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Should I upgrade breakers/wiring for new 48 Amp Charger?

Discussion in 'Model S: Battery & Charging' started by ChrisJ, May 20, 2016.

  1. ChrisJ

    ChrisJ Member

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    I've yet to take delivery of my MS (due in the next two weeks) and I had scheduled the installation of a NEMA 14-50 for next week.

    Tesla is still recommending a NEMA 14-50 outlet but I'm concerned about running it off of a 50AMP breaker and #6 wires as recommended if I plan on running it at the full 48 Amps. I know I can limit the car to a lower rate but it would be nice if it could use the full range.

    Question is, should I bump the breaker to 60 Amp and use bigger wires (#4 instead of #6)?

    Originally my electrician was going to use NM-B 6/3 which is rated at 55 Amp, but there's also #6 65 Amp THHN (multiple single wires).

    There's a good chance I'll eventually replace the NEMA with a HPWC, so again it would be nice to run it at the highest capacity for the new 48 Amp onboard charger.

    Thoughts?
     
  2. Saghost

    Saghost Active Member

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    Well, if you're thinking you'll eventually want to run the highest capacity with an HPWC, maybe you should be thinking about wiring for 90 Amps - after all, Tesla is now saying the 48A chargers are all post delivery upgradeable to 72A...

    Aside from the HPWC future, I don't think it matters - AFAIK the UMC is limited to 40A even if the car can take more and the outlet has more capacity.
     
  3. ChrisJ

    ChrisJ Member

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    Thanks for the response.

    Yep, 72A upgradeable charger confirmed in the refreshed models, but I should have added that I'm pretty sure I'll not upgrade.

    I missed the UMC is limited to 40A, so it sounds like I have my answer - unless I decide to add a HPWC later. Can it set to somewhere between 40-48A?
     
  4. Amoroso6

    Amoroso6 Member

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    If you are already using #6 wire then go with the 60 amp breaker which will allow you to charge a the Max 48 amps the standard charger will take.
     
  5. David99

    David99 Active Member

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    I'm always for planning higher than needed, just in case. And it sounds like you are actually going to want a HPWC. The cost difference for a 65 Amp breaker and the bigger wires is probably small so I would go ahead and do that.

    Having said that, I drive a lot (30k-40k miles a year) and I'm totally fine with the 40 Amp UMC. I never wasn't able to charge as much as I wanted. There were a few situations where I would have a very quick charge, but even a 80 Amp dual charger would not have cut it. I have a CHADeMO at a mall near by. If I really need, that's still much faster even counting in the time to drive there.
     
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  6. Saghost

    Saghost Active Member

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    I'm not sure I understand the question. The new HPWCs can set to 40, or to 48 (50A wire/breaker, 60A wire/breaker,) or to several levels above and below that. I don't believe there's a level between 40 and 48, however, if that was the question.
     
  7. davewill

    davewill Member

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    You can't use a 14-50 of you go over 50a on the breaker. You could oversize just the wire and change the breaker if and when you install your HPWC.
     
  8. ChrisJ

    ChrisJ Member

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    Sorry, I should have read the manual, I knew you could set various levels but wasn't sure if there was any steps between 40 and 48. Thanks for clear it up.

    Thanks. That makes sense. I may add a sub-panel to allow me to add the HPWC later and go with the NEMA for now.
     
  9. Edmond

    Edmond Permanon

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    Don't use a UMC at 40 amps, or you'll be sorry.
     
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  10. swegman

    swegman Member

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    Why? I charge at 40A since getting the car over 3 years ago on the UMC. No problem with the it.
     
  11. jerry33

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

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    I suspect this will change after you take a couple of road trips.
     
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  12. kort677

    kort677 Active Member

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    the difference in speed of charging is what you should be concerned about.
    how fast the car charges from 0 miles to full is not a huge concern for me and many others, a few hours at most is the difference between the faster and slower charge rates.
    if you don't care about the costs and you think you need a faster turn around then do it.
     
  13. kort677

    kort677 Active Member

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    please elaborate.
    like another contributor I have charged my cars at 40 amps for a few years, what damages am I open to?
     
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  14. HankLloydRight

    HankLloydRight Fluxing

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    Same here, never had a problem with my original UMC at 40amps over 2+ years.
     
  15. ChrisJ

    ChrisJ Member

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    There's a new super charger going in 3 miles from my home, so any quick charges for long road trips would start there.
     
  16. Edmond

    Edmond Permanon

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    #16 Edmond, May 21, 2016
    Last edited: May 21, 2016
    Many people over the years report here that they've had one UMC after another fail. (One had his replaced 5 times) It was only when they dropped to 30A charge the UMCs began to last. Ya, I don't like it either.

    I realize your experience is different so far, but that doesn't matter when you have to buy a new UMC. Is your UMC warm or cool when charging at 40?
     
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  17. HankLloydRight

    HankLloydRight Fluxing

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    I live 3 miles from one supercharger, and 8 miles from another in the opposite direction. If you have a 40am UMC in your garage, I can assure you, you'll *never* use the local supercharger, even for long road trips.

    You simply charge your battery to 90%, 95% or 100% (depending on other factors) during the night before you leave and when you're ready to go, just go. And say your battery is already at 90% and you want to Supercharge to 100% before a "long trip", that's not a "quick charge", that's at least 30 minutes if not longer.

    Even at a lowly 40amps, you can fully charge a MS battery overnight.
     
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  18. Only Trons

    Only Trons Member

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    I am on my fourth UMC. I always charge at 40 amps. Most of the time I only need 1 - 1.5 hours to recharge back to 90%. A few times I've rolled back into my garage with around 30 miles remaining, so the car charged at 40 amps for somewhere between 6 and 7 hours. I don't believe (but can't prove/disprove) that problems with my previous UMCs were as a result of charging at 40 amps. No external damage (melting, disfiguration, etc) were seen on the 3 failed units. For each of the failed units, the service center told me that the contactors within the plug head were "bad". I've had my fourth UMC for about a year now with no problems.

    And in response to the question noted by @Edmond: my UMC is warm when charging for several hours -- but just warm....never hot.
     
  19. David99

    David99 Active Member

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    Early UMCs had some issues but Tesla swapped them out. I never had trouble, but they gave me a newer one anyways. I always charged at 40 Amp and it gets really hot here in the summer. Never had issues with the UMC.
     
  20. kort677

    kort677 Active Member

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    quite frankly I've never fondled it. this is my second model s and my second unit, both units have been problem free.
     

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