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40A charging - miles per hour?

Discussion in 'Model S: Battery & Charging' started by wamochi, Nov 15, 2016.

  1. wamochi

    wamochi Member

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    hello, pardon my lack of electrical knowledge ...

    we had a 2014 S60 that we charged every night in the garage. 40A got us about 29 miles per hour

    now we have a 2016 P90D that i've checked to make sure is pulling 40A and it's only getting about 25-26 miles per hour. i don't know if the volts have a lot to do with it, because i didn't compare the volts before/after ( although i might have some screen shots from that app in the early days i could go back to). but the app showed 231v last night.

    in any case, last night i started charging earlier just to watch it get up to speed and it took quite a while to climb up to 25 miles per hour and eventually maxed out at 26. is that normal?
     
  2. mal_tsla

    mal_tsla Member

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    This is because your P90D consumes more watts per mile than your S60. The same 40A/240V power is going into your car, but it is good for less miles than it was in the less powerful vehicle.

    Of course, that's just an approximation, because you can choose to drive that P90D slowly like you would an S60, and then the power that went in would be good for almost the same number of actual miles driven.
     
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  3. mal_tsla

    mal_tsla Member

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    The charge ramp rate depends on many many factors, so I won't speculate, but it is probably normal for whatever situation the car was in
     
  4. wamochi

    wamochi Member

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    thank you. i realize the wh/mi is higher on the P90D than the S60, but i did not realize it affects the # of miles per hour being sent back to the battery during charging?

    if i used 29 rated range miles on either car (let's say, for example, i drove only 20 actual miles on the P90D vs 23 actual miles on the S60), does that affect the replenishment of the 29 rated range miles in the battery? not sure why it would take a different amount of time to fill up the same number of rated range miles ... am i missing something?
     
  5. TexasEV

    TexasEV Well-Known Member

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    If you had a souped-up performance ICE it would go fewer miles on a gallon of gas. So why wouldn't you think a faster accelerating EV would go fewer miles on a hour's worth of charging at the same amps?

    Charging doesn't send "miles per hour" to the battery. It sends energy, measured as kWh. If you use more watt hours per mile, you'll get fewer miles from the same number of watt hours.
     
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  6. Xminus6

    Xminus6 Member

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    My 40a EVSE charges my car at around 29mph.
     
  7. NOLA_Mike

    NOLA_Mike Grouchy

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    Think of it this way.

    Your connection is providing about 9.5 kW of power to charge. Let's say that's 9.5 kWh for every hour you charge. Doesn't matter which car is plugged in, it is providing 9.5 kW.

    The Rated Range displayed in one car may be based on using 290 Wh/mile and the other car may be 310 Wh/mile. Therefore, for the same amount of time (one hour) one car may get 26 miles Rated Range and the other car may get 30 miles Rated Range. In other words, the same amount of energy is being sent to the car regardless of which car is plugged in - it's just that one car uses a different formula to calculate miles/kWh than the other car does.

    Mike
     
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  8. TexasEV

    TexasEV Well-Known Member

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    That's nice, but meaningless without knowing which car you have.
     
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  9. wamochi

    wamochi Member

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    ok thanks. i guess it makes sense. i just figured rated range is rated range, so i assumed the charge rate for RR would be the same.

    i've only driven about 2500 mi on the P90D and so far i'm looking at about a 10% overall increase in wh/mi vs. the S60. i don't tend to drive it much differently than the S60 since i'm usually just hauling my boys around :rolleyes:

    so are other P90D owners out there getting about the same 25-26 mph charge? (on a 240v NEMA 14-50)
     
  10. NOLA_Mike

    NOLA_Mike Grouchy

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    Also, you'd probably get about another 1 mile/hr bump if you were charging at 241V instead of 231V and it's possible you do get 240V late at night or early in the morning whereas you sag to 231V during heavy use times of day - that's not unusual in my experience.
     
  11. Rocky_H

    Rocky_H Active Member

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    It's based on the calculation from the EPA tests. The car goes a certain distance and uses a certain amount of energy to do it in the testing cycle, so that vehicle has an average watt hrs per mile number that is used to calculate the translation of % battery to rated miles. The 60 is more efficient than the P90D, and the Model X even less efficient than that. I've seen a few people who had gone from a Model S to a Model X and were also surprised at how they were getting lower "miles per hour" charging rate from the same connection they had been using.
     
  12. patrick40363

    patrick40363 Member

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    85D 30 miles per hour
     
  13. Xminus6

    Xminus6 Member

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    Classic 85. Why should it matter really? All our cars should be able to take as much amperage as any level 2 charger can supply.

    It was always my impression that the mileage added was a constant metric rather than dependant on your driving style.
     
  14. TexasEV

    TexasEV Well-Known Member

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    All take the same amperage, but that doesn't result in the same rated miles. That's what this thread is about. It has nothing to do with your driving style but it does depend on the car. Go back and reread the posts. A car that uses fewer watt hours/mile (such as a 60) will have more rated miles for the same kWh of added charge compared to a car that uses more watt hours/mile (such as a P90D).
     
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  15. Xminus6

    Xminus6 Member

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    I think a more useful measure would be miles charged per hour at 40a compared to lifetime consumption average then. You could find a more direct correlation than by car model.
     
  16. RobertF

    RobertF Member

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    2014, S85 with autopilot located in Huntington Beach, CA. 50 amp 220, 14-50. Use issued mobile connector at night (12pm - 6am). Get 26 miles/hr.
     
  17. Brass Guy

    Brass Guy Member

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    I'm gonna try a different analogy:
    You're not putting "miles" in your battery, you're putting kWh in; but the car is displaying miles anyway.

    If you consider ICE vehicles, if you put a gallon of gas into an econobox you may add 40 miles.
    If you put a gallon of gas into a guzzler you may add 12 miles; even though you still put a gallon in.

    "Rated miles" on one car are not always "rated miles" on another. If the EPA concluded the P90D is about 10% less efficient than your S60, putting the same power into the car gains miles 10% slower.
    You traded from one of the most efficient Model S to one of the least.
     
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  18. Max*

    Max* Banned

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    I don't think you understand.

    You know when you look at your classic S85, and look at the energy screen, you have a very faint "rated" line going across it AROUND 300 wh/mi, right?

    Well various models have the rated line at various places AROUND 300 wh/mi. The smaller batteries are rated closer to 280-290wh/mi, the larger batteries are rated closer to 310wh/mi.

    That RATING difference (EPA), is what causes the same ~9.6kW that goes into your battery at 40A to show up as different RATED miles being given back to the battery.

    It has nothing to do with consumption. I can drive the S60 like I stole it, and my lifetime wh/mi could be 500. Or I could draft the P100DL and have a lifetime consumption of 250wh/mi, but when I go charge either car at the same kW rate (in essence the same kWh for a given hour), the S60 will show it charging at a faster rated miles rate.
     
  19. Rocky_H

    Rocky_H Active Member

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    THIS. This is perfect--very well put.
     
  20. Racerx22b

    Racerx22b Member

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    2015, S85 with autopilot located in West Palm Beach, FL. 50 amp 220, 14-50 with HPWC plugged in and set to 40 amps. Charge it whenever the F I feel like it. Get 30 miles/hr.
     

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