TMC is an independent, primarily volunteer organization that relies on ad revenue to cover its operating costs. Please consider whitelisting TMC on your ad blocker or making a Paypal contribution here:

Charging Card

Discussion in 'Model S: Battery & Charging' started by jellybeans, Jul 31, 2016.

  1. jellybeans

    jellybeans Member

    May 9, 2016
    Hey All,

    Thought I would share a charging card I made. It gives a good approximate on charging time. I have two J1772 chargers at my apartment complex and a ton of 110Vs in the garage. Given the battery state of charge remaining, I can use this card to decide where to charge.


    • Actual % (% of 75kWh)
    • Software Limited % (% of 70kWh)
    • Battery Level (State of charge of battery)
    • 110V (Time to charge to software limited 90 %)
    • DRT J1772 (Time to charge to software limited 90 %)
    • 14-50 (Time to charge to software limited 90 %)
    • Supercharger (Time to charge to software limited 90 %)
      • For the Supercharger data, I used the nice Google Sheet here.
    I've included the Excel spreadsheet if anybody wants to mess with it and configure it for their own purposes. You don't need to be an Excel wizard, but you should be comfortable with dimensional analysis (carrying your units).
    • Configurable to different charge sources. Different sources have different output power.
    • Configurable to account for vampire drain. I have energy saver mode off, connected always on, and front and rear Blackvue always on.
    • Configurable actual and software-limited battery size.
    • Configurable rated mileage efficiency. I have 70, which gets less rated miles per kWh than the 70D for example.
    Setting up:
    • Enter your correct battery size and software limited size.
      • If not limited, enter same number in both fields.
    • Enter your rated miles / kWh based on battery decay.
      • If you don't know it, just divide your 90% Rated Mileage by 90% of software limited size (or actual)
      • For example, my 90% on a 70kWh is 211mi as shown by the car. 90% of 70kWh is 63kWh.
      • So I'll enter "=211/63" in this field to get 3.349 mi / kWh.
    • Configure your vampire drain (if you don't know it).
      • Plug in your Tesla, set charge limit to 90 %.
      • Enter your power source voltage and max current.
      • Ensure the continuous current matches the readout on the Tesla.
      • Find the cell (under the appropriate power source) corresponding to your car's current state of charge.
      • Convert Tesla's time remaining to % of day.
        • Convert the time remaining on the Tesla app to minutes.
        • Divide this number by 1440. This is your % of day.
      • Do a goal seek, setting the cell you just found, to equal to your % of day, by changing the vampire drain cell.
    This is sort of a first prototype so I can print out my laminated charge card. I think it would be completely possible to make this into a full fledged API supported app than can re-calibrate automatically every time you charge.

    2016-07-31 12_53_47-20160731 Charge Table.xlsx - Excel.png

    Attached Files:

    • Like x 2
  2. Hugh Mannity

    Hugh Mannity Mediocre Member

    Jul 31, 2014
    Maple Ridge, BC, Milky Way

Share This Page