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  1. #1
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    using a power inverter in a car

    I just bought a DeWalt 1000 W power inverter to power my laptop and 8" monitor for my 'carputer'. The 8" monitor is in the dash and shows the windows screen on the laptop. It works just fine when the engine is off, but starts beeping and showing a 'voltage too high' error when the engine is running because the alternator is charging the battery at 14-15vdc. Is there any kind of 12v DC-DC converter or zener diode I could use to clamp the voltage to the inverter to 12vdc?

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    Re: using a power inverter in a car

    Not really. The 14-15V is being regulated by the alternator and it isn't going to like it's output being 'shorted' to 12V across a zener. Plus the zener will melt.

    I think you have a malfunctioning inverter since any decent automotive electronics should run properly at 14-15V.


    On a quick look I found a similar inverter specified to 15V. Maybe you really have 15V and its tripping....

    In the marine world I've seen people throw in rectifier diodes to get the 0.7V drop. That might work here but 1000W at 12V is 80A. It needs to be a huge rectifier diode to handle that.



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  3. #3
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    Re: using a power inverter in a car

    This is the 3rd inverter I've bought and they all did the same thing. It just occurred to me that all I have to do is to use a 2nd battery, not connected to the alternator. Then I guess I could just charge it up with a battery charger once in a while or maybe I could use a battery isolater. Not quite sure how they work, I'll have to do some research.



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    Re: using a power inverter in a car

    If the inverter still works when it beeps and warns, the simplest solution is to remove the warning buzzer.
    If the inverter is destroyed because of 14-15V supply, it is junk anyway.



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    Re: using a power inverter in a car

    Notebook and monitor are likely having low voltage DC power supply, e.g. 15 to 19V. They can be better supplied with a small boost DC converter (in case they don't even work with 12V input) than an inverter.



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    Re: using a power inverter in a car

    I have not seen inverters complain about high input voltage,
    but have seen them act very badly at undervoltage. Fried a
    serial port on a tuning laptop when the inverter powering it,
    went into flickering undervoltage cutout. Definitely a bad
    idea to connect the PC to the vehicle "ground" as the ground
    loops are likely large and poor quality / high risk.



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    Re: using a power inverter in a car

    Quote Originally Posted by std_match View Post
    If the inverter still works when it beeps and warns, the simplest solution is to remove the warning buzzer.
    If the inverter is destroyed because of 14-15V supply, it is junk anyway.
    The problem with that is the 110v output shuts off when it goes into a fault condition.



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