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HPWC: what level do you set it at.

Discussion in 'Model X' started by hill, May 16, 2018.

  1. hill

    hill Active Member

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    48? ..... 72? .... Lower? .... higher? During the day i find we typically have about 5kW's of Surplus that we would have feeding back onto the grid from our solar. Thus, since that works out to ~20amps of 240V - i set the X's max charge power level down to 20 amps - & w/in 3 to 4 hours, turning on season & drive patterns, that does the trick for our daily use & keeps the post-harged range no higher than an 80% charge. anybody else have any particular HPWC patterns? we got a $300 deal on the unit & I wired it in myself, so it could run @ 72amps in a pinch. The unit seems kind of overkill, but for those rare exceptions when we need much more charge, much quicker, I didn't want to pass it up, even though we always have enough range on hand to get to the closest supercharger, regardless whether we had north, south, or east.
    .
     
  2. McManX

    McManX Member

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    100 amp, always at max rate, charge to 90%
     
    • Like x 1
  3. ChuckG

    ChuckG Member

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    Charging at a lower rate is good for the battery. If it works for you keep it up.
     
    • Disagree x 5
  4. HugoBoss

    HugoBoss Member

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    Max power!!!!
     
  5. mal_tsla

    mal_tsla Member

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    With a temperature-managed battery, the less time spent charging, the better.

    Charge at fastest rate that makes sense for your situation
     
    • Like x 2
  6. aesculus

    aesculus Still Trying to Figure This All Out

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    On a 100 amp breaker and it's set to 72 amps always. I have only once had to charge quickly but when I did, it was nice to have it.

    I have come home very late at less than 10% and needed to go out the next day. While I am sure a lower charger and setting might have made it OK, it was nice to know that somewhere around 4AM I would be good to go again.
     
  7. NickFie

    NickFie Member

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    HPWC has 100 Amp, 2-gauge copper circuit. Two scenarios, two power levels.

    A. Daily use. 20 - 40 Amps. During the winter, I try to juggle start time and current so charge is nearly complete - 60% - 70% - by the time my wife will use the car. That provides a warmer battery. No problem falling short, it takes several days of local driving before the battery is as low as 25%.

    B. Prepare for a trip. Charge to 90% at same, relatively low current the night before. An hour or so before departure reattach the charger. Dial up to the S100D's full 72 Amps, set the limit to 100%, pack the frunk & trunk...

    Last Sunday a friend with a dual-charger S85 visited. His car pulled the HPWC's full 80 Amps. I thanked him for verifying the electrician's work. He reported that was the fastest charge he'd had without a Supercharger. His car was back to 100% by the time he hit the road again after a short nap and dinner with our family.
     
  8. ewoodrick

    ewoodrick Member

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    This is really scary. Electrical circuits should be installed so they work "in a pinch" The device should be set at the design capacity of the circuit. (that's not just the self-instlled breaker current)
     
  9. tpham07

    tpham07 Active Member

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    48A. My car doesn't take any more so there's no point haha.
     
  10. brkaus

    brkaus Active Member

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    Installed my HPWC on a 50a breaker so I charge at 40a. Better electric rates. It would cost me $20 more per month to go higher.
     
  11. AEdennis

    AEdennis Active Member

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    56 Amps on our HPWC since it was insanely expensive to install 100Amps to charge the dual chargers at 80A...

    However, we usually charge at 30A and 40A on J1772 CT-500 and NEMA 14-50 circuits...
     
  12. TexasTeslaRacing

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    All the way to 11
     
  13. aesculus

    aesculus Still Trying to Figure This All Out

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    Can you explain this? I guessed you are an Austin Energy customer and could find nothing on their website that stated they would/could adjust a price by delivery rate, just tiered usage (ie total consumption).
     
  14. Rockster

    Rockster Active Member

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    Our HPWCs share a 100 amp breaker. The S can charge up to 80 amps but we charge at 41 amps so as to share the burden equally between both onboard chargers (it's a dual charger S). The Model 3 charges at 32 amps. Even though it could charge higher amperage, we rarely need to.
     
  15. brkaus

    brkaus Active Member

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    Pilot program for off peak ev charging.

    https://austinenergy.com/ae/green-power/plug-in-austin/residential-time-of-use-rate

    *A flat rate of $30 per month applies for EV drivers requiring a demand of < 10kw. For a demand of greater than 10kw, the fee is $50 per month.
     
    • Informative x 1
  16. hill

    hill Active Member

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    #16 hill, May 17, 2018
    Last edited: May 17, 2018
    help me understand. So what's wrong w/ dialing down the car's max (amps) accepted delivery rate? And ... Why would the HPWC even have a 48amp setting, if as you say, it should be set at the capacity of the circuit?
    why.....
    - maybe direct me to a link i can read? seems the documentation on the car's "range" mode/setting says something about (for example) range mode warming the pack "up" if it's too cool (besides other range-extending functions) - because the warmer battery, compared to cool will be providing a more optimal range. So regardless if we set charging at 70 40 20 or 5 amps ... it'd make sense the thermal management would either cool or warm the pack accordingly - as needed. No?
    And thanks, everyone - for providing the rational for your choice of charge/current speeds.

    .
     
  17. aesculus

    aesculus Still Trying to Figure This All Out

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    Very interesting. I suspect we will see more of these types of programs emerge in the future. With a sub meter they can do all sorts of thing such as figuring out when best to charge your car to meet grid needs or to try to balance your demand in premise etc.

    And of course for those of us who have whole home energy systems built around a cheap EV charging rate, this type of solution will negate that.
     
  18. brkaus

    brkaus Active Member

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    Yes, I believe somewhere in the contract I agreed that they can control the power. Even replace, at their cost, my EVSE with one of their choosing.
     
  19. aesculus

    aesculus Still Trying to Figure This All Out

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    There may be some confusion here perhaps in all of the posts. I can see nothing wrong with dialing down the car to a lower rate so you don't exceed your solar output. In fact that is a great idea.

    And yes, in very cold situations (probably not going to happen in Lake Forest) if you go too low you will not get the added benefit of having the charging warm the battery, so the car would have to make up for this when you start your drive. But that use case is a bit complicated anyway as you have to time your charging to match your departure time etc.

    As long as you have your HPWC set to no more than 80% of your circuit capacity (breaker plus conductor), you should be fine.
     
    • Like x 1
  20. Freedom101

    Freedom101 Member

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    My X only takes 48amps. I had the electrician set the hpwc to the Mac setting (72 amp) when it was installed. Is this costing me more to charge than if it were set to 48? Forgive my ignorance on the subject
     

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