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Thread: Power: Inverter, Switch, battery connection

  1. #1
    Variable Bitrate
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    Apr 2002
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    Charlotte, NC
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    315

    Power: Inverter, Switch, battery connection

    Here's the deal. My cig lighter socket gets no juice unless the ignition is in the "acc" position, so it's kind of hard to leave the computer on if I just want to run in to pay for gas or something. So I'm thinking of connecting the inverter (300w) directly to the battery. What gauge wire should I use? And if I chop the cig plug off the inverter, how do I know which wire connects to + and which is ground or negative or whatever? I don't have a multimeter.

    Also, should I buy a Optima Yellow Top (deep cycle) battery for this, or is my stock battery fine?

    It's a 1999.5 Nissan Pathfinder SE. Is there any way that I could rewire it so the lighter socket always gets power? I would much rather do this than chop up my inverter. Then I was thinking that I could just put a switch on the + wire to turn it on and off (computer is set to auto-on when it gets a current in the BIOS).

    Also, what's the volts, amps, etc to a lighter socket?

    Need these answered too:

    ok, stupid question: The fuse goes on the positive wire right?
    Another very stupid question: Does the other wire go to the negative terminal or ground on the car body?

    A not quite so stupid question: To avoid any 'buzzing', I just run a wire from the casing of my PSU to the case, and from the case to the cody body?

    As you can see, my expertise is in computers, not electronics, or even basic circuitry
    Silver 1999 Nissan Pathfinder!
    Completion: [*********-] 90%
    Everything working! Mobile MP3s ROCK!
    LEFT TO DO: Improve power on circuit, fix slow boot time

    - 550mhz PIII on Abit BH6
    - 128MB RAM
    - 40x4 Backlit Character LCD
    - 17 key numeric keypad - Repainted buttons
    - 2.1GB laptop drive for OS
    - 4.3GB drive for MP3s

    http://www.mp3car.com/usersites/bombboyer/ Redesigned, new pics!

  2. #2
    Banned
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    Jun 2001
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    Adelaide, Australia
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    687
    Not sure what gauge wire you should use, but 25amps should be enough, 8gauge is rated at over 50amps, so, that is probably an overkill... The wire that connects to the centre pin of the ciraret lighter plug is positive, the wire may aslo have a line on it, or be coloured red... Your existing battery should be fine... The volta to a cig lighter socket is normally about .5 or less volts less that the battery voltage due to losses in teh wire/fuse. this is 8-14volts or whatever.... The amps would normally be 10-30 probably, it has a fuse, read it and see what it is...
    2 week temp ban (spam and complaining about deleted posts)
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  3. #3
    Constant Bitrate
    Join Date
    Jul 2002
    Location
    Los Angeles
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    156
    Use 8-10gauge wire. Put a 20-30amp fuse within 6inches of the battery + terminal. Be careful though with the inverter as it draws a lot more power than you would think. Leaving it to run off the battery rather than alternator may not be a good idea; a couple hours and your battery will be dead

    Thanks,
    Jad

  4. #4
    Variable Bitrate
    Join Date
    Apr 2002
    Location
    Charlotte, NC
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    315
    Any idea of how to rewire so the cig lighter always gets power? Can I just reroute the wires from the back of the socket to the battery terminals? Or do you think the car will have a problem with that.
    Silver 1999 Nissan Pathfinder!
    Completion: [*********-] 90%
    Everything working! Mobile MP3s ROCK!
    LEFT TO DO: Improve power on circuit, fix slow boot time

    - 550mhz PIII on Abit BH6
    - 128MB RAM
    - 40x4 Backlit Character LCD
    - 17 key numeric keypad - Repainted buttons
    - 2.1GB laptop drive for OS
    - 4.3GB drive for MP3s

    http://www.mp3car.com/usersites/bombboyer/ Redesigned, new pics!

  5. #5
    Variable Bitrate mp3hombre's Avatar
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    Aug 2002
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    Montreal / Los Angeles
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    266
    Yes it can be done but I'd rather wire the inverter directly to the battery. Many members have reported problems when using the cig lighter socket

  6. #6
    Low Bitrate
    Join Date
    Jul 2002
    Posts
    82
    If you are concerned about chopping off the plug then just buy a cigarette lighter socket and put it in a plastic box. Wire into the back of this through a fuse and then to the battery, as others have described in this thread.
    Best regards,
    Matthew

  7. #7
    Maximum Bitrate albysure's Avatar
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    Dec 2000
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    pittsfield, ma.
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    685
    i've been wondering the fuse question for awhile myself. i will be wiring up my keypower supply and will measure the amp draw with all my stuff running. i was in touch with the keypower tech in ca a few weeks ago and he said he didn't know what size fuse to use. right now i a have a 20a in there.
    i'll report back soon on what i measure

  8. #8
    Variable Bitrate
    Join Date
    Apr 2002
    Location
    Charlotte, NC
    Posts
    315
    ok, stupid question: The fuse goes on the positive wire right?
    Another very stupid question: Does the other wire go to the negative terminal or ground on the car body?

    A not quite so stupid question: To avoid any 'buzzing', I just run a wire from the casing of my PSU to the case, and from the case to the cody body?

    As you can see, my expertise is in computers, not electronics, or even basic circuitry

    Thanks for the help.
    Silver 1999 Nissan Pathfinder!
    Completion: [*********-] 90%
    Everything working! Mobile MP3s ROCK!
    LEFT TO DO: Improve power on circuit, fix slow boot time

    - 550mhz PIII on Abit BH6
    - 128MB RAM
    - 40x4 Backlit Character LCD
    - 17 key numeric keypad - Repainted buttons
    - 2.1GB laptop drive for OS
    - 4.3GB drive for MP3s

    http://www.mp3car.com/usersites/bombboyer/ Redesigned, new pics!

  9. #9
    FLAC MP3DUB's Avatar
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    Jan 2002
    Location
    Chicagoland, IL
    Posts
    1,782
    The fuse needs to go within the first 8? inches of the wire run from the battery on the positive wire. The ground just needs to go to the body, anywhere you can get a good (no paint, bare metal) ground. A self tapping screw works well for this. And grounding the case of the computer to the same spot helps with noise in the system.
    -Nick

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