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Homework Help: What is the real power of a generator

  1. Oct 12, 2011 #1
    I have problem after purchasing a Subaru 1700i inverter generator on ebay. The AC 240 doesn't work but the DC 12V works. It is written on the DC 12V "Only for battery charge"

    I tried to put a small inverter and a 230W halogen light directly on the battery + and - . The light started to work but suddenly the small inverter suposed to transform 12V into 240V start burning and was blow off.

    I have decided to buy a stronger invereter. I found one 1500W on ebay in Chine for only $50. I hope it will work.

    My question is: What is the power of my generator if using the DC12V exit. It is written on the generator 12V 8.3Amp. The generator is supposed to provide 1700W using the AC 240.
    Do you think it is a good idea to use the DC12 and add an inverter at the end ?
  2. jcsd
  3. Oct 12, 2011 #2


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    Staff: Mentor

    I would think you should return it to the seller for a refund, unless its description included "does not work". If the seller does not want to refund your money, notify ebay that the item did not work and ask for their advice. (They probably have a FAQ covering this.)

    12*9.3 = 99 watts (maximum)

    1700W relates to the AC outlet. The DC outlet is rated for only 99W.

    That is not an efficient way to obtain 240V. And it can never supply more than about 75W, because in practice the inverter loses some energy.
  4. Oct 12, 2011 #3
    Thanks for your answer. No Ebay return because it was said spare and repair No return.
    I really got it cheap for only $50 so not a such bad deal.

    If I plug a 240V inverter which will transform the 12V into 240V at the exit of the DC 12V.
    Is the 240V power still around 100 watt or could it be 240*8.3= around 1700 watts.
    I was thinking that it would be for each Volt 8.3Am/12V=around 0.7amp for each volt and therefore for 240V around 150W.
    I was dreaming it could be 8.3Amp * 240V but it seems that 8.3Amp is for 12V and not for each Volt.

    Anyway, I have found in the neighborhood a friend who know a mechanics who said it could be fixed for only $50.
    I have also purchased an 1500 watts inverter and will post here the result of my test. I will plug the inverter in the DC and switch on as many halogen bulbs as it could. This could be stupid but maybe the Amp will go up if more demand. I am only afraid to blow up my generator if using the DC 12V and not the recommend 240 V plug !!

    Do you think it is a risk for the generator to use the DC 12V with an inverter for running lights because it is written on the generator that the DC 12 should only be used for charging battery ?
    Last edited: Oct 12, 2011
  5. Oct 12, 2011 #4


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    Staff: Mentor


    If the damage was in the item before it was shipped, you may be able to get the cost of repair refunded by the seller. Email and ask first, before you post negative feedback.
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