No, It’s Real: EV Range Down

Discussion in 'Prime Technical Discussion' started by mr88cet, Jul 12, 2018.

  1. mr88cet

    mr88cet Senior Member

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    Well, I originally thought it was just the Toyota Guesstimatron estimating low. No, it’s almost certainly a very-real and pretty-substantial range loss!

    I used to charge at work, ChargePoint saying that it put in 5.8KWh or so, typically, and I’d arrive home with a predicted 11ish miles left. Today, ChargePoint says it charged 4.8KWh, and if I had gone directly home, I most likely would have had only 2-3 miles left.

    So, it sure looks like either the batteries are depleting in some sense, or the charger is just refusing to charge them fully.

    My *best guess* as to what might be going on is that over the past couple months especially, although to a lesser degree before that, I have been doing considerably less scheduled charging. Instead, my wife and I have taken it up to the local mall, where we have quasi-free charging (and a pleasant walk together!), “filling ‘er up” there, and leaving it charged to 27ish miles over night.

    Still, I’m kinda finding that a little hard to imagine being the cause of a 8-mile range drop, over the past 3-4 weeks. That is, 4 weeks ago, it was still getting 30ish miles.

    The drop has been in two distinct steps, interestingly: 3-4 weeks ago, it dropped pretty suddenly from 30-31 down to 27-28, and then 5ish day’s ago it again dropped another 2 miles to 25-26. Very much a sudden, instantaneous drop in both cases.

    Waddaya folks think?

    I’m thinking my next move ought to be to go back to scheduled charging, mostly, for a few weeks and see if it recovers.
     
    #1 mr88cet, Jul 12, 2018
    Last edited: Jul 12, 2018
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  2. schja01

    schja01 One of very few in Chicagoland

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    Temp related?
     
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  3. mr88cet

    mr88cet Senior Member

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    Referring to outdoor temperature, I presume?

    Well, can’t say for sure, but it didn’t do this last summer.
     
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  4. bisco

    bisco cookie crumbler

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    definitely, depending on how hot it is.

    how many ev miles on her? seems to early for much degradation.
     
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  5. mr88cet

    mr88cet Senior Member

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    Especially degradation in two distinct steps.

    Highs here in the mid-to-high-90s F. If anything, last summer was hotter, and no such thing last sunmer.

    Little over 20K miles on it.
     
    #5 mr88cet, Jul 12, 2018
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  6. bisco

    bisco cookie crumbler

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    20k ev? could be some degradation involved, but that seems like too quick a drop. usually, it is more insidious.

    no range drop last summer with higher than 90's temps? that doesn't seem right either.
     
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  7. mr88cet

    mr88cet Senior Member

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    I at least don’t remember it dropping particularly noticeably last summer.

    So, you other folks who live in hot climates: Has your range dropped with increasing temperatures?

    Its 20K miles have certainly mostly been in EV mode.

    The fact that it has dropped in two distinct steps of 2-3 miles each ... well, that sounds a lot more like a computer making decisions than a battery electro-chemically degrading. (Actually 3 steps, but the first drop, from 34ish to 31ish was 3ish months ago.)
     
    #7 mr88cet, Jul 12, 2018
    Last edited: Jul 13, 2018
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  8. tpenny67

    tpenny67 Active Member

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    Very interesting. Is the Prime like the normal Prius in that it relies on cabin air to cool the battery? If so, reducing A/C use might lead to a warmer battery, which could conceivably limit the maximum charge level. You said it was hotter last summer, were you also using the A/C more possibly resulting in a cooler battery? Is this something you can monitor with a ScanGauge on the Prime?

    For what it's worth, the battery in my Gen3 in Massachusetts can get up to about 110 degrees after sitting in the sun in the parking lot all day. I've heard Texas is even hotter than MA :)
     
  9. schja01

    schja01 One of very few in Chicagoland

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    I found this (emphasis by me):
    2018-07-13_071934.png
    So it's more an estimate after A/C season begins.
    Those "steps" might be adjustments to the estimates?
    J
     
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  10. mr88cet

    mr88cet Senior Member

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    Thanks for the thoughts... Yes, the P.Prime uses forced-air battery cooling, where needed. That, pretty much always during charging, but pretty rarely while just driving.

    To clarify, the temperature difference between last summer and this summer is not huge, as far as I can tell.

    “ScanGuage” meaning an OBDII jobbie? It would be interesting to get a readout of the individual battery voltages. I bought a Carista a while back, but unfortunately, haven’t had a chance to try it out yet.

    I’m pretty confident that what I’m seeing here is not just greater air-conditioner usage, since, according to ChargePoint, it’s actually charging considerably fewer KWh into the battery.

    I’ve fairly consistently kept the A/C set at 80F since I got the car. That is, if the outdoor temperature is significantly above 80. If not, I just use forced-air cooling on myself!

    FWIW though, thankfully, it rarely sits in hot parking lots; almost everywhere I go routinely has covered parking.
     
  11. mr88cet

    mr88cet Senior Member

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    So, yes, thanks for the manual reference. Where is that in the manual? (I’d like to hear a little more context on that quote.)

    Again, I’m pretty confident that it’s not mostly a matter of greatly-increased energy consumption, or of its estimate going down. That, since the real range is definitely lower, and ChargePoint clearly reports charging considerably less. Historically, I’ve seen as high as a little over 6KWh per charge, whereas yesterday ChargePoint said it only charged 4.8KWh into the battery.
     
    #11 mr88cet, Jul 13, 2018
    Last edited: Jul 13, 2018
  12. fotomoto

    fotomoto Senior Member

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    That is the worst case scenario for an air-cooled battery: heating up a battery through use (morning commute), then charging L2 in the heat and then letting it sit (bake) in the sun.

    On our Energi's, this can trip the max. temp battery threshold of 113f when only hybrid (gas) mode can be used. Some of the first folks to discover this battery protection mode were drivers in Austin. Even though I live further south, I've never encounter it because I don't charge at work and only L2 charge in the garage (typically only at evenings/night). Most of our owners have lost at least one kilowatt or more capacity since 2013.

    The best way to determine capacity loss is to charge a cool battery, drive it to zero ev range on one drive, stop and record the kwh's used, and compare to new (factory specs).
     
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  13. Bob Comer

    Bob Comer Active Member

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    I live in Coastal South Carolina, and while we aren't quite as hot, we're in the 90's. I haven't noticed any drop in EV mileage. I keep my AC set at a lower temp than you do, 72-74F most times. (and all the time on, even in Winter.)
     
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  14. bisco

    bisco cookie crumbler

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    at 30-35 miles, it can go unnoticed unless you're really paying attention and recording performance.
     
  15. Bob Comer

    Bob Comer Active Member

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    I get ~30 miles at this time of year -- my commute isn't the best for EV mileage, it's mostly rural...
     
  16. mr88cet

    mr88cet Senior Member

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    Excellent info. Thanks.

    As I mentioned, my current guess, based upon my recent charging habits, is that Toyota’s charge management is seeing that I’m frequently keeping the battery overnight at nearly a full charge, and it’s therefore trying to increase the time-average top charging margin by not charging as high.

    Do you use scheduled, “just in time” in essence, charging more often than “charge now,” or the reverse?
     
  17. schja01

    schja01 One of very few in Chicagoland

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    I found it in the PDF version as I don't have my car (yet). In there it's in Chapter 2.1 Plug-in Hybrid System Page 100
    2018-07-13_084711.png
     
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  18. ETC(SS)

    ETC(SS) The OTHER One Percenter.....

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    This could be just instrumentation or environmental in addition to battery aging.

    This is probably a combination of all three.

    Back in the good old days when cars were all wireless, I used to see a lot of posts about the DTE in the G3 hatch.....which is a guesstimate that is biased by past performance....and people would be worried about their fuel efficiency slipping based on Toyota's guestimation.

    In the end....the only way you're really going to know if your battery pack is lagging a step or two around the bases is to measure it over a repeated course over a period of time, and following a known charge from a known source, and then?
    It STILL might not be the battery.
    You could be dragging a wheel from low tire pressures or an as-yet undetected brake, suspension, or alignment problem.
    It could be environmental.....like your HVAC system working harder to keep the inside of the car cool.

    Or?
    It could be a cockpit thing.

    Likely, it's

    D.) All of the above.
     
    #18 ETC(SS), Jul 13, 2018
    Last edited: Jul 13, 2018
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  19. mr88cet

    mr88cet Senior Member

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    Thanks for the thoughts!

    In my particular case at least, it rarely sits out in the sun; almost all places I go routinely (thankfully!) have covered parking.

    I’m thinking that’s true, but that it won’t adjust as rapidly as just one single charge cycle. I’ll probably have to change my charging habits for at least a week before the computer will react to them.
     
    #19 mr88cet, Jul 13, 2018
    Last edited: Jul 13, 2018
  20. mr88cet

    mr88cet Senior Member

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    Again, I’m pretty confident that it’s not just the estimate going down, nor greater power consumption, because ChargePoint has been reporting only charging ~5KWh into the battery (starting very close to the HV threshold), where it has historically reported charging about 6KWh.
     
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