Modified sine VS Pure sine

Discussion in 'Off Grid' started by rhino, Apr 28, 2012.

  1. rhino

    rhino WindyNation Engineer

    Looking into getting a back up power inverter. But I am very confused on the semi modified / modified sine and the pure sine. I get it that pure sine is what I get from the power company. Will the modified sine run my house? Or will It only run certain things. I see a stackable semi modified sine inverter from sun that looks cool. You can start with just one unit and add more and they will act as one. http://www.ebay.com/itm/2500W-5000W-Stackable-Power-Inverter-48V-DC-TO-230V-AC-/350525811185?pt=LH_DefaultDomain_0&hash=item519cf769f1 Does anyone have these? My plan is to start small and work up to being able to power my whole house.
     
  2. Minnesota

    Minnesota WindyNation Engineer

    Any appliance with a motor will either work poorly, not work at all, or will have a shortened life if attached to anything but a pure sine wave source. We are taking refridgerators, furnace blowers, fans, hair dryers, drills, vacuum cleaners, blenders, ... . Most home electronics have a front-end transformer to reduce the 120Vac to a lower voltage, and these can overheat if the input waveform is not pure sine. I'm sure many things work with a modified sine unit but I personally would be careful with what I plug into them.
     
  3. rhino

    rhino WindyNation Engineer

    Do you have any recommendations for a pure sine inverter for a 48v battery bank? Hopefully one that does not break the bank.
     
  4. Minnesota

    Minnesota WindyNation Engineer

    I really don't. I got an 800w one for under $100 (used). It was used on a Sprint vehicle so it is rugged as hell. Xantrex, Magnum Energy, and Outback are the premier brands.
     
  5. I may have 2 cents worth of education to share on inverters. Saving a buck just to get an inverter to run the fridge or TV ET is a rush, and I understand the excitement. I started out with a 12 volt square wave. Then I spent a few bucks on a Go Power 2000 watt sine wave inverter. http://www.gpelectric.com/
    Nice unit, it powered the washers, gas dryer, one deep freezer and two refrigerators and lots of other small loads. Last August the hum stopped, and a brown stinky juice was dripping from the inverter. The caps popped. My emails to the place I purchased it from were ignored. After rereading the fine print on the manual, the unit isn’t repairable. That seems to be common these days with the imports. I assumed this inverter was made in Canada. No schematic available either.
    This is a trustworthy place where I spend my hard earned cash. I asked, but they won’t sell me any Junk. This is what I purchased http://www.solar-electric.com/exxp24vol11w.html . Yeah, I choked on the price, whined a little, and then I was kindly reminded I had already cheaped out before because of the price, and I could have bought the 2000 watt Exceltech with the money from the No Power I have. I have deliberately overloaded the Exceltech and it cuts back to 60 volts AC until the overload is removed.
    Another lesson I learned, The No Power input voltage was 30 volts max for a 24 volt battery pack. My deep cycles charge at that voltage…..maybe that was the problem. Exceltech will take up to 33 volts. Look at the idle power usage. Watts add up, so I spent another 40 dollars to have the 10 watt idle standby installed. So the question is what now..? How much can I spend?
     

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