make them not worth the bother. Xantrex bought the excellent Heart line many years ago, but they're no longer the same quality, and the Heart guys went off to start Magnum Energy. Xantrex costs a fraction of what the quality units do, but the good ones will last 15, 20 years or (hopefully) more. Interestingly, a charger/inverter costs hardly more than a good inverter once you've hit the 2000w level.
04-21-2012 12:21 PM
Re: 1500 W 12V Real Sine Wave Inverters?

No, really, I've had the pleasure to meet topologists. Square is square, got those nice neat 90-degree corners and uniform trace lengths. Sine isn't. If you push around the lines on a square wave, you get modified square wave. If you make the picture "fuzzy" and somehow you can blur the lines into something that looks like a sine wave--you get modified sine wave. You can do that, the same way you can make a digital version of analog music, by chopping it up into time slices and approximating the curves.

But modified square wave doesn't do that. No matter how much your squint, it never looks "sinish".

And the folks who push it as MSW, also keep muttering vague mystical spells about how important TSW is. At the same time.

Kinda like a florist trying to convince me a bouquet of roses really SHOULD come with all that fresh manure still clinging to the bottom of the bouquet, you know?

I DO hear you, about MSW working so well. And I suspect the old unit I barely remember was plain square wave, not even modified. Still, real sine wave shouldn't be impossible at a lower price point. I think some of the "no name" brands are probably doing this perfectly well, while the branded players are simply making a much larger profit on their true sine wave products.

If I find a modified version, with a good return policy...maybe I will take the chance.
04-21-2012 02:32 AM
Re: 1500 W 12V Real Sine Wave Inverters?

Originally Posted by hellosailor View Post
I took a look at Xantrex's web site, found their "Tech Dr" articles. Found that according to the waveform that they post, their Modified Sine Wave is...a crock. It isn't a modified sine wave at all, it is a modified square wave, no way any kind of emulation of a sine wave. A true "modified sine wave" at least uses multiple steps, multiple pulses, not just a simple square wave with delays. No matter how many vendors pretend it is.
So while their own talk says their MSW will run anything just like a real sine wave...I'm not buyin it. Literally or figuratively. Those guys are talking out of both sides of their mouths. I'll gamble on something else. I've had mixed results with square wave in the past, quite some time back in the past, and if it has a money back guarantee...I may gamble, but not with Xantrex. I don't like smoke and mirrors, and anyone who calls a modified square wave "modified sine wave" can be glad I don't work at the FTC.
HS: Semantics. 'MSW' is rendered as 'modified sine wave' by its proponents, 'modified square wave' by detractors. In the end, it comes down to this, as I said above: NO solid-state, static inverter can produce a true sine waveform. Then it's down to how small & how many are the steps per pi/2 radians, as I said in my post. The basic MSW inverters use about 3 steps per quarter wave. The so-called 'pure' or 'true' sine wave inverters do exactly the same trick, tho at 8x or 16x higher resolution.

If anything, I would accuse them of deceptive advertising, for claiming 'true' and 'pure' when it is no such thing. Educate yourself, and make your choice. ALL static inverters are square wave; some are squarer than others.

My central point is this: don't needlessly buy into the hype around 'pure' sine wave inverters. For most applications, their higher resolution is superfluous. I detailed the loads that mislike MSW. We have now run a full household and professional woodworking shop for nine years on the crudest Xantrex MSW waveform available -- seriously, literally, two steps above square wave. And you know what?

We haven't noticed any squareness.

Really. I'm listening right now to the most pristine remastering of Cannonball Adderley playing 'Corcovado', with an RF-noise-free fidelity to make the heart bleed. We're running the dishwasher, two computers, and some CF lights. Square wave? WHAT square wave?

Point is, MSW (call it modified square, call it modified sine) is good enuf for nearly everything you will plug into it.

Here's another piece of hype to watch out for: don't oversize your inverter(s). Where Wh are precious (as aboard a sailboat), you want your inverter to be large enuf to handle your maximum sustained demands -- but no larger.

Inverters near the top of their range are >90% efficient. With loads below 50% rated capacity, you may see 40-50% efficiency. That means you are expending 2 Ah of battery capacity for every 1 Ah you pull thru the inverter. A rare case where overkill is bad policy. Size your inverter to your median demand. If you exceed its limits, it will let you know -- by kicking a thermal circuit breaker.

So I guess my take-away is this: 1) Don't dismiss crude waveforms because they are crude. Semi-square is probably good enuf for your needs. 2) IF you really want 120VAC power aboard a boat at all (and millions of people get by without), choose the smallest inverter (of either type) that will meet your needs.

Counter-intuitive, but true.

(Honestly, you wouldn't believe the number of people who have told me our off-grid setup cannot possibly work. "You can't run a tablesaw off batteries & MSW. You'd need $10k in TSW inverters." But I researched the hell out of this stuff, chose our systems for robustness rather than bleeding-edge technology, and everything has worked just peachy.)
04-20-2012 11:32 PM
Re: 1500 W 12V Real Sine Wave Inverters?

I've installed, rewired, or replaced inverter/chargers from Xantrex (both Freedom and their newer FreedomHF) and Magnum - all modified sine wave. I have not heard of problems running any load.
04-20-2012 10:26 PM
Re: 1500 W 12V Real Sine Wave Inverters?

I'm running a xantrex square wave 1000watt inverter onboard. FWIW, no problem running/charging laptop , dvd player, drill battery charger.
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