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OBD Port Voltage

Discussion in 'Model S' started by 1NJ85D, Mar 16, 2016.

  1. 1NJ85D

    1NJ85D Member

    Joined:
    Feb 26, 2015
    Messages:
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    Location:
    Scotch Plains, NJ
    Is the voltage on the OBD port a reasonably stable 12V or does it fluctuate materially (like in an ICE battery)?

    I want to use it to power an electronic device and need to determine if I need to stabilize it.

    Thanks!
     
  2. Dithermaster

    Dithermaster Member

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    Dec 27, 2015
    Messages:
    181
    Location:
    Madison, WI
    I do not know the definitive answer but I assume it's just connected to the 12V battery, which is going to fluctuate. There would be no reason to have a special regulated 12V supply just for the ODB port.
     
  3. 4SUPER9

    4SUPER9 Active Member

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    Location:
    California
    I have used the OBD II port to power a dashcam for 2 years, and now using it to power a radar detector. I have never had an issue. Actually, I am planning to run a USB port from it for rear charging (with appropriate step-down to 5v)
     
  4. Tree95

    Tree95 Member

    Joined:
    Oct 24, 2014
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    Location:
    Usa
    It's connected to the car's 12v lead acid battery. The voltage goes up and down with load; it discharges to 50% multiple times per day before the big battery contactors close to run an inverter to recharge it. When parked and the big battery contactors are not engaged, the voltage will go up and down with load (lights, seat heaters) just like any car.

    What electronic device do you plan to use? Make sure you check your manual for the fuse rating on the odb port.
     
  5. garygid

    garygid Member

    Joined:
    Aug 11, 2014
    Messages:
    612
    Location:
    Laguna Hills, Orange County, CA
    Just like an ICE battery, it is called "12 volt" but it might be as high
    as 14.5 to perhaps 14.9 volts during charging and normal operation,
    and might go down to something like 11 volts when the car is off and
    the car's DC-to-DC system is not charging the "12v" battery ... which
    happens several times a day, for around an hour each time.

    So, unless your DC device is rated for about 10 to 15 volt operation,
    it is likely that you should take appropriate precautions.
     

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