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Manually Adjusting Amp for Non Tesla Plugs

Discussion in 'Model S: Battery & Charging' started by hashraf, Dec 16, 2015.

  1. hashraf

    hashraf Member

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    I am planning on using the Nema 10-30 dryer outlet which is ~25ft from the charge port. Hence I need an extension cord (50AMP from Camco) that connects to Tesla's Nema 14-50 on one end and then a converter that converts 14-50 to 10-30 on the other end and then that 10-30 connects to the outlet.

    Since there is no tesla 14-50 to 10-30 adapter, I need to buy the following: NEMA 14-50R to 10-30P Adapter

    From what I understand, the car will try to charge at 40Amps even though it shouldn't be charging at more than 24Amps as the extension cord is connected via Tesla's 14-50. What is the sequence of events for manually dialing down the AMPs for charging i.e.

    Plug the cable to outlet, then put the cable in charge port and then quickly jump inside the car to manually adjust the Amps to 24 before the car tries to reach 40Amps? What If i cant get to the car quickly and adjust the amps. Would the outlet, wiring get damaged as the car will try to immediately pull more Amps then it should? Is there a way to bring the Amps down even before the cable is connected to charge port?

    Also from what i understand, the car remembers manually adjusted Amps for the location. What if next day I just use the regular 110V outlet without extension, etc. Would the Tesla Adapter automatically adjust to 12V? And what if I then once again go back to my extension/adapter combo and connect to 10-30. Would it remember the 24A or it will once again try to get 40A?
     
  2. AWDtsla

    AWDtsla Active Member

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    You can change it before you plug in.
     
  3. blanche

    blanche Member

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    Once you plug the EVSE into the car, you get the option to dial down the amps. It takes quite some time for the amps drawn to increase so you have plenty of time to jump in the car and dial it down appropriately. You cannot do this beforehand.

    Also, if you change source (110v instead of a 220v 10-30) then you have to remember to manually adjust the amps drawn in the car. Remember, with these "dumb" cables, the car can't tell whats the source. There is no communication protocol between the car and a "dumb" wall socket.

    The worse that will happen (I hope) is that you will overdraw the circuit and trip a circuit breaker. I've done this plenty of times (by accident) without burning the house down. The only problem is you can't tell you've done this unless you check the phone app to see if the car is still getting power. I think you're overanalyzing this. You'll make a few rookie mistakes -- we've all done it -- and then you'll figure out a method that works for you.
     
  4. Max*

    Max* Autopilot != Autonomous

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    I was going to do the same thing you want to do OP, use a 50' NEMA 14-50 extension cord with a NEMA 14-50 to 10-30 adapter and my NEMA 14-50 plug.

    But after reading a lot of Flasherz posts (and other people), they brought up a very good point. If Tesla resets itself and resets the amps to 40a from 24a that the dryer plug can supply, if the breaker/wire/etc. aren't correct/perfect you may start a fire.

    Sure, it's a lot of "if this then that" that are unlikely, but it's still a possibility.


    For a few bucks more (maybe not even?) I bought a 50' NEMA 10-30 extension cable and a NEMA 10-30 plug from Tesla that I plan on using at my inlaws over xmas.

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    Except if you change your NEMA 14-50 adapter (240V 50A) to the NEMA 5-15 adapter (120V 15A), the car will know and will automatically limit charging to 12A.
     
  5. AWDtsla

    AWDtsla Active Member

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    Not worth the weight and expense. You might only get fire if breaker is defective. Treat it just as you would an open flame anywhere else and it will be fine.


    edit - and think of the case where electricians tend to put 15A sockets on 20A circuits. I have an adapter specifically for this, which requires you to exceed the plug rating.
     
  6. Max*

    Max* Autopilot != Autonomous

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    For me it was less weight and less cost (14-50 50' extension + 14-50 to 10-30 adapter vs. 10-30 50' extension and 10-30 tesla adapter)

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    Odd... just noticed it's no longer in the Tesla store, I picked up a Tesla 10-30 last week. This used to be the link: http://shop.teslamotors.com/collections/model-s-charging-adapters/products/nema-10-30

    Email your local SvC and see if they have any in stock, you may get lucky.
     
  7. hashraf

    hashraf Member

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    Yes, i noticed it too this morning. My SC had it last week so they may still have it. I'll call them.

    Max, did you get this extension cord? Amazon.com: Camco 55197 30 AMP 50 PowerGrip Extension Cord: Automotive

    Is this the right one?
     
  8. Max*

    Max* Autopilot != Autonomous

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    No, that would be a great price though. It looks to be the correct gauge, but that's for 120V applications, not 240V (pins are wrong TT-30, not 10-30).

    If you want to stick to Amazon, this would be the correct one: Amazon.com : Conntek Rubber SJOOW 10/3 NEMA 10-30P 3 Prong Dryer Rubber Extension Cord, 25-Feet : Patio, Lawn Garden

    I got this one: NEMA 10-30 Dryer Extension Cords, 30A (125/250) Corddepot

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    If you're handy you can make your own, home depot sells 10-3 cable, you can get a dryer receptacle and either a dryer plug or you can order nicer dryer plug online. It'll cost you less than anything pre-assembed, and is a pretty straight forward project.

    Actually, if you're building it yourself, you can do a 14-50 to 10-30 cable, so you can skip the adapter all-together (I contemplated doing this)
     
  9. Cyclone

    Cyclone Active Member

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    Not to mention the 10-30 extension is much lighter. For me, when I thought about it, I figured that anytime I would want/need an extension, I would most likely be charging off a dryer outlet. As such, a 50 amp cable was overkill and a 30 amp cable was sufficient. 50 amp plugs would be ovens (if properly circuited), other EV plugs, or RV parks were I could park the car close to the plug. As such, no sense in keeping the heavy cord when I would be using 30 amps most of the time.

    Sadly, I couldn't find a worthwhile 30 amp extension cord, so hopefully Max shares a link for his. I ended up finding a Tesla NEMA 14-30 adapter at a Service Center and use that + a 14-50P/14-30R adapter with the Camco 50 amp cord since that was cheaper than building my own 30 amp 3-wire cord.
     
  10. Max*

    Max* Autopilot != Autonomous

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    Link above, it's expensive though. $150 and they had a 10% coupon, so $135 shipped.

    I was going to go the DIY approach, but for whatever reason just bought the pre-assembled cable.

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    OO, I remember why I bought the cord depot one instead of DIY. The in-store DIY cables were mostly NM-B and not shielded in the nice flexible rubber jacket, and I needed something that's going to bend many times, and I guess I was too lazy to continue looking for the correct type of cable.
     
  11. Cyclone

    Cyclone Active Member

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    I see you posted it while I was authoring my post. Yeah, I came to the same conclusion with my 50 amp cord. 14-30 was $45 just like the 10-30, so the adapter cost was the same either way. I picked up the Camco 50 amp 30 ft extension for $90 and DIY (http://cosmacelf.net/Home%20Made%20Adapters.pdf) a 14-50R/14-30P and 10-30P adapters for another $20.


    I wanted to order this one, but the seller wouldn't respond to my requests if they could build one longer than 20 ft. This is a 3-wire 14-50 extension cord, so it's much lighter than the Camco one.
    Heavy-duty NEMA 14-50 extension cord for Tesla, 20 ft.
     
  12. Max*

    Max* Autopilot != Autonomous

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    That cosmacelf link is awesome, I studied it extensively when I was planning the DIY route.

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    I emailed these guys a few months ago asking if they can make a 50' 10-30P to 14-50R cable, no response either...
     
  13. AWDtsla

    AWDtsla Active Member

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    Turns out, you can run 40A continuous over the 10-30 extension anyway, as long as you keep the cable open to air. If I hadn't already built a 6 gauge cable I would have done this. A proper 50A extension is bigger and has less temperature rise than the UMC cable you're plugging into it.
     
  14. hashraf

    hashraf Member

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    Fortunately, I just need a 15ft cord, so that one at corddepot is much cheaper but shipping is crazy on orders under $100. My other alternative is to back my car into the garage each night but given the tight space (i have to fold mirrors and have about one inch extra space front and back) backing seems scary if I do it everyday. Once in a while its ok but everyday would be a pain. So I will just buy this corddepot 30amp 15 ft extension cord and get the 10-30 adapter from local SC. They do have it although online it has disappeared. This way i wont have to worry about making sure the car is using correct Amps.

    Hopefully the 30amp (or 24amp in reality) is much more efficient in terms of energy losses than the 110V charging I am using.
     
  15. Max*

    Max* Autopilot != Autonomous

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    On 110V/15A (12A) I got about 4mph.

    I haven't tested the 10-30 cable yet (I will in less than 2 weeks), but IIRC it's supposed to be around 16mph.
     
  16. green1

    green1 Active Member

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    To get back on topic, can someone confirm, you must set the current limit AFTER plugging in? not before? that seems like some incredibly horrible design work...
     
  17. hashraf

    hashraf Member

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    i mean't energy losses not speed of charge. From what I have heard, 50A chargers are about 80% efficient and 110V ones are probably 60-70%. Hopefully 30A is close to 50A in terms of loss of energy.
     
  18. Max*

    Max* Autopilot != Autonomous

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    Ah, gotchya.
     
  19. AWDtsla

    AWDtsla Active Member

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    See post #2.
     
  20. FlasherZ

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

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    Unless it happens in the wall, no "open flame anywhere else"... My home in California was about 20 minutes from burning to the ground when the breaker failed to trip due to a bad splice within the wall. There are reasons for the NEC.

    And the breaker doesn't even have to be bad. I've seen 30A receptacles melt when 30A continuous load was drawn from it for over an hour. That's why 24A is the limit for continuous loads.

    Tesla may (and has) reset the software charge limits after an upgrade, and as breakers don't trip at target_current + .001A, the potential consequences are significant. Bottom line recommendation from me is that you should trust "dialing down" only for an occasional need (like at a RV park with bad breakers), but for more permanent needs get it done correctly.

    This is legal, and in fact much of the testing is designed to ensure that 20A would not melt a 15A receptacle (dirty little secret is that most 15A receptacles are built on the same equipment with the same materials as 20A receptacles, they're just sold as 15A to limit people from plugging 20A devices into 15A wiring).

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    The car slowly ramps up to the target current, so you get some time to do it even after you plug in.
     

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