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How to determine the cost charging Model S?

Discussion in 'Model S: Battery & Charging' started by FrankOT564, Dec 10, 2015.

  1. FrankOT564

    FrankOT564 Member

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    I don't have the car but let's say if I get one... what will be by electric bill be like?

    I looked at my current bill it is about .0922 per killowatt.

    Can someone tell me how much it would be to charge lets say Model S from almost 0 to 90%?

    Thanks!
     
  2. Max*

    Max* Autopilot != Autonomous

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    0%-90% would cost different for a 60kWh, 70kWh, 85kWh and 90kWh model.

    There's a calculator on tesla's website, it should take into account charging losses from 120V vs. 240V and the buffer the car has.

    Tesla Charging | Tesla Motors Scroll to the bottom
     
  3. mikeash

    mikeash Active Member

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    That's 9.22 cents per kilowatt-hour. A kilowatt is a measure of power, a kilowatt-hour is a measure of energy. The latter is what you pay for.

    Typical Model S driving will use 300-350Wh (watt-hours) per mile. There's a bit of inefficiency in charging as well, so it's probably more like 330-385Wh/mile from the wall.

    If we assume the high end of that, then you're looking at .385kWh/mile * 9.22 cents/kWh = 3.5 cents per mile. If you drive a thousand miles a month, you can expect your bill to go up by about $35 if all of your charging is at home.

    For comparison, this is about what you'd pay to drive a gas car at $2/gallon if the car got 55-60MPG.
     
  4. FrankOT564

    FrankOT564 Member

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  5. HankLloydRight

    HankLloydRight Fluxing

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    When I got my Model S, gas was a little bit more expensive, but I calculated out that compared to my ICE vehicle (BMW M5), the Model S energy was costing me the equivalent of 37cents/gallon.
     
  6. FrankOT564

    FrankOT564 Member

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    My current 5 series BMW does 18MPG on average.
     
  7. BertL

    BertL Active Member

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    #7 BertL, Dec 10, 2015
    Last edited: Dec 10, 2015
    The answer is "maybe". It truly depends on the amount of energy you use in total, as well as what times of day you use it. If you're like some of us, there is also seasonal variation as to how much electricity you use, e.g when air conditioning is on in the summer the amount you use and when you use it may change dramatically like it does for me here in SoCal. In my case, SDG&E only allows its customers to change the rate plan once a year, so you really need to consider seasonal variation before making a change. Net is, you will have to go through your own calculations, as no one here can give you a solid answer.

    I went through this planning myself before ordering my MS in early September. I'd suggest you:

    • Get a handle on your own electrical usage by time-of-day, and understand seasonal variation
    • Establish what you think is an average and max charge (kWh) you will need to do each day with your MS based on the miles you expect to drive. Use the tools others have suggested above to get a handle on that.
    • Think through and decide on what type of electrical service (240V? What Amperage?) you are going to use to charge your EV... There are many trade offs between what your physical home situation may allow, cost, as well as how long it will then take you to charge your vehicle based on that service you have put in place -- e.g. If you only have 110V, it could take days to recharge an "empty" S90, or only a few hours on 240V depending on amperage. Read the charging section on the Tesla site and search for other threads on the subject as well -- lots of resources to gain a comfort level with your options.
    Note: A Tesla allows you to set the TOD when charging begins each day, but not a "stop time". Assuming your power isn't interrupted, it will stop when it reaches the % charge you've set (probably 90% or less most days, but that's a whole other discussion you'll find in other threads). E.g. My MS checks every day at midnight when my rates are lowest and begins charging itself if needed. I have a 240V 100-amp circuit along with an optional dual charger for my S90D, and in theory could almost charge it completely within the 5-hour window I have each day when my rates are lowest (at about 25% of the utility rate I pay mid-afternoon at peak rate every day)... I don't drive that much that it's that important, but I went through the thought process just-in-case as I'd suggest you do as well.​

    • Then, when you have those data points together, you can build yourself a little spreadsheet to see if converting to another plan with your utility makes sense or not, and/or perhaps you'd be better off to have a higher amp circuit to cut down on charge time so you can "refuel" more during the window when it costs the least...

    If you call your utility, they may also be able to offer some additional planning tools or guidance, once you have a handle on anticipated additional kWh you expect you will need with your new car each day. SDG&E here has a set of webpages to walk its customers through some of the basics interpreting your bill, etc., but I had to then apply all the Tesla-specific stuff to it. Good luck.
     
  8. jcaspar

    jcaspar Member

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    For a full charge, I use a simple formula for my P85. Cost for full charge=(85kW x kW cost in cents)/.85 or cost of a kW in cents is the same as a full charge in dollars. So 9.22 cents per kW is 9.22$ for a full charge with an 85.
     
  9. jamieb

    jamieb Member

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    I have a Time of Use rate ($0.06/kW) with my utility. The first year I had my car I put 12k miles on it, I used SuperChargers and free 'opportunity' charging elsewhere maybe once or twice a month when taking a road trip elsewhere in Northern California, but overall that first year, easily 90% of my charging was at home at night.

    Because the car charging is called out on my utility bill, I was able to calculate my out-of-pocket cost/mile - it was $0.02/mile :smile:

    When I had the electrician put in the 240V circuit, meter and sub-panel to qualify for the TOU rate, I had him run conduit to the other side of the garage with a NEMA 14-50 plug where my wife parks to 'future proof' the garage for an EV. Think about doing that if you're going to have your garage wired for an EV. For me it added <$100 to the cost of the install. We're waiting on her 2016 Volt to arrive and I already have an EVSE set up for her new car.
     
  10. Config

    Config Member

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    I wish I figured in having an EV before I had our solar array system installed.
     
  11. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    Charging isn't 100% efficient, so at 9 cents per kWh, and some Supercharging on trips, I figure using the kWh on the car is about as close as I can come without metering at the wall. Basically that works out to four miles for a dime. (1000 Wh / 250 Wh/mi = 4 miles). Last month my total electric bill (all grid) was $107 charging a Tesla and a Leaf plus household use. Without trips the Tesla travels 50-60 miles per day, and the Leaf travels about 30 miles per day.
     
  12. DaveWaterloo

    DaveWaterloo Member

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    Buy an Eyedro from amazon and put it on your charger circuit. I get a report every week on how much it costs to charge or I can look on cloud dashboard anytime I'd like. It is smart enough to always take TOU billing into account.
     

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