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Model 3 Charging cost? - Significant increase in Electric bill

Discussion in 'Canada' started by Djnas786, Aug 3, 2018.

  1. gavine

    gavine Petrol Head turned EV Enthusiast

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    Better to charge every morning which happens to warm the battery anyway and thus allows for regen which, unless you get on the highway immediately, could add-up to a lot of net energy savings, especially if you have a lot of stop-and-go and/or traffic lights.
     
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  2. VistaM3B

    VistaM3B Member

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    I believe with 120 km/day Ontario Winter driving you loose around %30 - %40 per day. With the assumption that you leave in the morning with %80 and coming back home at %40-%50 left.
    Option #1 - Charge every night to 80 percent (start at 7 P.M) --> battery is already warm, charges faster- less electricity bill but limited regen in the morning.
    Option #2 - Charge every night to 80 percent and schedule it to finish at 7 A.M. (battery will be cold at charging start time)--> charges slower, more electricity bill but you have the regen when you leave to work in the morning (battery is warm).
    -Charge your car when the battery is already warm (Solid line or with minimum dots) this rule applies to super charging as well.
    Tesla Charging recommendation %20-%80 does not practically work for Ontario Winter driving/charging but in summer.
    With 95 cents a litre I put more mileage on my gas car in extreme cold weather and/or slushy roads than my M3.
    I hope this helps.
     
    • Like x 1
  3. ben1628

    ben1628 Member

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    Another reason why I plan to keep my AWD with snow tire ICE car around for those extreme weather.

    My M3 will be on all season. When it’s too cold or snowing moderately heavy ICE would be my choice.

    The good thing about GTA roads is the snow get cleared pretty quickly and my M3 will be back on road. Nothing beats AWD with snow tire when it snows.

    I’m not here to decide which car is better, just trying to enjoy life safely
     
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  4. Evoforce

    Evoforce Member

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    M3 is is the safest car on the road with some snow tires and AWD you don't need ICE.
     
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  5. gavine

    gavine Petrol Head turned EV Enthusiast

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    Having regen should make up for the extra energy needed to warm the battery for charging, unless the commute is all highway where regen isn’t used anyway. Regen might even be a net positive with less total electricity use. I’m thinking the brakes emit more total heat than the battery warmer uses.

    Heck, Tesla uses stored battery energy to warm its own battery in order to enable regen (when range mode is off). It must be worth it.
     
  6. SSedan

    SSedan Active Member

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    But the car doesn't know how far you are driving. It presumes each trip is long, plus the frequent heating every time you drive stops it from falling to ambient temps.
     
  7. darkenergy

    darkenergy Member

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    Rather than pontificating, here are some measurements.

    My goal here was to get a sense, in bulk, of the steady state energy used while the car was just sitting overnight. So this should include losses from any vampire drain, battery warming, inefficiencies in the EVSE and charger, etc.

    The energy tracker here is a TP-Link HS110 smart plug. Third party checks call it out as being about +/- 5% accurate on the measurements. Which is sufficient in my book for a sanity check.

    Conditions:
    • Model 3, LR RWD, (Mftr: May '18)
    • Parked in a garage for 1 week, no driving
    • Garage temperature (approximately 6C (10am/10pm))
    • Car set to charge to 80%
    • Charging limited in car to 10A @125V
    • Power turned on at the socket 7pm to 7am, off during the day.
    • 2018.48.1

    Total 7 day draw, including 3rd party EVSE: 10.4 kWh

    So, at Toronto Hydro overnight rates, that's about $ 0.676 per week, or about $12 for the winter.

    So from a cost perspective I'm giving this a massive <shrug>

    Of more interest to me is the question of whether lots of small charges is better or worse than infrequent top-ups along with cold temps.

    ymmv. Or should that be ykWhmv ?
     
    • Informative x 3
  8. MP3Mike

    MP3Mike Well-Known Member

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    That is about double what I would expect. Do you have any third party apps linked to your account that would keep your Model 3 awake?
     
  9. darkenergy

    darkenergy Member

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    No third party apps, and I reset my account password recently.
     
  10. darkenergy

    darkenergy Member

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    Although having it percolate in the back on my head for a couple of hours, I'd guess it might be on the high side if the measurement device is more inaccurate with lower current draws. Which would be most of those 84 hours.
     
  11. ben1628

    ben1628 Member

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    Oh, I have the exact TP-Link switch sitting around doing nothing, may use it to monitor it as well.
     
  12. SSedan

    SSedan Active Member

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    If you charge daily you get the battery to warm off of shore power rather than additional discharge cycling of the battery.

    The pack does not fully chill to ambient in 10 hours in my observation.
     
  13. swotam

    swotam Member

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    Not sure how much value this adds to the overall conversation, but in general I haven't seen a substantial increase in my electricity use since getting my Model 3 on Dec 4 (the middle of the chart). I live in Milton, Canada so this shows off-peak (7pm - 7am) usage which is when I charge the car. Note that weekends are considered off-peak, so they represent noticeably higher overall usage.

    I typically drive 20-30 Km per day, so charging at 32 amps usually takes 30-40 minutes. The most I've had to add overnight at home has been 22.5 kWh, which took around 3 hours. If you look at the two weeks before Dec 4 vs the two weeks after, the increase is not huge.
    Screen Shot 2018-12-21 at 10.33.28 AM.png

    Below is an example of my daily use on Dec 19. I added 33 Km / 4.8 kWh to the car that evening after 7:00 pm. My total off-peak use on Dec 19 was 13 kWh, so the vehicle represents less than half of daily off-peak use. In general, I'm expecting my electricity bill to go up by a reasonable amount each month, but that amount is more than offset by not having to pump $100 worth of gas into my old ICE car during the same period.
    Screen Shot 2018-12-21 at 10.45.52 AM.png
     
    • Informative x 1
  14. mswlogo

    mswlogo Active Member

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    No, regen does not make up the difference you use to warm the battery. Don't warm the battery just to get regen.

    Charge when it's cheapest and warmest battery.
     
  15. gavine

    gavine Petrol Head turned EV Enthusiast

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    Why does the Tesla BMS warm the battery using battery energy while driving? It continues to do that until a good amount of regen is available, then it stops. I don't see any other reason to do this unless the potential regen is net positive. I'm not being confrontational, I'm genuinely curious.
     
  16. gavine

    gavine Petrol Head turned EV Enthusiast

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    This one is a little confrontational....what if you live at the top of a mountain? Would warming the battery for the sake of regen make sense then? I guess my point is that "it depends" and you said it as if it applies 100%.
     
  17. TesSpartan

    TesSpartan Member

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    This is what I have gleaned from this post:

    Since my cheaper electric rates don't coincide with my drive home, and since the battery needs to be heated to charge it, my advice is to only charge it 3 days per week if possible.
     
  18. bijan

    bijan Member

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    How do we know this? I thought battery warms through heat generated by motor working normally and charging on limited regen, not necessarily extra energy specifically for battery warming.
     
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  19. mswlogo

    mswlogo Active Member

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    Your Tesla's have no brakes either? The more you can use regen (like on a mountain top) the faster the battery will warm up from (low regen). So it's not as if you'd have no regen the whole way. If it's not long enough to warm it up, it wasn't much lost regen in the first place.

    People think so binary here. They assume it's 0 Regen for an infinite amount of time. When 90% of the time it's low regen for some amount of time. And that time gets shorter and shorter the more regen is active.
     
  20. gavine

    gavine Petrol Head turned EV Enthusiast

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    When the battery is cold and you're stopped with the car in drive (HVAC off), the power meter will show about 5kW of power being used. That is, presumably, to warm the battery. Once about half of regen becomes available, the power meter will drop. What else would use 5kW just sitting still with HVAC off?
     

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