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Thread: Deals on inverters... Which one to get?

  1. #1
    Newbie
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    Bloomington, IN, USA
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    Deals on inverters... Which one to get?

    Hi all,

    I am not sure what kind of power supply to use. Being a relative novice when it comes to car electronics, I think that it sounds like a power inverter would be significantly easier than a DC converter.

    So, I was over at myfamily.com, which is running all sorts of coupon specials for at least a short while longer ($50 of $95, amongst others).

    I finally checked there for power inverters. I was pleasantly surprised that there were quite a few models there. Now, what I need to know is which one to try (price is an issue, but so is quality).

    Even if noone has specific knowledge with these models, I would love to know anything about what specs to look for. Will I have to somewhat match my computer's power supply with the inverter's peak or something? Is the low battery shutdown or warning a good idea? It sounds like a good idea, but I don't know if the execution is poor.

    Also, am I doomed to have some degree of bacground noise from one of these things no matter what? Thanks much.

  2. #2
    Constant Bitrate
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    CA
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    I know that one major disadvantage is that you won't be able to turn your engine off and on again without the computer re-booting, since the inverter requires so much voltage.

  3. #3
    Newbie
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    renton, wa, usa
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    now, I'm not an Electrical Engineer, but couldn't you work around that reboot issue with a capaciter hooked up before the inverter?

  4. #4
    Newbie
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    Yeah, that is a disadvantage, but I can definitely deal with that. I am more concerned about which are better, assuming that I will try one of them. Any thought anyone? Please?

  5. #5
    Variable Bitrate
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    A capacitor won't do much -- the voltage from the car battery can sag below 9V while cranking. Once the engine has started, the alternator will kick in and drive the voltage up aroun 14V, which is fine for an inverter. A capacitor is used for car audio to give the amp the extra current it needs during deep bass hits and such. Comparing the demand of an amp to the starter of your car, it takes at least a second or so to start the car, I don't think a capacitor will help.

    Plus there is the danger of back EMF from the starter's coils working its way into your computer -- if this happens, it could fry your motherboard and/or power supply. This is why most car-powered devices have warnings about leaving them connected while starting the car. This is also why in many cars the radio and other accessories don't work while the starter is cranking -- they are bypassed until the key is moved from "start" to "on".

    DC-DC power supplies aren't as sensitive to power sags as an inverter + PC power supply are because they can operate down to near 8V to begin with; most inverters will begin to have problems around 11V.


    --Jason
    www.m2pc.com
    Jason Johnson
    Yorba Linda, California
    http://www.m2pc.com

    MPC Phase IV - *** PENDING ***

  6. #6
    Variable Bitrate
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    Back on topic with this thread -- most people have found the cheap, "on-sale" inverters at FRY's and other stores to work just fine. I bought a LinkSys 140W inverter from FRY's for my first in-car PC and it didn't have any problems -- except the computer would hang/reboot when I tried starting the car with it running

    You don't need to go out and buy a 300W inverter just because your power supply says "250W" on the case; chances are your computer only draws around 100W max (when I had an inverter on mine, it was only drawing about 50W). A good thing to remember with the ratings on power supplies is they always state the "maximum available" when they give an amperage or wattage rating. The normal draw is usually be much less.



    --Jason
    http://www.m2pc.com
    Jason Johnson
    Yorba Linda, California
    http://www.m2pc.com

    MPC Phase IV - *** PENDING ***

  7. #7
    FLAC Gutter's Avatar
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    Dec 1999
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    Casina, Italy
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    I bought a 300w Tripp-lite inverter for $30 from a friend who works at Best Buy. That's how much it costs him with his discount. Damark sells a 300w for $50 that I hear is pretty decent.

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