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HPWC on 100amp breaker. Any reason not to have it set to 80amps?

Discussion in 'Model S: Battery & Charging' started by JMG, Sep 18, 2015.

  1. JMG

    JMG Member

    Feb 26, 2015
    NE Texas
    I only have a single charger on my vehicle, but purchased the HPWC because I wanted to keep my UMC in the car at all times. When the electrician was hooking it up, I had him go ahead and install it on a 100amp breaker in case I ever wind up adding the 2nd onboard charger in the future.

    Since I can only charge at 40amps, I've left the dip switches on the HPWC at the 40amp limit. However, occasionally I'll have a PlugShare driver come by with dual chargers. Should I just leave the dip switches set to 80amps and just let the car handle the charging at 40amps so I don't have to take the cover off and switch the dip switches back and forth?

  2. bollar

    bollar Disgruntled Member

    May 1, 2013
    Southlake, TX
    There's no downside to setting the HPWC at 80 amps and it'll save you from potentially breaking the innards.
  3. wk057

    wk057 Senior Tinkerer

    Feb 23, 2014
    Hickory, NC, USA
    If it's on a 100A breaker with appropriate sized wire (should be!) then just set it to 80A. It won't make a difference to your car if you have a single charger, since it'll just suck up the 40A it can. It's just changing the signal the HPWC sends to the car to tell it the max available power, which should be 80A on a 100A breaker. Another owner with dual chargers, such as myself, who charged there would get the 80A they should get from the 100A circuit. Changing the dip switches won't affect how much power it uses or your car uses with a single charger.

    Or you might find yourself wanting dual chargers one day. I've found this to be one of the most valuable options I've gotten on the car.
  4. FlasherZ

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

    Jun 21, 2012
    I agree with the posts above, no reason not to just leave it set up at the 100A setting.

    Some people believe that charging at 80A all the time might impact your battery longevity, but it has not affected mine to this point. Even if that occurs, you can set the car to draw a lower amount and it will happily remember that choice.

    Likewise, 80A can generate a lot of heat in the charging cable as the sleeves wear; some people prefer to use 56A charging which will generate only half the heat. You can set that in the car while leaving the HPWC set to the 100A circuit size.
  5. William13

    William13 Member

    Mar 19, 2011
    South Bend
    The biggest downside is a warmer garage during the summer.
  6. GSP

    GSP Member

    Dec 28, 2007
    But not for the OP, since he will still be charging at 40 A with his single charger.

  7. AmpedRealtor

    AmpedRealtor Active Member

    Jun 30, 2013
    Buckeye, AZ
    Set the switches to the maximum level. You will charge at whatever rate you specify inside the vehicle, and anyone else can do the same. No sense in limiting the hardware.

    The reason for the dip switches is to address situations where you have installed the HPWC on anything less than a 100A circuit.

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