Page 1 of 2 12 LastLast
Results 1 to 10 of 15

Thread: question about M2-atx kill switch

  1. #1
    Mo' Programming Mo' Problems
    Auto Apps:loading...
    Sonicxtacy02's Avatar
    Join Date
    Sep 2004
    Location
    Woodbridge, VA
    Posts
    8,168
    Blog Entries
    51

    question about M2-atx kill switch

    i wanna install a switch on the 12v constant line of the m2. the switch would kill all power to the m2 in the event the car is ever in for service etc. I found a perfect switch to match my console but the wire size for the switch is 24 ga. I have a 12ga goin from the battery to the m2 now. If i run the 12ga most of the way and just use a 1-2" length of 24ga just in and out of the switch will it degrade the power sent to the m2?
    mp3Car.com Senior Tech Blogger (Want a product reviewed? Contact me.)
    Find my plugins on the MP3Car App Store!
    Follow Me on Twitter or Facebook
    Live mp3Car Facebook Chat

  2. #2
    Constant Bitrate
    Join Date
    Nov 2005
    Posts
    202
    When I send the car in for service, I just pull the fuse at the battery.

    But to address your question: You should be all right as long as your switch is rated for the current draw of your system. The voltage drop should be neglible.

  3. #3
    Variable Bitrate nkotch's Avatar
    Join Date
    Dec 2005
    Location
    FL
    Posts
    412
    I wouldn't do that, even if just for 1" or so that 24ga wire will then be the "weak link" in the system and if there's ever a short of something that wire could catch on fire (or catch your car on fire) before the fuse blows. You could do a google search for amperage ratings for wire but I would probably guess that 24ga is "officially" rated for less than what you'd draw on 12v.

    You CAN however just use a relay and still use your switch, just wire your switch (w/ 24ga wire) and the 12V line to the relay. That way the switch isn't carrying the full load. http://www.the12volt.com/ has some good instructions on relays.
    Nick
    '99 Ford Escort ZX2 CarPC <-- RIP Feb '07

    2006 Chevy Equinox LS (Current Project)

    **VIA EPIA PD 1ghz Mobo, OPUS 150, 7" LinITX LCD touchscreen, 512 Ram, 60Gig HD, DLink Bluetooth, Belkin 802.11g wireless,

  4. #4
    Constant Bitrate
    Join Date
    Nov 2005
    Posts
    202
    From what I can find from google, for high-voltage applications the recommended (guidelines) carrying capacity for 24AWG is only ~0.5A for power applications and ~2.5A for chassis wiring with the fusing current at ~30A.

    Then again those figures are extremely conservative for 12v - which is hardly high voltage. The same tables have 18AWG (supplied with the M2-ATX) having a high-voltage carrying capacity of ~2.3A.

    You will have to weigh the advantages of additional protection of using a relay versus the disadvantage of complexity.

  5. #5
    VENDOR - ITuner/MiniBox
    Join Date
    Nov 2003
    Posts
    112
    My main worry with a switch is the reliability of the switch itself, the wire itself is very predictible in terms of power drops. AWG 24 is a bit of a stretch, but automotive PSUs tend to have a wide V(In) range...

    Despite wide V(IN) you should also must be able to sustain high input currents (Irip at 3000-ish Khz), the input capacitors on a PSU should take care of that.

    -Never use a switch at the input, if possible. If you must, use a higher current switch. I would rather use the "hybernate" option, consumes only few miliamps, your battery will last for several months or more!
    -Always use good crimping and moderate AWG wiring (AWG 10-ish is overkill for low power PSUs, AWG24 is on the low side, if more than few feet long).
    -Never use diodes or self-resetable fuses at input. While the benefits are tempting, they have lowsy DCR.
    -Never use chassis ground as your main ground. You never know what will happen when you turn on the AC or roll down your window. Even looking in your car's read mirror can cause a ground loop. (just kidding).

    -Andrei

    Quote Originally Posted by Sonicxtacy02
    i wanna install a switch on the 12v constant line of the m2. the switch would kill all power to the m2 in the event the car is ever in for service etc. I found a perfect switch to match my console but the wire size for the switch is 24 ga. I have a 12ga goin from the battery to the m2 now. If i run the 12ga most of the way and just use a 1-2" length of 24ga just in and out of the switch will it degrade the power sent to the m2?

  6. #6
    Mo' Programming Mo' Problems
    Auto Apps:loading...
    Sonicxtacy02's Avatar
    Join Date
    Sep 2004
    Location
    Woodbridge, VA
    Posts
    8,168
    Blog Entries
    51
    I plan to use UV tested high voltage wire ( the same wire as the inverter wire on the lilliput. but i suppose rather than risking a short at the switch itself i'll just go with the idea of pulling the fuse at the battery. Dunno why i didnt think of that.
    mp3Car.com Senior Tech Blogger (Want a product reviewed? Contact me.)
    Find my plugins on the MP3Car App Store!
    Follow Me on Twitter or Facebook
    Live mp3Car Facebook Chat

  7. #7
    Variable Bitrate nkotch's Avatar
    Join Date
    Dec 2005
    Location
    FL
    Posts
    412
    andrewb: Hibernation doesn't use any power at all... (Standby does though)
    Nick
    '99 Ford Escort ZX2 CarPC <-- RIP Feb '07

    2006 Chevy Equinox LS (Current Project)

    **VIA EPIA PD 1ghz Mobo, OPUS 150, 7" LinITX LCD touchscreen, 512 Ram, 60Gig HD, DLink Bluetooth, Belkin 802.11g wireless,

  8. #8
    Maximum Bitrate JimmyFitz's Avatar
    Join Date
    Nov 2005
    Location
    Austin, Texas
    Posts
    735
    Quote Originally Posted by Sonicxtacy02
    i wanna install a switch on the 12v constant line of the m2. the switch would kill all power to the m2 in the event the car is ever in for service etc. I found a perfect switch to match my console but the wire size for the switch is 24 ga. I have a 12ga goin from the battery to the m2 now. If i run the 12ga most of the way and just use a 1-2" length of 24ga just in and out of the switch will it degrade the power sent to the m2?
    Why not install it in series with the ignition lead. It would still keep the PC off because the M2 would think the key is always off. Then your power supply line would not lose any integrity.
    ~Jimmy

  9. #9
    Constant Bitrate Legarcondemerde's Avatar
    Join Date
    Jul 2005
    Location
    The Biggest Little City
    Posts
    210
    If you want to completely cut the power, just use a standard SPDT relay controlled by the switch you want to use. Wire one side of the switch to ground, the other side to pin 85 of the relay. Pin 86 goes to a constant 12v source, 30 and 87 are the two sides of the cut power wire going to your PSU. There you have it, when the switch is engaged it will trip the relay, cutting power to your power supply.

  10. #10
    Constant Bitrate
    Join Date
    Nov 2005
    Posts
    202
    Quote Originally Posted by nkotch
    andrewb: Hibernation doesn't use any power at all... (Standby does though)
    Heh. But the M2-ATX does even with the PC in hibernation.
    Mine draws ~9mA on mine even with no load connected.

    Okay.. okay.. splitting hairs here..

Page 1 of 2 12 LastLast

Similar Threads

  1. HOLY CRAP.....this is insane
    By cadence117 in forum Off Topic
    Replies: 13
    Last Post: 06-17-2008, 06:37 PM
  2. Powerin the LCD with the M2 atx
    By luckyno in forum LCD/Display
    Replies: 2
    Last Post: 01-20-2006, 01:14 PM
  3. Power switch question
    By gambit32 in forum General Hardware Discussion
    Replies: 4
    Last Post: 12-12-2005, 07:24 PM
  4. Inverter Question XBOX RELATED Help B4 I kill myself
    By Porgieanne316 in forum Power Supplies
    Replies: 12
    Last Post: 07-26-2005, 09:51 AM
  5. Opus kill switch
    By naveedh in forum Power Supplies
    Replies: 14
    Last Post: 12-23-2004, 08:19 PM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •