1. Untitled Document

Modified or pure?

Discussion in 'MOTORHOME CHAT' started by Coolbeanz, Jun 20, 2013.

  1. Coolbeanz

    Coolbeanz Funster

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    East Bergholt
    I aim to buy a 1000w inverter and can see that pure sine wave inverters are much dearer than modified sine wave inverters so I am guessing the pure ones are better but can someone tell me what is the difference and is it best to pay the extra?

    The main reason I need it is to power my low wattage travel hairdryer as it is clear from the forum that 12V hairdryers are only good for drying the back of stamps! :Smile:
  2. Snowbird

    Snowbird Funster

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    Liverpool.
    If you are only using a hair dryer than the modified will be fine.
  3. Coolbeanz

    Coolbeanz Funster

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    but if i have an inverter installed it seems logical it will be used for other things so do you know what kind of appliances need the pure as opposed to the modified? :BigGrin:
  4. vwalan

    vwalan Funster

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    i have been using a 2kw modified inverter in my trailer for about 8 yrs . never found anything that didnt work on it . unless they were really big power suckers . it went wrong the other day .i bought a cheap one from ebay . again does every thing it says on the box . fridge ,computer,telly ariel drills washing machine . . i think modified is ok . others say not but i find it ok
  5. pappajohn

    pappajohn Funster

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    scarborough, nth yorks
    modern electronics don't like modified sine wave of any source...Jennie or inverter.

    Laptops, TV,s etc can't be damaged.

    Now the tech bit in its most basic form:Doh:

    Draw a straight line on a piece of paper.
    Now draw a box on top of the line and another below the line but directly after the first....repeat along the line.

    This is a square wave form...electrically speaking, the 'dirtiest' form of electric....heating elements will work fine but usually not motors etc

    Next, draw what looks like a bicycle helmet then another below and upside down as in the square wave..

    This is a modified wave form.......cleaner than a square wave but not clean enough for electronics....heating appliances and some motors Will work fine

    Next draw a half circle in place of the box or helmet then as before.

    This is a pure wave form and everything likes a pure wave....same as your house electric.

    Incorrect waveforms can cause excessive heat to be generated in an appliance or motor.
    4 people like this.
  6. haganap

    haganap Funster

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    I accept what John says.

    However I have never had a problem, I have charged laptops iPads and everything else for 8 years +
    I've used all sorts of inverters cheap and expensive. :Smile:
    1 person likes this.
  7. Snowbird

    Snowbird Funster

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    Apr 24, 2009
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    Liverpool.
    I do have an inverter wired into the van. Its 2kw pure sine wave. I only use it for the microwave and hairdryer. Everything else is charged by 12 volt, laptops, tablet, phones and the TV are 12 volt.
  8. pappajohn

    pappajohn Funster

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    but do you use the appliances while being charged Paul ?

    Big difference between running a processor on an unclean power source and simply charging a battery on one.
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  9. haganap

    haganap Funster

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    John I have always used them whilst on charge over many years. I have had the kids in the back playing on laptops and watching films whilst I drive. There is nothing we haven't used, even the Xbox and sky box at some point.

    The inverter I'm using at present is a sterling 1800w modified sine wave inverter. If you read their explanation of pure v modified, they say it doesn't matter these days and give an explanation, of course they are selling the inverters, but we're happy :thumb:
    1 person likes this.
  10. pappajohn

    pappajohn Funster

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    Sterling is a well respected and recommended company who know their stuff so I would think their mod sine inverter will be a damned sight closer to pure wave than the cheap Chinese inverters.
    You get what you pay for :thumb:
  11. Jim

    Jim Ringleader Staff Member

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    Wales
    I've used modified for years charging and using laptops and tablets. Always plugged into a surge protector though. They work fine:thumb:
  12. vwalan

    vwalan Funster

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    i can only agree with paul. i have a laptop with a knacked battery i have to keep charging it all the time i use it . in fact i have two like it .both havent shown any fault yet.
    i understand what your saying ,but the only thing i have come across that doesnt like some inverters is a mates fridge . a small table top one . works a treat on a cheap chinese inverter bought in morocco for twenty quid . but plays up on some others . worked on my old ring inverter .
    all mine work a treat . i just bought an under-counter fridge freezer for the truck .but only bought it after testing it .
    i,m sure other things might be troublesome but havent really found it a prob. myself .
    john you have seen mine from ebay .it works and it was a cheap chinese . mind so was the ring inverter.
    Last edited: Jun 20, 2013
  13. pappajohn

    pappajohn Funster

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    never thought of that Jim :Doh:

    Mod and square are susceptible to spikes, which is probably what causes the damage, and that will obviously iliminate them :thumb:
  14. vwalan

    vwalan Funster

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    i do use one of them bought for a few quid in asda . maybe thats the secret.
  15. G8WVW

    G8WVW Funster

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    Cumbria
    600W modified sine-wave has been brilliant for all the usual electronics only problem is I've burnt out two Braun electric toothbrush chargers in 3-months. Coincidence? Never has one fail at home in 15-years.
  16. vwalan

    vwalan Funster

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    i think these days you can get manual tooth brushes . that stops that happening . hee hee
    yes i have heard of that problem . but my manual one is ok . :thumb:
    1 person likes this.
  17. pappajohn

    pappajohn Funster

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    I don't think coincidence....
    Some chargers, including on-board chargers on mod sine generators, don't get on with modified wave
  18. joner8888

    joner8888 Funster

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    I learn more on here, than i do all day listening to the radio:thumb:
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  19. Bailey58

    Bailey58 Funster

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    Norfolk and Toftir.
    My 2000w Ring MSW doesn't do my Senseo coffee machine at 1450w. Might eventually boil but gives up when the dispense button is pressed. Ok on the kettle which is only 900w, perhaps the Senseo is too sensitive? :Smile:

    Oh yes, having just returned from our France/Swiss trip I have to confess that the fuss about storing an extra gas bottle horizontally from 6 weeks or so back was unnecessary, we just about used the 6kg and never touched the 13kg let alone an extra one. :Doh:
    Last edited: Jun 21, 2013
  20. JeanLuc

    JeanLuc Funster

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    Warwickshire
    Thankfully I have never been asked to provide hairdryer power (yet) so we manage with just a 150W pure sine wave inverter to charge / run small appliances. I chose pure sine wave since the price premium was not too great for a small unit and wanted to ensure it would work on anything.
    I believe things like toothbrushes that use inductance charging, and anything with an induction motor might not like a modified sine wave. Also, I have read several reports of modified wave inverters 'frying' GHD Hair Straighteners, which, I understand, are rather costly items and often cherished by the lady owners.

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