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Real "fuel" cost comparison ICE versus Model S

Discussion in 'Model S: Battery & Charging' started by AustinPowers, Feb 22, 2013.

  1. AustinPowers

    AustinPowers Total Smeghead

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    #1 AustinPowers, Feb 22, 2013
    Last edited: Feb 22, 2013
    Ok, I tried to find a thread about this, but other than some single posts hinting at the point I am looking for in various threads, I couldn't find anything about this.

    My question is, now that the Model S is around an quantity, how is it affecting the electricity bill of its owners.

    I know it is often stated how much money you can save when comparing the S to an ICE "fuel"-wise, but how is it in real life? I am asking this especially now that we know about things like the power drain in cold weather, which I am sure will factor in quite a bit into the equation.

    Also the often stated "advantage" of being able to plug in the S every night at one's own home to start each day with a full, say 200 to 250 mile, range will have an effect.

    Not having known a lot about EVs before I joined this forum, I quite naively assumed that an EV was somewhat like a mobile phone (or any other rechargable-battery-driven device). I.e. you charge the battery to full, then use the device until the battery is completely/almost completely empty, at which point you plug it in and recharge it to full and the circle of life begins anew.

    I therefor also assumed (when I did the simple math for my first cost comparison) that the Model S gets me 300 miles (ok now I know 265 miles under EPA conditions) per charge of 85 kWh. That way I also calculated without any losses, which of course I know now was completely unrealistic.
    But how does the S fare under realistic conditions? If I plug in the car each night, I never really know how much electricity it actually uses in total over a given period of time, or do I?

    Does anyone have an idea about what the real usage is, when plugging in the car (almost) every night? In other words, how much it "weighs" on your electricity bill - which can make quite a difference especially if that electricity is as expensive as it is over here in Germany.

    Thanks in advance for your input.
     
  2. Doug_G

    Doug_G Lead Moderator

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    In a typical month I have about $50 extra on my power bill, versus about $250 of gasoline previously.

    Road trips are particularly inexpensive - to date I've never had to pay for charging on the road. So I only have to pay to refill it at the end of the trip. I've done 900 km trips that cost under $10.
     
  3. GSP

    GSP Member

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    Several members have a TED measuring device or similar. Hopefully they will post their results here.

    EPA ratings measure the energy *input* to the car's on board charger. Their 38 kWh/100 mi rating should give you a very good idea what to expect, given your miles driven per month and your electric rate.

    In the US, electric rates can be hard to figure out with various fixed monthly fees and various surcharges on energy consumed. Often the base rate is different for the first several kWh/month, then a higher rate to another kWh threshold, above which the rate is even higher. On top of this I have three surcharges, and they are not published with the base rate info. I guess I should not complain, since it adds up to less than $0.05/kWh off-peak. :wink:

    I hope things are simpler in Germany!

    Here is a link to EPA's 85 kWh Model S rating at fueleconomy.gov:

    Compare Side-by-Side

    GSP

    The 3-phase charger for Europe may have a slightly different efficiency compared to the US single phase model. I doubt it will be noticeable in your electric bill however.
     
  4. allanb4me

    allanb4me Member

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    Ok.. cool.. and will goin for solar charging at home cut off that $50 also?
     
  5. mnx

    mnx 2013 P85

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    #5 mnx, Feb 22, 2013
    Last edited: Feb 22, 2013
    I've got 615.2km on the car and have pulled 199.9kWh from the wall yielding 324.9Wh/km (note the cars display says 246Wh/km).

    It's been pretty cold here the past week, vampire losses overnight have been greater than 1km/hour at times.... I've also been preheating the car before I take it out.

    Since this thread is about costs, I'll add mine in. (doh!)

    200kWh of electricity is ~$24

    To drive our minivan ~600km it would cost (12.4L/100km = 74.4L * 1.30$/L = 96$

    In my case driving the Tesla costs 1/4 as much...
     
  6. ModelS8794

    ModelS8794 Member

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    (199.9 - the energy currently in your battery) / miles driven

    would be the proper Wh/km calculation, right?
     
  7. mnx

    mnx 2013 P85

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    No, that would leave me as pulling far less energy from the wall than the car has consumed...
     
  8. ModelS8794

    ModelS8794 Member

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    Hm, I guess that would only work if you started from empty. If you are full now and received delivery with an equally full charge, then you could ignore your battery's "inventory". If start and end were different SOC you'd want to account for that in your calc.

    All IMO
     
  9. mnx

    mnx 2013 P85

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    Right. My battery was full on delivery ( I don't remember the exact number of ideal miles, I also had 36km on the odometer... However as I put more km on the car, the initial #'s will become less of a factor.)

     
  10. mknox

    mknox Well-Known Member

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    That would work out to 12 cents / kWh which is likely low. (I am a VP at an Ontario electric utility responsible for, among other things, Billing). By the time you Loss Adjust and add all Commodity, Regulatory and tax charges it'll be closer to 14 cents Off-Peak, 19 cents Mid-Peak and 21 cents On-Peak.
     
  11. kendallpb

    kendallpb Model S: P 8061

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    That's not a good way to handle a cell phone, either. Most these days, methinks (certainly mine, the iPhone) have batteries that are best kept topped off to maximize battery life--like the Model S! Plus, you know, you're unlikely to actually run out of juice on your phone and find it useless, if you keep it charged. ;-) I charge mine each night, no matter how much juice it has left; I charge a little more than that, since I'm at my computer at home a lot and frequently plug it in there to sync or just to keep it topped off. (shrug)

    So while phones and electric cars do compare, IMHO you and many mistreat their phones, so the analogy winds up causing problems. They both should be kept topped off.

    I don't see how recharging every several days or week, or every night, affects this. Either way, you're monitoring your electricity usage that closely or you're not, right? Heck, if you monitor it really closely--I do not--then, recharging each night, you're basically "filling up" based on your usage so it should be even easier to keep track of. Again, I don't monitor things like that (or at all). I'm making multiple changes over the next few months, so I'll probably never know the impact precisely. New Model S two weeks ago, adding solar panels in the next few months, and doing home energy efficiency improvements at the same time . . . at the end of all this, all I know is that I expect lower bills. I know, bad way to make changes, but it's all kinda related (well, all through Solar City) and we're into this stuff right now.

    Heck, I'm also thinking of switching electricity suppliers (though looking over the possibilities and trying to compare to my Pepco bill gives me a headache!). Another change to throw off any hopes of me knowing how much any of this helps my bottom line. ;-)

    (I never kept track of my gas spending closely, either, BTW; I'm guessing I'm not alone in this.)
     
  12. mnx

    mnx 2013 P85

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    #12 mnx, Feb 22, 2013
    Last edited: Feb 22, 2013
    I did the math using the rates on Horizon Utilities webpage. 10.6c/kWh or 11.98c/kWh after HST with off peak rates. There are fixed monthly charges of $15.84 but I won't include those because I have to pay for electricity regardless...
     
  13. Elshout

    Elshout Member

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    I lose about 10 miles (16 km) per day just sitting in my garage overnight. I drive about 21 miles (35 km) per day on average. So I really use about 31 miles or 51 km worth of electricity per day on average. As I live in the Peoples Republic of California with just about the highest electricity costs in the U.S., my average cost per kWh is about $0.20. My utility bill increased about ~$10.00 per week or ~$43.00 per month. My S550 Mercedes used close to $200 per month.
     
  14. Tesla 940

    Tesla 940 Member

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    #14 Tesla 940, Feb 22, 2013
    Last edited: Feb 22, 2013
    Recalculate ?

    Interesting Calculation. Unless you are actually comparing pre-MS bill to post-MS billings - I figure it differently as follows:

    31 miles x 325 wh/mile = 10.075 wh

    10.075 wh x 1.25 = 12,593 wh (25% engergy loss from meter to battery for AC to DC)

    12.6 Kwh x 5 days = 63 Kwh

    63 Kwh X $0.20 = $12.60/week.

    Also, using "average" cost is probably inappropriate since you are not using "average". You very may well be in a tiered rate structure therefore your additional useage for the MS is in the highest tier or two. Your real rate could easily be $0.25 or up to $0.36 per Kwh. At $0.36/Kwh your weekly cost is something like $22+. Still alot less than $200/mo but not nearly the $10/month you think it is costing.

    More questions - if you are losing 10 miles each night - what are you losing during the day while the car is likely just sitting in your workplace parking lot? If not included in your calculation - your true cost just went up some more. Also, what about your non-commute miles? Your monthly commute is ~ 440 miles yet your S550 gas bill was $200/month???. Assume $200 / $5 gas = 40 gallons x 15 mpg (my friends E63 gets better mpg) = 600 miles. If you compare Apples to Apples then your cost for 600 miles per month is more likely $50 - $85 per month.
     
  15. AustinPowers

    AustinPowers Total Smeghead

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    #15 AustinPowers, Feb 25, 2013
    Last edited: Feb 25, 2013
    Thanks for the input. I guess the 38 kWh per 100 miles might really be a good point for me to start.

    Things in Germany are not really simpler, just different ;-)

    For example many people have a small basic monthly fee (between 5 and 15 Euro) which you have to pay even if you don't use any electricity at all (which I am sure nobody does). On top of that, most poeple pay a certain rate for peak and, with some providers, a cheaper rate for off-peak usage. Currently the standard all-day rate for electricity from renewable sources (which we use) is about 0.25 Euro per kWh. No other surcharges or anything. Of course there are different contracts with different rates (pre-paid, certain "flatrates" up to a specific amount, etc.), but those are not the norm.

    Coming from 38 kWh per 100 miles real world usage would get me to around 24 kWh per 100 km or 6 Euro per 100 km. At 1.45 Euro per liter Diesel and about 6.5 liters per 100 km with our current cars that would equate to around 9.50 Euro per 100 km. So if the 38 kWh per 100 miles is really realistic it would mean the Model S would save me roughly 3.50 Euro per 100 km or 3,500 Euro per 100,000 km, which is the amount of driving I do in about 10 years. Not spectacular savings, but not bad either.

    - - - Updated - - -

    Regarding the cellphone, actually I have an old non-smartphone Nokia from a time where you actually used to use your phone until empty / nearly empty, then charged it full again. As I am still on the first battery after more than ten years and that battery still lasts almost forever, I don't think I "mistreat" my phone (I don't use the phone a lot, mostly it is just sitting on my desk / in my pocket for use in an emergency. Note that this thing is still more or less just a phone - ok you can listen to radio/mp3 and take a few pictures here and there - but other than that you can only use it as a phone / sms device). I know I'm a little old-school in many respects, don't use facebook, twitter et al. either. So there...

    About the energy usage. Yes, I am closely monitoring our daily usage of electricity (and water), at least I have done since I own a house and have a family. Must be in my genes, I work in controlling after all ;-)

    What I find most intriguing about the Model S is the question what it actually uses, losses included.
    For example my typical commuting workday looks like this: I drive about 5 miles to the nearest train station. From there I take several different commuter trains into Frankfurt (about 1.25 hour trip one way). The car is sitting there all day (no way to recharge there). In the evening I return by train to my car, drive home the last 5 miles. Then the car sits in the garage over night until the cycle begins again the next morning. At the weekend I do return trips to friends and family between 100 and 1000 km each. 1000 km trips are quite rare though. Most trips are under 400 km full circle.
    Anyway, with my current car sitting idle at the roadside for about 9 to 10 hours each day (which would happen to the Model S as well), with no possibility to "fill her up" during that time, I ask myself how that would affect the battery of a Model S and my electricity usage, especially during times like now, with sub-zero temperatures and snow all day long. I guess the "vampire load" would be quite high. Hence the amount I would have to recharge each night would be far more than what would actually be needed for a 10 mile drive under "normal" conditions.
     
  16. AP, I just finished a test weekend with a Nissan Leaf. I live up on the Alb at 824m. We had -10 deg. C this weekend. The Leaf used nearly exactly 30 kWh / 100 km for the 255 km I drove it from wall to wheel. Range at these conditions with the heater at 19 deg. was down to 95 km from the 160 km advertised. I'm really disappointed that all those critics where right. :(

    Just saying that you should AT LEAST calculate with 30 kWh / 100 km during winter.

    At my current rate at 0,25 ct / kWh a Leaf would have only marginally lower operating costs than my >200 PS AWD diesel. And guess what's more fun to drive ...
     
  17. bellwilliam

    bellwilliam Member

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    surprised that Germany electricity is that cheap.... about 30 cents/kwh.
    I am in SOCAL with Southern California Edison. easily the worst of all in USA. I paid ~32 cents/kwh.
    there are options like TOU (time of use), but summer day rate becomes ridiculous like ~60 cents/kwh. or I can add 2nd EV meter, but installation is ~$2,000. plus it is still close to 15 cent /kwh (it is 12 cents, but add basic cost).
    so for me. EV is equivalent of a ~35mpg car.
     
  18. ElSupreme

    ElSupreme Model S 03182

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    Well all of the USA except Hawaii. I am pretty sure they pay more than anyone else. I imagine that some parts of remote Alaska are also pretty bad.
     
  19. kendallpb

    kendallpb Model S: P 8061

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    #19 kendallpb, Feb 25, 2013
    Last edited: Feb 25, 2013
    Well, as I wrote, "most these days, methinks." Key words being "most," "these days," and "methinks." ;-) Sorry, it doesn't apply to your older phone (I haven't had one like that in years, but I remember that battery type, that is best discharged fully), but it does show how the phone-car analogy breaks down easily. :crying:

    I've only had a few nights like that but I still didn't lose a ton of juice overnight. I lose a little even in above-zero temps, but not much. I presume they'll fix the sleep mode at some point...hopefully soon.
     
  20. Rodolfo Paiz

    Rodolfo Paiz P85 "Plug and Play"

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    I'm still trying to get FPL in Miami to introduce a TOU tiered pricing structure, but at an overall (fully-taxed and all-inclusive) price of $0.12/kWh I'm not complaining. Roadster and Model S both make our ICE cars look like gas-guzzling dinosaurs who are very expensive to feed.
     

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