TMC is an independent, primarily volunteer organization that relies on ad revenue to cover its operating costs. Please consider whitelisting TMC on your ad blocker or making a Paypal contribution here: paypal.me/SupportTMC

Jumping 12V Battery via Power Port

Discussion in 'Model S: Battery & Charging' started by omarsultan, Oct 3, 2013.

  1. omarsultan

    omarsultan Active Member

    Joined:
    Jun 22, 2013
    Messages:
    1,496
    Location:
    Northern California
    Does anyone know if the 12V battery in the Model S can be jumped via those chargers that connect via the cigarette lighter?

    Omar
     
  2. EdA

    EdA Model S P-2540

    Joined:
    Mar 24, 2011
    Messages:
    1,882
    Location:
    Massachusetts
    Call your local service center!
     
  3. ChrisPDX

    ChrisPDX Member

    Joined:
    Mar 19, 2013
    Messages:
    158
    Location:
    Hillsboro, OR
    No. The power port is not directly connected to the battery. If the system is off, the port is disconnected from the battery. So if the battery was dead, putting 12v to that circuit would not do anything as it wouldn't make it back to the battery. You must jump the car via the jump posts behind the grill.
     
  4. omarsultan

    omarsultan Active Member

    Joined:
    Jun 22, 2013
    Messages:
    1,496
    Location:
    Northern California
    #4 omarsultan, Oct 3, 2013
    Last edited: Oct 3, 2013
    Perfect--that's exactly what I needed to know. My Tesla is fine, I just looking for something more wife-friendly then then whole nosecone and jumper cable routine.

    O
     
  5. brianman

    brianman Burrito Founder

    Joined:
    Nov 10, 2011
    Messages:
    15,487
    What about the USB ports?
     
  6. Doug_G

    Doug_G Lead Moderator

    Joined:
    Apr 2, 2010
    Messages:
    15,848
    Location:
    Ottawa, Canada
    Uh, those are supplied via a 5V regulator. Putting 12V in there is going to cause damage!
     
  7. omarsultan

    omarsultan Active Member

    Joined:
    Jun 22, 2013
    Messages:
    1,496
    Location:
    Northern California
    I think he was asking is the USB ports have juice if the car is off (for phone charging, etc.)
     
  8. brianman

    brianman Burrito Founder

    Joined:
    Nov 10, 2011
    Messages:
    15,487
    Well, no, that's not what I meant exactly...
    ... nor that.

    Let me try rephrasing:

    Given that the USB ports aren't switched off when the car is in "screens go black" mode, can they be used to trickle charge the car's 12V battery?

    I suspect the rate would be absurdly slow, if possible, but I'm curious nonetheless.
     
  9. islandbayy

    islandbayy Active Member

    Joined:
    Feb 25, 2013
    Messages:
    2,015
    Location:
    Greendale, Wisconsin
    I mentioned it in another thread, to charge through the USB port, at maximum rate they can safely handle, your looking at about 2 weeks to recharge the 12v, and prob 24 hrs to get enough power to turn the car on. Another issue is, if the battery is defective and not just dead, it could be "bleeding" off power (self discharging) quicker then you could charge through the USB. That, and going through usb, would also depend on the power circuit. A voltage regulator is converting 12v to 5v, and may not even be capable of shuttling that power backwards.
     
  10. Puyallup Bill

    Puyallup Bill Member

    Joined:
    Sep 7, 2012
    Messages:
    606
    Location:
    Puyallup WA
    I don't know what Tesla is using, but I'm not aware of a DC to DC circuit that can be used 'backwards'. Anyone?
     
  11. brianman

    brianman Burrito Founder

    Joined:
    Nov 10, 2011
    Messages:
    15,487
    How long to get enough power that the 17" will wake up long enough that you can open the charge port?

    (Yes, I've already recommended to Tesla -- months ago -- to add a physical switch to open the charge port.)
     
  12. umuhk

    umuhk Member

    Joined:
    Sep 17, 2013
    Messages:
    52
    Location:
    Pacific Northwest
    Doesn't the charge port open from pressure on the corner by the hinge?
     
  13. islandbayy

    islandbayy Active Member

    Joined:
    Feb 25, 2013
    Messages:
    2,015
    Location:
    Greendale, Wisconsin

    Charge port can be opened by prying it open slightly. Wont do any good though, without the 12v system "online", the car will not begin to charge (according to what I was told by Tesla).
     
  14. brianman

    brianman Burrito Founder

    Joined:
    Nov 10, 2011
    Messages:
    15,487
    Attempting to rephrase for clarity...

    Suppose your car goes completely unresponsive. Say 1% SOC and empty 12V. How long of USB port charging of the 12V would be required to wake up the 17" long enough to open and unlock the charge port and begin charging? For now let's assume you are "quick like a bunny" with connecting the Tesla end of your UMC (and that the other end was already plugged into a 14-50)?

    Until/unless they give us a physical alternative to nudge the process along, this (USB port) is the best option I've heard so far for waking up a dormant Tesla without moving it and without aid from another vehicle.
     
  15. Puyallup Bill

    Puyallup Bill Member

    Joined:
    Sep 7, 2012
    Messages:
    606
    Location:
    Puyallup WA
    Well, has it in fact been confirmed that you can use the USB port to charge the 12 volt battery? Or, use the USB port to otherwise wake up the car?
     
  16. brianman

    brianman Burrito Founder

    Joined:
    Nov 10, 2011
    Messages:
    15,487
    ".... if it works." :)
     
  17. Red

    Red Member

    Joined:
    Sep 27, 2013
    Messages:
    35
    Location:
    earth
    The lead acid battery has 12v nominal. USB is 5 volts.. You will not be charging it from the USB unfortunately.
     
  18. islandbayy

    islandbayy Active Member

    Joined:
    Feb 25, 2013
    Messages:
    2,015
    Location:
    Greendale, Wisconsin
    Please, just do not do it. I forsee damaged electronics. The best way of waking the car up is by using the 12v terminals under the nose cone. Quick touch of jumper cables or a boost box is enough to wake the car up. The moment its woken, the DC-DC converter will kick in and start charging the 12v. I highly doubt the circuit for the USB ports could handle the reverse current. I For-See damaging the 12v-5v dc-dc converter in the USB Ports.
     
  19. Cottonwood

    Cottonwood Roadster#433, Model S#S37

    Joined:
    Feb 27, 2009
    Messages:
    5,062
    Location:
    Colorado
    This discussion is a fantasy anyway. When the 12V battery is dead, and the MS is in a deep-sleep mode, who really thinks the DC-DC converters that supply 5V for the USB ports will be up and running?
     

Share This Page