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How much power from 12 V power outlet?

Discussion in 'Model S: Battery & Charging' started by linaser, Apr 18, 2012.

  1. linaser

    linaser Member

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    According to the Model S Specs and Standard Features | Tesla Motors webpage, the Model S will have a 12 V power outlet.

    Now I'm wondering how much power you can draw from this outlet.

    To charge my laptop computer and use it at the same time, I would require about 100watts.

    But I'm also thinking about buying a 12V to 230V inverter, so I could use a couple of other devices.

    Does anybody know more about this?
     
  2. VolkerP

    VolkerP EU Model S P-37

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    You might check the Roadster threads on 12 DC accessories and inverters.
    The Roadster (2.0) Owner's Manual says:
    12 volt accessories?
    Inverter alternative for Teslas
    One Roadster was damaged by using an inverter, Tesla claimed that line noise destroyed some 12V circuitry and initially it looked like the customer had to bear the cost (they changed their mind afterwards and handled it under warranty)
    WARNING: Do not plug an AC inverter into your 12VDC socket!!
     
  3. linaser

    linaser Member

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    #3 linaser, Apr 18, 2012
    Last edited: Apr 18, 2012
    Thanks for the links to these threads.

    When I read them, I see many people, who are very unsure, what accessories are save to plug in and which are not (because they use switching power supplys as an inverter does).

    I think this is something that has to be addressed in the Model S, so that we will be able to use the 12V power outlet like on any other (ICE) car.

    Or as pointed out by somebody in that thread, Tesla would have to prohibit the usage of the outlet generally, because you can't expect an average person to know the difference. But that would not make any sense, because they advertise this feature on the specs page.

    So I'm with doug, who wrote in the other thread:
    I hope, that Tesla will implement the 12V power outlet in a way, that the Model S can't be harmed no mater what kind of 12V accessory is pluged into it.

    But is there actually anything known about how this will be in the Model S?
     
  4. zdre

    zdre 40kWh Model S P6415

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    Correct me if I'm wrong, but I'm pretty sure that Model S has a regular 12V Lead-acid battery (which Roadster does not), which should buffer most noise from an inverter.
     
  5. Roadster does have a lead acid battery, it is located underneath the passenger side headlight. This battery is uses for the cabin electronics.
     
  6. Doug_G

    Doug_G Lead Moderator

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    The Roadster's battery is a small sealed lead-acid battery used for backup power if the ESS goes offline. It keeps the headlights and wipers working until you can pull over. It's normally not used.

    The Model S has a full-size lead-acid car battery. I'm sure it will handle all the same accessories as "ordinary" cars.
     
  7. Iz

    Iz EVs are here to stay

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    The majority of Model S owners will be quite knowledgeable. However, there may be that small segment that will attempt to "jump" a dead battery pack from the lead-acid battery.
     
  8. Lloyd

    Lloyd Active Member

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    So if the Model S has a full size lead acid battery, will it be allowed to give an ICE a "Jump Start"?
     
  9. Doug_G

    Doug_G Lead Moderator

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    Could be possible... and in fact they may rarely need to be boosted themselves.

    At the auto show several EVs had to be jump started at the end. Their traction batteries were full but their lead acid batteries were flat from having the doors open and therefore the dome lights on all week. A booster pack got them up and running.
     
  10. I am pretty sure the ABS & SRS & VMS use that 12V battery and are not run off the ESS.
     
  11. Doug_G

    Doug_G Lead Moderator

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    I'm pretty sure those systems are backed up by that battery. In any case the primary power to keep that battery topped up comes from the ESS.
     
  12. Andrew Wolfe

    Andrew Wolfe Roadster 472 - S 440

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    Most cars have a 120W limit on the accessory 12V plug - the connector can't safely handle more than that.
     
  13. #13 smoothoperator, Apr 18, 2012
    Last edited by a moderator: Apr 18, 2012
    Yea that is pretty obvious that the 12v battery gets replinished by the ESS, the 12v battery serves a larger purpose than just being there for backup. It actively powers electronics in the cabin.


    I am referring to this, the 12V is indeed normally used.

    Check this thread out:

    12 volt accessories?

    Post 5

     
  14. Doug_G

    Doug_G Lead Moderator

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    Yes, but I expect the 12V battery is constantly fed power while the car is operating. So the power comes from the ESS. At most the 12V battery is acting like a (super)capacitor.

    We actually manufacture a motor control system that runs that way. It has a 12V sealed battery - identical to the one in the Roadster - that is essentially trickle charged all the time. It doesn't really provide power to the electronics except in two situations. If the mains power goes out, it provides emergency backup power, so everything can shut down safely. Also if the control system is hooked to a larger DC motor, the battery essentially acts as a capacitor and absorbs the motor startup surge.
     
  15. The ESS charges the Lead Acid battery when it falls under a certain threshold (not continously)... I know that certain electronics operate exclusively off the ESS, certain electronics operate exclusively off the 12v Lead Acid battery (regardless if ESS is "charging" the lead acid battery or not) and electronics that operate off both. Do you have any technical documents or logs (from Tesla or your Roadster) which corroborate your theory with regards to the ESS and 12v (that you claim is only used in emergency situations i.e. Failed ESS)? I am just curious because I have never heard of the 12v battery on the Roadster working in the fashion you describe.. Thanks!
     
  16. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    Hopefully Tesla will have a better 12V battery monitoring system than the Prius (or the Leaf from what I've read on the forums). The problem with the 12V battery is that because there is no starter motor, there is no warning when it starts to get weak. in the Prius this can cause odd behaviour and sometimes cause it to throw codes. In one case the Toyota dealer told the owner that they would need a new traction battery, new transaxle, and new inverter. Fortunately the owner posted this in one of the groups and followed the groups instructions to replace the 12V battery and see if the codes didn't go away. They did. On my 2004 at five years I replaced the battery and found that it had two dead cells. I never had to do a jumpstart nor was there any odd behaviour.
     
  17. TEG

    TEG TMC Moderator

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    Keep in mind that 1.5's seem to have a different arrangement for the aux 12v compared to 2.0 & 2.5's...

    For the 2.x's it is my understanding that the aux 12v battery is primarily there to keep things like the headlights and door locks working for a while if the ESS / DC->DC should stop providing power. This could be due to it failing, running out of charge, or being disconnected such as in an accident. If your ESS got damaged in an accident it might be good for the headlights and door unlocks to keep working - so, for instance, someone could see the car, and open the door to help you out.
     
  18. If you disconnect the lead acid 12v the door lock switch works, if you disconnect the ESS the door lock switch does not work....I know this much from my own personal experience (2011 Roadster)...

    Scott451 in this thread:
    12 volt accessories?

    Listed a comprehensive list of electronics that work off the ESS and ones that work off the Lead Acid battery. Quote below:



    Please advise?
     
  19. Doug_G

    Doug_G Lead Moderator

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    It could well be true; however, I don't believe every detail of technical information I get on the Roadster, because I have heard too many contradictory things from different people. So you might very well be correct. Or not.

    Scott has certainly dug further into the Roadster than any non-Tesla (uh, formerly non-Tesla) person I know of. But saying it "runs off the battery" might really mean "runs off the Vsb bus", and depending on how things work it might not draw primary power from the lead-acid battery.

    Basically I'm saying I'm not convinced either way at this point.
     
  20. MikeC

    MikeC Active Member

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    Any updates on this topic?

    Specifically, is it safe to use something like:

    Amazon.com: BESTEK 150w power inverter car dc 12v to 110v ac inverter dc adapter laptop charger notebook adapter dc charger ac adapter usb charger Dual USB 3.1A 1511C: Cell Phones Accessories
     

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