Why can't I get 8.8kwh miles?

Discussion in 'Prime Main Forum (2017-Current)' started by SydneyNJ, May 30, 2019.

  1. SydneyNJ

    SydneyNJ Junior Member

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    I have a 2018 Prime Advanced. The multi-display instrument panel (MIP) says "5.1miles/kwh".
    Somewhere in the manual, it says 8.8kwh battery capacity. When I full charge this
    traction battery via L2, I always see 35.1miles for using pure EV or 34.x with Fan/AC on
    my MIP.

    Why can't I get 44.88 miles per charge (5.1mi/kwh x 8.8kwh)?
     
  2. schja01

    schja01 One of very few in Chicagoland

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    The portion of battery capacity for EV mode is closer to 6.1kwh. The rest is dedicated to HV mode use. The total is 8.8 Kwh.
     
  3. jb in NE

    jb in NE Senior Member

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    To prolong the battery life, the full capacity of the battery is not used. A typical full recharge from 0% indicated is 6.6 KWh.
     
  4. SydneyNJ

    SydneyNJ Junior Member

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    So when I charge, am I just charging ~6.1 - 6.8kwh of electric power or the full 8.8?
     
  5. john1701a

    john1701a Prius Guru

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    The battery will never be empty. At most, about 72% is added back each recharge.
     
    #5 john1701a, May 30, 2019
    Last edited: May 30, 2019
  6. Trollbait

    Trollbait It's a D&D thing

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    With no EV range left, a charge is only adding @6kWh.
     
  7. SydneyNJ

    SydneyNJ Junior Member

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    So if I want to know how much ($$) I am paying per charge (roughly), is the math:

    72% of 8.8kwh x $0.11 ?

    11 cents per kwh is my electric rate.
     
  8. SydneyNJ

    SydneyNJ Junior Member

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    or is the math:

    (1kwh/5.1mi) x ( 35.1mi) x ($0.11/kwh) ??

    35.1 is what i see on my MIP and the other numbers are just specs/facts.
     
  9. bisco

    bisco cookie crumbler

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    the cost is 11 cents times 6 = 66 cents per charge, roughly, depending on how low your battery is when charging

    the number of miles per kwh has nothing to do with your cost per charge.

    that would be useful for cost per mile if you're interested

    however, to be sure your kWh charge is correct, include all costs on your bill related to anything over the minimum monthly charge, if there is one.
     
    #9 bisco, May 30, 2019
    Last edited by a moderator: May 30, 2019
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  10. mr88cet

    mr88cet Senior Member

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    5.1 miles/KWh is quite good, BTW. I’ve been seeing — long-term, including bouts with high and low temps — 4.6 miles/KWh.

    A Tesla Model 3, which is considerably pretty efficient EV gets only around 3.8ish miles/KWh, and the Jaguar iPace, widely acknowledged as dreadfully inefficient, gets something like 2.5 IIRC.

    Anyway, I haven’t read the rest of the replies, but short summary, they reserve a 10-15% “top margin” to reduce the overcharging that can kill battery life, plus around 1KWh at the bottom is reserved for HV operation (and margin).
     
    #10 mr88cet, May 30, 2019
    Last edited: May 30, 2019
  11. SydneyNJ

    SydneyNJ Junior Member

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    Is this what you've been noticing on your electric bill? :)

    Well, I guess knowing exactly how much you pay on the bill is nearly impossible unless you have a dedicated circuit.
     
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  12. bisco

    bisco cookie crumbler

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    not exactly
     
  13. bisco

    bisco cookie crumbler

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    the bill only shows total kwh used by the whole house. individual circuits aren't tracked.

    you would need a kill a watt meter plugged into your outlet, then plug your evse into that. it would tell you what you are using, minus losses from the panel to the outlet.
     
  14. fuzzy1

    fuzzy1 Senior Member

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    You can put a kWh meter on you charger and get a real number.
     
  15. SydneyNJ

    SydneyNJ Junior Member

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    I'll take the guesstimate of $0.11kwh x 6.x kwh :)
     
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  16. bisco

    bisco cookie crumbler

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    that's what i do
     
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  17. jerrymildred

    jerrymildred Senior Member

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    If you want to track how much electricity you're actually buying for the car, there are plug-in meters like the Kill-A-Watt that will track it.

    As others have said, Toyota won't let the car completely fill or drain the battery. That would kill your traction battery in short order. If you're getting 35 miles/charge, you're way ahead of the EPA estimates (25 miles) and doing average to a little above average for most Prime owners. Before the Florida heat set in, I was getting 5.5-5.8 m/kWh. Now that the air conditioner is working overtime, it's just above or below 5.0. Not quite getting 30 miles/charge anymore that it's unbearable outside. It was at least 35 miles.
     
  18. SydneyNJ

    SydneyNJ Junior Member

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    hhmmmm... do you have a picture of this thing?
     
  19. fotomoto

    fotomoto Senior Member

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    There are charging inefficiencies from both the cable (EVSE), the charger itself inside the car and the battery. There's also the BMS (battery management systems) and the TMS (thermal management system) that regulate both the charge rate and the temperature of the pack which also requires some electricity so......

    as previously stated, you need some sort of measuring device (killawatt typically recommended) to see exactly how much energy is require to "fill the tank". High tech EVSE's will report the full charge amount via an app.
     
  20. jb in NE

    jb in NE Senior Member

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    Here is a snap from Amazon C3397541-469E-44B4-AD1A-A75664E6FDB2.jpeg
     
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