Variance in EV range estimates

Discussion in 'Clarity' started by Front Row, Jul 11, 2018.

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  1. Front Row

    Front Row Member

    Hi, New to the forum, I bought about 3 weeks ago, 1000 miles and only 3 bars from the dealer's fuel tank. Had to use the ICE the first weekend, but still haven't been to a gas station.

    Here's my question for you experts. I charge at night (on TOU at So. Cal. Edison) and range starts in the morning at about 50 miles. I drive the 17 miles to work and at the office the range says 40 miles left?? I drive the 17 miles home and when I get home range says 18 miles left??

    So round trip is very close to accurate but one ways vary greatly?!?!? Driving conditions the same both ways, moderate traffic, freeways, temps about the same. No real altitude changes. Any ideas why this variation?
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  3. Kendalf

    Kendalf Active Member

    My guess is that there is some slight but constant elevation in your commute. I experience something similar. My home is up by the 210, while work is down by the 60 fwy, and there is a gradual decrease in elevation much of the way down to work. I start with 55 miles range and arrive at work with 45 indicated after a 17 mile drive. Coming home I end up with something like 23 miles remaining.

    Does the car still indicate 40 miles remaining when you leave work in the afternoon?
    jdonalds likes this.
  4. Mark Miller

    Mark Miller New Member

    Your phone GPS should give elevation, find the elevation difference, and potential energy = m*g*h = (mass of car in kg)*(9.8 m/sec^2)*(elevation difference in m), then convert from joules to kWh. You should know what the energy range is for your battery, express this as a fraction of that. See if that explains some of the difference.

    Then, try keeping careful records of temperature for your morning/afternoon commute for a week or longer. Are you using AC for part of the drive? Same amount both ways?

    You should be able to chase this down. Report back!
    neal adkins likes this.
  5. KentuckyKen

    KentuckyKen Well-Known Member

    I find the EV range estimate to be within a 1-3 miles of the odometer reading if I use it up almost to 0 Ana if my driving stykeband conditions are steady.
    However I have noted that the charge bars don’t seem to reduce in a linear fashion. I lose bars slowly at the top and faster at the bottom
    The best way for you to try to track this down would be to charge at work and at home and see how many kW it takes each way and compare that to the milage from trip meter (has tenths of a mile odo doesn’t) and decrease in EV range. Remember the EV range is just an estimate based on recent driving and SOC of the battery.
  6. Clarity Dave

    Clarity Dave Member

    Interesting. By my calculations, that means for every 1,000ft (300m) of elevation gain the Clarity loses about 5 miles of range. One can then get much of it back with 1000ft of loss, depending on the efficiency of regeneration.

    Using Mark's formula above: (4052lb / 2.2 kg/lb) * (9.8 m/sec^2) * 300m * 2.7778e-7 joule/kWh * 3.3 mi/kWh = 4.96 miles

    One could add weight for passengers and payload to the above and quibble with the miles/kWh rate.

    That number makes sense to me based on a day trip, about 35 miles each way, starting at 1,500' and reaching 5,000'. Most of the elevation gain was in the last quarter of the trip. Starting with a full charge, our Clarity had to switch to HV mode for the last mile up. On the return, I was able to keep the ICE off while generating about 13 miles of EV range on the way back down which I then used up before reverting to HV mode for the last few miles back.
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  8. Front Row

    Front Row Member

    Whoa, is that math? It looks like math to me. I don't do math, I had to use a calculator to figure out 50-17 does not equal 40!

    There is a 300 foot elevation difference, and I think the traffic is a bit worse in the mornings.
  9. jdonalds

    jdonalds Well-Known Member

    I agree with others. It sounds like a small elevation change. Our drive to church first involves a 1/2 mile 14% downgrade followed by an almost imperceptible elevation drop of a couple of hundred feet. There are days when I'm 4 miles from home and my EV range estimate hasn't changed since we pulled out of the garage. Then on the way back we pay the price.

    The other factor is our summer heat which robs about 2 EV miles of range for every 15-20 mile trip.
  10. Carro con enchufe

    Carro con enchufe Active Member

    There’s a 3.5 mile section of my commute that seems pretty level to me. Yet it must have an almost imperceptible incline, as when I go down 3.5 miles I end up regenning all of it so I have the same range at the end. I’m sure I pay the opposite direction

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