MSW vs. sine wave options with inverters

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700renegade

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My RV currently has a 40 amp Magnatech converter only.  I run my TV and Playstation with a cheap 400w msw inverter but the wire switching is a pain to go back and forth to use 120v shore power.

I can tell by the wiring and included old brochures that the RV was fitted with a Heart Interface 20 ( 2000 watt ) converter / inverter unit ( a subpanel for outlets and micro is looped via romex to a front basement cubby, abandoned heavy house batt cables extend along frame towards that cubby).  It has been removed somewhere in the past.

I bought a used Heart 10 for $100.  This would allow me to mothball my Magnatech (which I believe is a linear charger correct?), but I'd still have MSW inverter power, not full sine wave.  I've tried powering my microwave with my cheepy MSW to see if it will even light up ( it is an expensive touch panel whirlpool Velos model) and it does nothing - apparently it doesn't like the MSW.  Maybe the Heart MSW is better?

Am I better of to keep my Magnatech and just run a Xantrex Prosine 1800 ( I can get a used one for $350)?  I'll have plenty of clean sine wave power to run what I need (basically TV, DVD, PS2 and an occasional hot dog in the microwave).  I'll have more manual switching to do if I go this route.  I know there are new Xantrex solutions that will do it all, but I'm trying to keep this economical.
 
The Heart 10 is a 1000W inverter and isn't large enough to power your microwave.  Most microwaves will work on MSW but at reduced power.  You need at least a 1500W inverter to power one and even then it will draw your batteries down quickly.  We only use ours on inverter for a few minutes at most.  I would either get the Prosine or better yet, a Heart 20 as the wiring is already in place and it would handle your needs much better.

Very few appliances need pure sine wave power.
 
There is a graph on the Heart 10 that shows it can produce up to 1800 watts for up to 12 minutes.  I'm not interested in baking a turkey in it using the inverter, but it would be nice when I'm travelling for the wife and kids to zap a hot dog or something without having to start the genny.  Even if I can't use it off the inverter it's not a major problem for me.

The microwave I have can be set for lower power ( it actually trims power, doesn't just cycle 1500 w blasts like most do ) if needed.  Since it is on the subpanel that would be powered by the Heart 10 I'd like to know it isn't being mauled by the MSW.  It just sits there with a dark screen on it's LCD display and makes odd clicky noises when I plug it into the portable inverter I have now.  I wouldn't want to leave it plugged in that way for long.  I can only assume Heart might have a better waveform in it's unit than my $35 cheepy.
 
If it doesn't light up when plugged in and not cooking, then it doesn't like the MSW power.  We've had several Sharp microwave ovens and they all worked fine on MSW.  It sounds like the ProSine might be the better option for you.
 
Very few Microwaves will work on a 400 watt inverter.. Try 1500 or larger.

Xantrex Support

On the link above is an interesting document "Loads that may not work properly on a MSW inverter" if I recall the title properly.

No such document exists for TSW inverters.


You will need to trace the wires for that sub panel to figure out where to splice in the Heart inverter/converter.

And yes, it's better at battery charging than a Magnetek.  Most things are.
 
Just to be clear, I never tried to actually cook anything in the microwave with the 400 watt MSW inverter - my only reason to hook it up was to see if it would even light the display and show the time ( it did not ).  I would assume it would take only a handful of watts to accomplish that much.

There is no need to trace anything - it's all prewired from the old Heart 20.
 
Depends.. Though it does, in fact, only take a couple watts to light the dial... IT might take a thousand to power it up.. Just for a fraction of a second,  Depends on the microwave.

Now, the older micro's that I've torn down and replaced parts in.. They did not draw serious power till you hit COOK

But they cook differently on MSW.  SOME newer models have genuine power supplies.  And I suspect yours is one. These high voltage power supplies will draw maximum power when the unit is first plugged in, for 1/60 to 1/15th of a second usually.  but that's too much for the 400 watt box.

Don't matter if they are on or off, power setting does not matter.. They draw max power for a fraction of a second.
 
We'll I got a $100 used Heart Freedom 10 installed and it works fine for everything I've tried so far except the microwave.  The Whirlpool I have does work but is 'gitchy'.  It pauses and flickers the display when it is cooking - even if set at 50% power.  In addition it seems to cause the inverter to randomly kick out requiring a reset when it is plugged in - no cooking required.  It must cause some sort of feedback or load fluctuation that the inverter doesn't like.
 
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