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The on/off of the 12V outlet

Discussion in 'Roadster: Technical' started by Slackjaw, Mar 27, 2015.

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  1. Slackjaw

    Slackjaw Member

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    Short version: Anyone got accurate information on when the 12V outlet is on/off on a Roadster 2.5? Can it be forced to stay on using a service code or something?

    Long version: I've been using a dash cam for a while (more than a year). It works fine and runs from the 12V ("cigarette lighter") outlet. It now keeps resetting and/or forgetting the time and config. I think this is to do with the 12V outlet powering down when the car is locked or closed, and the camera battery dies before the 12V comes back. But it's not quite so simple - sometimes the camera resets, but sometimes it doesn't. It has definitely reset while the car was plugged in but not charging. It almost never resets when parked outside (locked, not plugged in) at work. In a recent service visit the car was indoors and I assume unlocked the whole time, and the camera ran constantly - I know this because it filled the 32 GB memory card with 2 days of footage which is about right for this camera. In my own garage under similar conditions it seems to forget its settings and power down a lot more often. I am currently recording the conditions each time I leave the car and trying to see if there's a pattern, because I had a gut feeling it was related to the SOC.

    If I can't come up with a clear set of rules my next experiment will be to use an automated text message (via an email-to-SMS gateway) to wake the car up via OVMS every hour, or 15 mins, or whatever.

    Thanks in advance,
    Ian
     
  2. Doug_G

    Doug_G Lead Moderator

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    The 12V stays on as long as the battery coolant circulation pump is running. If the battery pack cools enough that the pump can shut down, the 12V outlet shuts down too.
     
  3. markwj

    markwj Moderator, Asia Pacific

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    So long as car is closed-up, not charging, and battery is cool enough, approximately five minutes after last activity the car will go to sleep. The little coolant circulation pump will stop and 12V "cigarette lighter" outlet will power down.

    Doing anything to wake up the car (charging, open door, unlock, charge port, touch VDS, etc, etc) will wake it all up and keep it alive for another five minutes or so.
     
  4. Slackjaw

    Slackjaw Member

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    OK, thanks for the clear replies. My natural brute-force inclination to send keepalive wake-up messages via OVMS every 15 mins is probably not such a good idea in that it will massively increase the duty cycle of that coolant pump. But at least I understand the issue now. Probably better to buy a better camera (which doesn't factory reset so often) if I can't reduce the power usage of the camera to a point where it limps to the next charging opportunity.
     
  5. JohnGarziglia

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    Reston, Virginia
    I do not know if this will help but the one circuit I found which stays on all the time is the circuit in the fuse box for the alarm. Just put an "add-a-fuse" tap on it with an additional fuse if you want

    Another thing to try if you tap it so it gets continuous power is a battery discharge prevention device for a dash cam like the BlackVue Power Magic Pro: BlackVue - Full HD 1080p Dash Cameras with GPS.
     
  6. wycolo

    wycolo Active Member

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    Or just carry a 15ah agm battery around which weighs 14 pounds. Handy for all kinds of things.
    --
     

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