Modified Sine Wave Inverter

snapnoodle
snapnoodle Registered Users Posts: 3
in Solar Beginners Corner #1
I read a lot about what a modified since wave inverter "cant" power.
So on that note what can it power without difficulties?

Lets say its 2000 watts
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
    Re: Modified Sine Wave Inverter

    The Watts isn't the problem; it's the waveform.

    MSW (Modified Square Wave to use correct terminology, which they don't when promoting them) should be fine with any type of resistive load such as incandescent lights. Any type of inductive load (transformers, motors) could be problematic. Much depends on the quality of the power supply involved as well as the quality of the inverter.

    And that's the trouble in a nutshell; it's a crap shoot, guessing game, other analogy of your choice indicating a chance. The inability to predict this in advance is why I don't recommend them at all.
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  • snapnoodle
    snapnoodle Registered Users Posts: 3
    #3
    Re: Modified Sine Wave Inverter

    for a chest freezer with one of those Johnson temperature controllers should I avoid this MSW inverter and stick to pure sine wave inverter?
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #4
    Re: Modified Sine Wave Inverter
    snapnoodle wrote: »
    for a chest freezer with one of those Johnson temperature controllers should I avoid this MSW inverter and stick to pure sine wave inverter?

    I would. Having run refrigeration off MSW I did not like the results; you could actually hear the motor clatter as it struggled to start on what looked to it like low Voltage.

    Things like laptops, on the other hand, would have no trouble with MSW because their power supplies are sophisticated enough to clean up just about any kind of input power.
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  • snapnoodle
    snapnoodle Registered Users Posts: 3
    #5
    Re: Modified Sine Wave Inverter

    right on cariboocoot,.....I appreciate your help
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  • Susido
    Susido Registered Users Posts: 32 ✭✭
    #6
    Re: Modified Sine Wave Inverter

    I wonder how many recommending against a MSW inverter have actually used a quality one for any length of time?

    I have used a Tripp-Lite MSW inverter for the past 6 years or so. I've used it to power just about everything electric I own that's within its capacity and that includes several computers, TVs, electronics of all kinds, a small fridge, small chargers and appliances, a great many tools. In all those years I have found exactly one thing my MSW inverter couldn't power; an electric blanket. Well I also discovered in a round-about way that a MSW inverter can't be used to charge another MSW inverter/charger.

    That said, it does seem like pure-sine wave inverters aren't as comparatively expensive as they once were. And they are slightly more efficient.
    Seasonally off-grid ... 468 Ahrs @ 48V (8 Rolls S-605 6v FLA batteries),  24 x 130watt panels, 6 x 260watt panels, 2 x Midnite Classic 150, Whizbang Jr., Magnum MS4448PAE inverter/charger, 2 x Honda eu2000i generators paralleled.


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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #7
    Re: Modified Sine Wave Inverter
    Susido wrote: »
    I wonder how many recommending against a MSW inverter have actually used a quality one for any length of time?

    I have used a Tripp-Lite MSW inverter for the past 6 years or so. I've used it to power just about everything electric I own that's within its capacity and that includes several computers, TVs, electronics of all kinds, a small fridge, small chargers and appliances, a great many tools. In all those years I have found exactly one thing my MSW inverter couldn't power; an electric blanket. Well I also discovered in a round-about way that a MSW inverter can't be used to charge another MSW inverter/charger.

    That said, it does seem like pure-sine wave inverters aren't as comparatively expensive as they once were. And they are slightly more efficient.

    I also used to use only MSW very successfully, and still have them ready to go with the flip of a couple of switches in case of failure of the newer Pure Sine inverters, but thankfully haven't had to use them for that. A little but very old and high quality 250 watt Prowatt powered all my CFL lights (didn't have LED lights back then), computer, TV etc with no problems, and a 1500 watt MSW was automatically via relay, powered up whenever the antique water pump (shown in every post) felt the need to run, and of course the old top load washing machine I then had. I didn't run the fridge or freezer on them except during emergency, as everything I've read indicated the compressors tend not to last as well. Vibrating coils and extra heat.
    The MSW did however smoke the power supply in a couple of breadmakers, and really overheated some parts in my Kill-A-Watt, so there's no way I'd risk my computerized front load washer on MSW. A $50 breadmaker is one thing, a $800 washer is quite another. Oh, and my rechargeable drills wouldn't properly charge.
    Now that I'm using PS inverters, all those worries are removed. For me, it's worth it to have PS.
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