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Aftermarket Sub-woofer Amplifier Installation using DC-DC +12v Power Source

Discussion in 'Model 3: Interior & Exterior' started by Jamie Sibley, Apr 18, 2019.

  1. marcmerlin

    marcmerlin Member

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    Thanks. It's a long document, what part was what actually helped?
    I'd think that if you disconnect 12V from both sides (battery and DC-DC side), the car should fully lose power and forget the old battery. Are you sure that it's not enough?
     
  2. marcmerlin

    marcmerlin Member

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    Interesting, I didn't think about those, but I am dealing with 200A, I'm not sure a few of those, even in parallel, are going to do the trick. (3000W inverter at 12V is actually 250A)
    Other people who worked on this talked about a bypass relay once the inrush is over, and honestly you need a solid piece of copper for 200A, so I'm not sure there is any way around that.
     
  3. 9-Volt

    9-Volt Member

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    All of the (13) steps outlined to disconnect the high voltage power, and then the reverse to reconnect the high voltage (and 12V), were required.

    Sorry, I thought you'd already tried disconnecting the 12V and it didn't work. The guys in the shop fully disconnected the battery for 24 hours and it still wasn't enough to make the car think a new battery was being hooked up. Worked instantly after following the steps above, and no problems since, so I think the key is a disconnect/connect of the high voltage.
     
  4. marcmerlin

    marcmerlin Member

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    Did you disconnect the 12V from both sides? If you only disconnect the battery, the DC-DC will keep the car alive from the other side.
    If the DC-DC trips, or you disconnect it from under the rear seat, and then you also disconnect the battery, the car's computers have no power and absolutely nothing will work, including opening doors (so don't close the trunk unless you want to try the emergency opening procedure).
     
  5. 9-Volt

    9-Volt Member

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    Not 100% sure, as my audio shop did it, but I think they had the battery out of the car and sitting on a charger. I know they also tried disconnecting the power from under the rear seat (but not sure if the battery was disconnected at that point or not).

    Obviously, your mileage may vary as to whether some or all of the steps outlined in the Tesla document linked above are required to clear the 12V error message. I just thought I'd pass along the info that worked for me--as food for thought--in case you can't clear the message and have a known good battery.
     
  6. marcmerlin

    marcmerlin Member

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    To close off that discussion on this thread too, please go to How many amps can you get from the 12V system for emergency situations? for how I made it work.
    I now have a 2000W inverter that powers on and off at the same time than the car DC-DC system, without the big current inrush that was disabling the car's DC-DC system in a way that it didn't really reset on its own.
    Turns out I didn't even need a zener diode, relying on the voltage being high enough at the inverter poles to trigger a bypass relay, was enough.
     
    • Informative x 1
  7. Ravire

    Ravire Member

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    So forgive me if I’m wrong but in newer model 3s there’s a trailer wiring harness behind the rear bumper can the 12v on this be used as a remote turn on? I believe it leads to vc_left and I have no interest in using a trailer so it would cut down on the amount of work.
     
  8. marcmerlin

    marcmerlin Member

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    do you know what fuse it's connected to? how many amps? by connecting to the DC-DC under the rear seats, you get 200A :)

    Marc's Blog: electronics - Using a Tesla Model 3 as Emergency Power Source In Case of Grid Failure
     
  9. Idkorcare

    Idkorcare Member

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    Vc left no longer functions the same way as it did before with one of the last updates, it currently mirrors the dc-dc power and only shuts off when the car sleeps, no clue on the wiring behind the bumper, id check the factory sub first.
     
  10. Ravire

    Ravire Member

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    Oh okay I’ll just use the signal turn on then
     
  11. Ravire

    Ravire Member

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  12. Idkorcare

    Idkorcare Member

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    Fwiw straight up signal sense MIGHT also keep the amps on longer than expected. I was using signal sense when the update to vcleft changes how it worked and notices the amps would stay on even tho no audio was playing like while sentry is on or the penthouse is still awake.

    i ended up running a relay off the console lights to get a new turn on but others had trouble getting it to work.
     
  13. Ravire

    Ravire Member

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    Do the amps staying on longer just hurt range or will it cause any errors due to the power draw. I don’t mind losing a little range while I’m out of the car.
     
  14. Idkorcare

    Idkorcare Member

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    you probably wont notice it affecting range, they will just be on. I set off warnings on my car way more than I want to admit installing the stereo testing different things and im pretty sure 95% of the battery errors people were having were caused by running accessories directly off the 12v and letting the car sit, running the battery down just enough(right around 12.0v) that the car thought it was bad and made no attempt at charging it as a precaution.

    I also hooked my amps up directly off the 12v battery and it never tossed an error from drawing power off it. But what would happen is once I crossed some current draw threshold, and im talking cranking up the stereo to near full blast for a bit, it would stop charging the 12v battery till I lowered the load.
     
  15. Ravire

    Ravire Member

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    Okay I’ll keep an eye out I’m installing it tomorrow so we’ll see how it goes
     

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