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Emergency battery booster?

Discussion in 'Model S: Battery & Charging' started by MrBoylan, Sep 12, 2013.

  1. MrBoylan

    MrBoylan Member

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    Just had a random thought the other day and was curious as to whether anyone (Tesla or aftermarket) have or are working on a portable emergency battery boost module for the Model S. I keep an empty gas can in the back of my ICE car for piece of mind though I have never had to use it. Would a supplemental battery module with, say, 10-15 miles of range make any sense? Kind of a quick charge battery booster that you could pull out of the trunk (or frunk) when you've somehow managed to pull a Broder* and run out of juice.

    I'm guessing even a 15-mile booster would be pretty large (Maybe 5 kWH, assuming some transfer loss).

    Thoughts?

    -Chris

    *Bonehead from the New York Times
     
  2. EdA

    EdA Model S P-2540

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    It is called having a 120V extension cord and your charger cable in your car.
    I dread the road trip I take when I leave my charging cable behind plugged into my garage.
    I know its gonna happen.

    An empty gas tank costs less than a "full" battery - which by the way won't have any active temperature conditioning.
    There is a reserve in the battery (I've never tapped it) below 0 so I'm lead to believe.

    AAA in the state of Washington has some trucks with chargers on them.
     
  3. FlasherZ

    FlasherZ Sig Model S + Sig Model X + Model 3 Resv

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    Definitely do-able. It also depends on the timeframe in which you'd expect it to be charged. To dump 5 kWh into the Model S battery pack in 15 minutes at 350V, it would take 57 amps, which would take a cable roughly the size of an HPWC cable. It would take 420 cells for 5 kWh which would be sizable but not impossible - milk-crate sized, I'd imagine. Biggest issue is safety and cost - that's a lot of power to be dumped into the car, and you'd likely need some intelligent electronics, almost turning it into a portable DC charger to be fed via the charge port, supercharger-like.

    Note, all just a bunch of cheap speculation. :)
     
  4. AmpedRealtor

    AmpedRealtor Active Member

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    The trunk footwell would be a great place to store a backup generator or spare battery.
     
  5. MrBoylan

    MrBoylan Member

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    Yeah, but you'd need a really really long cable if it happens on a remote road like the northern part of the Taconic Parkway in NY or the two-lane highways in the Adirondacks where we drive in the Summer.

    Worst case - AAA flatbed I guess, which is no different than what would happen if I ran out of gas. I know there should be a super charger in Albany before I take delivery on my model X, so it shouldn't be an issue. But Just curious as to whether it's anything that's been considered. I guess that is the purpose of the reserve battery built into the main Tesla battery module.

    -CB

    - - - Updated - - -

    Oh, no you didn't! :) If I wanted a Volt I would buy a Volt!
     
  6. MrBoylan

    MrBoylan Member

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    #7 MrBoylan, Sep 13, 2013
    Last edited: Sep 13, 2013
    All good points. Thanks for the replies.

    -CB
     
  7. ChadS

    ChadS Petroleum is for sissies

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    I agree with the need for an extra reserve of energy in case you use more than expected; I think it's just cheaper and easier to leave that reserve in the battery rather than add some other system to put more in to the battery. I always plan my trips with a buffer, so if conditions are bad and I use extra energy - I can still make it to the next charge point, I just arrive with less charge than expected (and so it will take longer to charge up to where I need for the next leg).
     
  8. Zapped

    Zapped Model S - PURE EV

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    #9 Zapped, Dec 15, 2013
    Last edited: Dec 15, 2013
    Non EV'ers ask me all time, "what do you do if the battery runs out" and then in some cases immediately suggest I pull a generator; LOL.

    I mostly I tell them about the AAA truck mentioned early. Here's the link AAA-first-fast-charging-roadside-assistance-truck-seattle Does anyone know the kW output ?

    Another option would be to call your favorite contractor and have them bring out a trailer mounted diesel generator used in the construction industry. (Already available, multipurpose and easy to deploy)

    Could easily put out 240V and 30 Amps

    Screen Shot 2013-12-15 at 9.16.37 AM.png
     
  9. PokerBroker

    PokerBroker Member

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    I usually just say the same thing that happens when they run out of gas :). They usually respond that it never happens, to which I say "exactly!"
     
  10. iridium

    iridium Member

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    Slightly different than you are suggestion, but a while back there were rumors of a "drop tank" that you could put in the front to increase your range. People were suggesting a aluminum air battery I believe. I would love this, but it doesn't seem to be happening.

    For the emergency case, a while back I played with the idea of building an emergency power system using batteries and an inverter. I had no actual need for this, but have several large marine batteries sitting around so I couldn't resist the exercise. Basically it is doable, but even with a frunk full of marine batteries you're only going to get a few extra miles. :)

    FWIW, filling the frunk with marine batteries and driving around definitely impacts handling. :)
     
  11. Spurkey

    Spurkey P04251

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    I've tried using one of those power inverters just to see if it'd work:

    Inverters | Canadian Tire

    My cousin has a 2000W one which is more than enough to handle the 120V draw from the charge cable. The charger didn't seem to like it, it blinked red when we hooked it up, I suspect it's because these inverters put out a modified sine wave as opposed to a 'smooth' one. Figured I'd mention it in case someone else was about to try it. :)
     
  12. VolkerP

    VolkerP EU Model S P-37

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  13. Crispix

    Crispix Member

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    This is what I tell people who ask: "If a phone is plugged into the car it will automatically serve as a backup battery! A fully charged iPhone will power the car for about three miles."
     
  14. FlasherZ

    FlasherZ Sig Model S + Sig Model X + Model 3 Resv

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    The Tesla has a couple of requirements that may not have been satisfied. The Tesla expects a ground-neutral bonding somewhere in the infrastructure, because it measures the voltage relative to ground and wants to ensure it remains stable. In your case, ground for the 120V outlet may have been tied to the 12V ground of the vehicle, while the 120VAC output of the inverter was floating in respect to that ground.
     
  15. Cottonwood

    Cottonwood Roadster#433, Model S#S37

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  16. hughconn

    hughconn Member

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    I wish I had found this thread before I started building my attempt at this. I get enough juice from my inverter to power the mobile charger (flashing green) but the car reads 199/120 volts 12 amps and does not charge. If the issue is the ground, is it correctable from a battery-powered inverter?

    Is it possible to find an inverter that produces Tesla-friendly juice?
     

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