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Can't decide HPWC or NEMA 1450 - Advice?

Discussion in 'Model 3: Battery & Charging' started by ColoradoDave, Jul 28, 2018.

  1. timk225

    timk225 Active Member

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    #21 timk225, Jul 29, 2018
    Last edited: Jul 29, 2018
    If you're only driving 60 miles a day, or even 100 miles a day, the correct answer is that you don't need either a 14-50 or an HPWC. You need a 6-20. Get a double pole 20 amp breaker, a 6-20 receptacle and cover plate, a $35 6-20 adapter for your charging cable, and a roll of standard 12/2 Romex. 2 hot legs and a ground is how it's wired.

    You'll get 15 mph of charging without the expense of large heavy wires or the difficulty of pulling the larger, stiffer cable through the house. How long is the cable run from your breaker box to the outlet?

    I've only used my 14-50 once in the last month since I hooked up my 6-20. Getting down on the floor to plug in my 15 foot long Camco 14-50 extension cord in the oven outlet in the kitchen was too much hassle.
     
    • Informative x 1
  2. SSedan

    SSedan Active Member

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    There is some standard overhead to run the charger and computer on the Model S/X this is quoted as 400watts, this standard overhead means low charge rates are slightly less efficient than higher rates so long as you don't get into cooling.
    The sweet spot for the S and X is usually stated as 24amp of 240.
    I used a 30amp dryer outlet for a year, in winter it made for slow battery warming, slight range loss in morning warmup and the one time I needed to charge when a vacation was interrupted by a call from Mom saying they were putting Dad in an ambulance and I dashed home to drop off the wife and kids and do some vacation gear that 10minute stop was not enough at 17mph but at the 50+mph of the HPWC would have been or I could have stayed for an extra 5 instead I had to divert to a supercharger for a few minutes, cost me probably 20minutes total. Dad was in good hands, wasn't life threatening but that is what prompted me to finally put in higher amperage charging.

    Day to day in fair weather I could easily get my on 15amp 120volt, come winter the car needs to see more than the 24amps of 240 I gave it last winter, and then the unforseen emergency trip, that is when the HPWC purchase will be appreciated. I will set the daily amperage lower but for now am using it at max just to check everything stays tight and doesn't overheat. In a week I will double check all my work and connections and know it is ready for fast charging when I needed it.

    Also consider if "time of use" is a factor it is another good case for fast charging.
     
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  3. eprosenx

    eprosenx Active Member

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    I agree with everything you said, but one small point of order: You can install a NEMA 14-50 on a 40 amp branch circuit which is only rated for 32 amps continuous. While I typically would not do this, it is from my understanding code compliant and legal. This would allow you to use 8 AWG NM wire (romex). So that is probably about the cheapest way to install a circuit that will allow full speed charging on a UMC Gen 2.

    But yes, if you do the more typical install of a NEMA 14-50 using 6 AWG NM wire (romex) then on a UMC Gen 2 you will get 32 amps of charging, but if you used that same wire on a Wall Connector you can get 40 amps of charging. If you use THHN 6 AWG wire in conduit instead of NM wire then you can do a 60a circuit with the Wall Connector and max out your Model 3 Long Range charging ability (and as pointed out, you get to ditch the neutral conductor when using the Wall Connector which saves on cost).

    Oh, and 8 AWG in conduit will allow you to use a 50a circuit (so 40a charge rate) as long as the breaker and device on the other end (Wall Connector or receptacle) are rated for 75c terminals (most are).

    I love my wall connector!
     
    • Like x 1
  4. SSedan

    SSedan Active Member

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    Wire cost isn't that great though. 3 gauge copper thhn is all of $1.02 a foot.i figure ballpark $160 for wire and conduit for a 50ft. run.
    A spool of 8 gauge NM 3 conductor is $88 6gauge $95,
     

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