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Help with HPWC install

Discussion in 'Supercharging & Charging Infrastructure' started by Club206, Sep 9, 2019.

  1. Club206

    Club206 Member

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    Paramus NJ
    So I have the high power wall charger that i am setting up in my garage. Breaker box is 200a and I have no room on my box but electrician said we can do a tandem breakers to create space so not a problem.

    Electrician said we could do a 240 volt 60 amp direct line. Does that make sense and will that max my power to the HPWC. Rather ask here then ask the electrician for the moment. How many miles can I expect?

    Thanks everyone!
     
  2. Ostrichsak

    Ostrichsak Member

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    I assume the electrician means to put your HPWC on a separate circuit attached to a 60A breaker? Assuming this is the case, the maximum you can pull is 48A given the 80% safety margin.

    That being said, this isn't the only limiting factor that determines your max charge rate. The car itself needs to be capable of higher charge rated.

    Do you have dual chargers in your car? Often times cars come with only a single 40A charger in which case anything above a 50A install is a waste unless you want to give yourself more flexibility for future upgrade.

    This is also why most people choose to install a simple NEMA 14-50 outlet (240v 50A) & use their UMC.
     
  3. Club206

    Club206 Member

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    I have a Model 3 so not sure about dual chargers.
     
  4. Ostrichsak

    Ostrichsak Member

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    Dual chargers is (was?) an option in Model S cars that allows them to charge @ ~60mph on a HPWC wired to a 100A circuit. Model 3's are different & I'm no Model 3 expert.

    If it's a long range I believe they have a 48A onboard charger which would be a perfect match for the 60A solution your electrician has quoted since 80% of 60A is 48A.

    If it's a standard or mid range Model 3 they have a 32A charger so it wouldn't charge any faster than a 40A outlet as the car's charger would be the limiting factor. Then it comes down to if you want to allow for future increase in charge rate for another car since the wiring is expensive so you don't want to waste money on something you'll never need.

    If there's a chance you'll ever own something that has a higher charge rate go ahead & wire it to 100A to allow for the maximum charge rate possible by the HPWC.

    Be warned, depending on the distance from the circuit breaker to the HPWC the price difference between 60A & 100A wiring is substantial. This why it's important to know if you'll ever utilize that additional capacity. The only thing more expensive would be installing 60A & then later wanting to rip it all out to go to 100A.
     
  5. dk10438

    dk10438 Member

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    Should be fine. I believe the M3s can only accept 40 or 48A anyway. You want the current to be 80% of the capacity of the circuit so 0.8x60A=48A
     
  6. srs5694

    srs5694 Member

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    This is exactly correctly -- the Model 3 LR can charge at 48A, vs. 32A for the SR/SR+ (and now-discontinued MR). A 32A charge rate delivers about 30 miles of range per hour, vs. 45 miles at 48A. (These figures assume a full 240v. It can fluctuate a bit from one house to another, and over time; and business installations sometimes provide 208v rather than 240v.)

    Note that even if you ever get a car that can take more than 48A, that car will almost certainly be able to drop down to 48A, so you'll still be able to use an HPWC that's set up with 48A as its limit. Cars that can take more than 48A would normally have bigger batteries, and perhaps be less energy-efficient, than a Model 3 LR. The main times you'd have a real need for over-48A charging would be if you were driving such a car and got back from a road trip with a nearly-depleted battery and wanted to fully charge it overnight; or if you have multiple EVs and want to charge both of them reasonably quickly (say, to finish charging one before going to bed and then to swap to charge the other one overnight). These scenarios might or might not be important to you.
     
  7. Rocky_H

    Rocky_H Active Member

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    I know the discussion below may have sounded a little overwhelming about the amp limits in the different car models, but I did want to make it clear that it is always OK to have a higher circuit to your wall connector. It can make a larger amount available, but lower power cars will only take what they need from it.

    I use the analogy sometimes like a very large buffet, but people with different sized plates can still go there to take how much they want.
     
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