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Electricity bill shocker

Discussion in 'Model S: Battery & Charging' started by caps04, Aug 7, 2015.

  1. caps04

    caps04 Member

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    I got a scary electric bill and started digging around the numbers. It seems I've used 4090kWh over 2 months for about 4000 miles of driving. 99% of which was charged at home.

    Now I need to dig into my old bills to figure how much out of the 4090kWh I should have expected to use without Model S charging. At least in terms of dollars spent, it seems about a 2.5x increase. So $650 instead of $260 I would've expected to pay over two summer months. If that's actually true, this car is costing me a little more to run than what a gas car would do (~10 miles to a dollar). I am paying about 16c per kWh and our usage patterns haven't changed in years.

    Will update when I do some more digging but I am wondering if this could be a faulty meter issue.
     
  2. liuping

    liuping Active Member

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    Check to see if your utility has a better rate for off peak charging. Many do and that can be significantly cheaper charging.

    4000 Miles is probably close to 1500 kWh, so it should be about $240 for the Tesla.
     
  3. commasign

    commasign Active Member

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    Are you on a usage tier model or is the per kWh price the same regardless of usage? Here in California on standard residential rate, the price per kWh jumps up significantly the more you use.
     
  4. caps04

    caps04 Member

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    Thanks. So if I used up around 2590 kWh (4090-1500) last June+July, then I guess the meter is correct.

    - - - Updated - - -

    The rate code is the same (June bill was an estimate) but the rate seems to have increased slightly in August. Not sure if it's usage tier model or not.

    elec_bill.png
     
  5. Saghost

    Saghost Active Member

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    That's not a tiered bill. If it were, you'd see "first 500 kWh at $.13 per kWh, second 500 @ $.25 per, etc.
     
  6. liuping

    liuping Active Member

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    It does not look like a tier usage model, since they have to break down the rates and amount for each tier. Yours looks like a straight 0.163458 per kWh.

    If you used 2590kWh last June-July, wouldn't your bill last year have been closer to $387 than $260? ($0.149614 * 2590kWh = $387.5).
     
  7. siai47

    siai47 Member

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    You need to see what your real consumption is. You have a starting June estimate (as you noted) but you also have a July ending estimate. Who knows what you really used. The rate change also messes it up but you need to concentrate on actual KWH used over a specific period. Loads changes a lot over summer periods with variable A/C loads. If you really want to know what your Tesla is costing you, get something like a TED 5000 energy monitor and monitor the power consumed by your EVSE.
     
  8. caps04

    caps04 Member

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    Sure but I don't think it was - unless electricity rates have massively shot up. Before the Tesla, I remember never paying much more than $110-130 at most. And that's why I suspect something is not right about this bill or the meter. Model S shouldn't cost me more than a 30MPG gas car. Anyway, will report back after digging through old bills.

    - - - Updated - - -


    Real consumption IS 4,090kWh. It's Actual, then Estimate, then Actual.. so the in between estimate doesn't matter. But obviously that doesn't include non-Tesla consumption and getting an energy monitor is the best solution. But before going through all that, there's no harm in doing some preliminary investigations. If everything looks in the correct ballpark, I won't have to bother.
     
  9. brucet999

    brucet999 Active Member

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    Your rate went up 1.25 cents per kWh from July to August. It has probably gone up considerably more since a year ago.

    Don't forget, when trying to estimate electricity usage, that Tesla on-board chargers are rated at 92% efficient, so AC power usage at the charge port will be 108% of what the battery receives without considering any losses in your internal house wiring, which could account for as much as 2% additional line loss before it gets from the meter to the Tesla charge port.
     
  10. Spurkey

    Spurkey P04251

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    Wow. My Internet-armchair-mathematician calculations point to a faulty meter. Of your 4090 kWh, say that 75% of them went into your car

    4090 kWh * 75% = 3067 kWh

    You have the 85 kWh pack:

    3067 kWh / 85 kWh = 36.08 fill up charges

    36.08 fillups * 200 miles per fillup = 7216 miles

    I underestimated the range to be 200 miles per fillup and this still comes out to way more miles than you actually put on your car. You either: 1) drove with an extremely heavy foot, only getting 110 miles out of your pack 2) are lying to us and you're running a fly-by-night piano moving/gravel hauling service and carrying obscenely heavy loads 3) your electricity meter is screwed.
     
  11. DFibRL8R

    DFibRL8R Member

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    If you don't like your electric bill, consider some solar panels if you have a decent roof for them. I enjoy paying my power company only $6 a month (grid connection charge).
     
  12. KJD

    KJD Member

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    Like someone else already said. Get a TED 5000 and find out where the juice is going first off.

    Depending on your house and the weather, it could be your air conditioner or some other house hold appliance is sucking up the juice.
     
  13. yobigd20

    yobigd20 Well-Known Member

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    heh my house in NJ was 2300sqft and just my central A/C unit alone could shoot up electric bill up past 3000kWh/month during the summer months. 4000kwh doesn't seem too abnormal IMO but I would bet it's more your A/C unit than the car. I drive between 3500-4000 miles per month and in general my electric bill went up about $150-$200/month on average. (significantly cheaper than the $700/month in gas I was paying per month prior to the Tesla). That was also about 0.18/kWh total for supply and distribution. honestly if you pay $650 for TWO months thats pretty good IMO because my MONTHLY is between $450-$700.

    - - - Updated - - -


    NJ doesn't have TOU, at least not around me -> ACE

    - - - Updated - - -

    also that picture pretty much proves that they estimated wrong. july was estimate and august was actual. they estimated you'd use 1200kWh in july when in august they got the difference from the estimate to actually at 3400. so in reality your july bill probably used around 2000kwh, not 1200kwh, and your august bill probably used around 2000, not 2800. therefore your july bill if it was actual would have been higher, and your august bill would have been lower. in the end though you're right, both together was over $600 and in my opinion i would have killed to have two molnths only total $600 lol
     
  14. Soolim

    Soolim Member

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    For the moment, let us assume that OP memory of paying $130 per month for his electric bill is accurate. Using an average rate of say $0.15 per kWh means his normal (pre-Tesla) consumption is 867 kWh per month.

    Hence, Tesla consumption in two month is 4090 - 867 - 867 = 2356 kWh. At 320 Wh/mile, this is equivalent to 7362 mile. This is much higher than the 4000 miles OP recorded.

    From another point of view, 4000 miles at 320 Wh/mile = 1280 kWh. So there is a mysterious 2356 - 1280 = 1076 kWh consumption or loss in 2 months or roughly 538 kWh per month.

    Could it be that OP home electricity consumption has risen due to hot summer with the home A/C. Or his neighbor is charging their MS on his charger:confused:
     
  15. caps04

    caps04 Member

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    I wish I could. I live in a tiny townhouse with barely any roof and our association probably doesn't even allow it.
     
  16. caps04

    caps04 Member

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    Ok, so I dug up last year's consumption numbers and it's 650 + 1200 kWh for those two months. Assuming the non-Tesla consumption did not change, the car is sucking up 2240kWh (4090-1850) for 4000 miles. Even if I get 200 miles per full charge, the car shouldn't be using 112kWh (2240 / (4000/200)). I do keep the car plugged in whenever I'm home but still.

    Clearly something is wrong. Here are the possibilities (from impossible to most likely):


    • Model S is not as efficient as claimed - impossible. I know there are losses involved in charging and vampire loss, etc. but it can't make that big of a difference. Besides, no one else is seeing such numbers.
    • I drove much more than 4000 miles - unlikely. I probably drove a bit less than 4000 miles but rounded it up.
    • My car charger/battery is defective - unlikely but will get TED 5000 to verify
    • My AC or home insulation deteriorated since last year - possible
    • My non-Tesla consumption changed vs last year - likely but need to investigate
    • The meter is defective - possible

    Anyway, I guess I need to get TED or something similar to monitor my usage. Any recommendations for a device preferably with an iOS app and remote access?

    Thanks for the input everyone.
     
  17. Kipernicus

    Kipernicus Model S Res#P1440

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    Was this summer warmer than last summer, and you are using the AC more?

    Now I appreciate my PG&E smart meter more. We can log into our account on the web and get usage stats (and cost) by hour, for as recently as the day before.
     
  18. Saghost

    Saghost Active Member

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    Pretty sure you're having a much hotter summer than last year - and since you identified A/C as a major part of your consumption already, it likely became a bigger piece.
     
  19. jerry33

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

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    My highest electric bill this year was under $150, and it's been pretty hot here in Texas.
     
  20. Saghost

    Saghost Active Member

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    Apples and oranges. Different billing plans from different utilities, different house sizes and insulation - no way to draw any useful conclusions from that. :)
     

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