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Thread: Inverters and power drawn

  1. #1
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    Inverters and power drawn

    Let's say my carpc draws a constant current of 200W. Is a 500W inverter draw more power from my alternator than let's say a 300W one.

  2. #2
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    Yes or No would do it....thanks

  3. #3
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    I could be wrong here, but I'm going to bet that that inverter isn't going to put out it's max wattage rating at all times....just like a regular amplifier....it has the capability of putting out a MAXIMUM of 500 watts. If you are only demanding 300 watts from it then it will only supply 300 watts.

    Make sense?
    Jan Bennett
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  4. #4
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    As red says, input is proportional to load.

    EDIT: oops, composing replies in word as i am in work and pasted two answers so deleted it before anyone asks!

  5. #5
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    Correct. draw = (load) + (no load draw)
    No load draw is a constant. It's pretty low for most inverters but will still kill your battery over a week or so.

  6. #6
    Maximum Bitrate mushin's Avatar
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    Mm, to be a little nitpicky, not exactly. The inverter will likely have a non-flat efficiency curve over power draw. So it may, for example, be 60% efficient at 50% load, and 70% efficient at 100% load. I doubt it'll make much difference, but I would expect a little difference.

  7. #7
    Maximum Bitrate mushin's Avatar
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    Quote Originally Posted by Red GTi VR6
    I could be wrong here, but I'm going to bet that that inverter isn't going to put out it's max wattage rating at all times....just like a regular amplifier....it has the capability of putting out a MAXIMUM of 500 watts. If you are only demanding 300 watts from it then it will only supply 300 watts.

    Make sense?
    You're absolutely right that a 500 watt amp will only supply 300 watts to a 300 watt demand, but it will draw more than 300 watts. Class A amps are particularly horrible in this sense, as their efficiency plumments at lower outputs (they basically bleed off the extra power). Class A/B is a bit better, but not exactly great. Class D is the exception, being switched.

  8. #8
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    well, that is correct, but isn't that going a little overboard when trying to explain the answer to this guy?
    Jan Bennett
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    Please post on the forums! Chances are, someone else has or will have the same questions as you!

  9. #9
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    thanks, thanks, thanks....

    just have to find a class d inverter

  10. #10
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    Quote Originally Posted by Red GTi VR6
    well, that is correct, but isn't that going a little overboard when trying to explain the answer to this guy?
    My thoughts exactly. LOL. This is a newbie forum after all.

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