1. Attachments are working again! Check out this thread for more details and to report any other bugs.

What is your miles/kWh (total average electricity consumption) on the "Drive Monitor 2"

Discussion in 'Prime Fuel Economy & EV Range' started by Salamander_King, Jun 4, 2019.

  1. Paul.Ivancie

    Paul.Ivancie Member

    Joined:
    Jul 3, 2013
    60
    53
    0
    Location:
    Upstate NY
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Advanced
    Thanks,
    That 3-4 figure being normal makes me feel a little better. I wasn't paying as close attention before, because I knew I could just punch it up when I wanted to. My lifetime average from my gasoline-only spreadsheet is now at 139 MPG, and I spent $12 this month on EV charging. Because of the Coronavirus, my EV miles driven this month will be about half of my normal 1200. So far, I have seen just a few days with numbers at 5 or above (5 days).
     
  2. Salamander_King

    Salamander_King Senior Member

    Joined:
    Nov 8, 2015
    10,958
    8,836
    0
    Location:
    New England
    Vehicle:
    Other Hybrid
    Model:
    N/A
    On my 2017 PRIME, I put 40K miles in 2.5 years and the lifetime average was 5.2miles/kWh. But this includes very intensive manipulation to increase EV efficiency in the last 8 months of the ownership. At the end of 2 full winters at ~30Kmiles, I had 4.5miles/kWh. If I did not change the way I drove, the number would have stayed at around 4.5 miles/kWh all the way to the end. The first 10K miles is easier to change the lifetime average, but longer you drive harder to change the average for the lifetime miles/kWh. I traded in 2017 Prime to 2020 Prime at the end of Feb. Since I now have only ~500 miles on my car, my DM2 miles/kWh fluctuate daily between the min 0 miles/kWh when I reset DM2 data to max 99.9miles/kWh. It is currently showing ~15miles/kWh. This is with EV/HV switching to maximize EV efficiency.

    Screenshot 2020-03-29 at 6.10.52 PM.png
     
  3. Salamander_King

    Salamander_King Senior Member

    Joined:
    Nov 8, 2015
    10,958
    8,836
    0
    Location:
    New England
    Vehicle:
    Other Hybrid
    Model:
    N/A
    Update on my 2020 PRIME. After 1000 miles on ODO, I am now recording over 20miles/kWh on the DM2 which was reset shortly after I purchased the car new. The car had 40 miles on ODO when I purchased it, but there was no record that it had ever been driven EV mode with a charged traction battery. All miles driven were accounted on the Eco log, but corresponding miles/kWh was all 0.0 indicating that no EV mode was used for those miles. Yet, DM2 was showing 5.3miles/kWh when I took the delivery. I have reset the DM2 to check if the number represents the base number where the record starts, but that was not the case. Immediately after the reset, the DM2 was showing 0.0 miles/kWh. So I don't know how initial 5.3 miles/kWh was generated without any EV mode drives.

    In any case, since then I have been trying to keep the EV efficiency high by using EV mode only in very low demanding portions of my trip, namely on downhill, flat road coasting, and very light accelerations. This has resulted in DM2 recording above 20 miles/kWh. However, my current GoM for a full charge is just slightly over 30 miles mark. If GoM is calculated simply from average miles/kWh, it should show much more than 30 miles, but it doesn't. What can be concluded is that the GoM must use other parameters besides just average miles/kWh. But I don't know what other parameters are???

    Screenshot 2020-05-17 at 7.02.20 PM.png
     
    benagi likes this.
  4. Bill Norton

    Bill Norton Senior Member

    Joined:
    Dec 15, 2012
    1,808
    591
    0
    Location:
    MONW, Ks.
    Vehicle:
    2010 Prius
    Model:
    Five
    Could it be the SW engineers used common sense?
    Maybe they thought using EV mode for only "...blah, blah.." would only be for photo Ops.:whistle:

    IF I only went downhill in my BEV I could have similar numbers displayed!;)
     
  5. Salamander_King

    Salamander_King Senior Member

    Joined:
    Nov 8, 2015
    10,958
    8,836
    0
    Location:
    New England
    Vehicle:
    Other Hybrid
    Model:
    N/A
    If I can put numbers and formulas on that common sense, then I will be satisfied with your answer. I am just curious how GoM mile is calculated internally in my car. That's all.

    In my current, ~50 miles per week driving and very low cost of gas (about 40% lower than electricity for the same distance), it is the best time to experiment those parameters.
     
    Bill Norton likes this.
  6. PiPLosAngeles

    PiPLosAngeles Senior Member

    Joined:
    Nov 18, 2012
    1,549
    719
    0
    Vehicle:
    2021 Prius Prime
    Model:
    LE
    Repeated this test yesterday and today. Yesterday was 6.45 kWh and today was 6.39 kWh. Not sure why the 6.45. Maybe it took a few seconds to shut off the car after it bumped to 0% on the EV, or maybe some extra cooling during charge? Looks like zero measurable degradation so far.
     
  7. Salamander_King

    Salamander_King Senior Member

    Joined:
    Nov 8, 2015
    10,958
    8,836
    0
    Location:
    New England
    Vehicle:
    Other Hybrid
    Model:
    N/A
    That's very good to hear. Since I traded in my 2017 Prime, I am starting out a totally new matrix. I plan to keep a record of kWh required for a full charge, unlike I neglected with my 2017 for over a year during my ownership. But currently, I am not driving my 2020 PRIME much, and I don't want the car to just sit with a full battery charge. I have charge my traction battery fully charged from empty only twice so far. Both times it took ~6.5kWh. I think the slight variation on the full charge amount comes from the amount of discharge after the traction battery reaches 0% before starting to charge and also the ambient temperature. But I don't have any hard data to support this theory.
     
  8. PiPLosAngeles

    PiPLosAngeles Senior Member

    Joined:
    Nov 18, 2012
    1,549
    719
    0
    Vehicle:
    2021 Prius Prime
    Model:
    LE
    Luckily I have a weather station that records data. I can fill in the outside temperatures for each recorded charging session if you think that might be a factor. The 6.45 kWh charge was overnight with an average temperature of 57°F, and last night's temps during charging were around 58°F.
     
  9. Salamander_King

    Salamander_King Senior Member

    Joined:
    Nov 8, 2015
    10,958
    8,836
    0
    Location:
    New England
    Vehicle:
    Other Hybrid
    Model:
    N/A
    That's too close. Maybe the battery temperature was different?
     
  10. PiPLosAngeles

    PiPLosAngeles Senior Member

    Joined:
    Nov 18, 2012
    1,549
    719
    0
    Vehicle:
    2021 Prius Prime
    Model:
    LE
    I do not know. It's an outlier considering my other charges were all 6.39. Ten seconds of A/C compressor could have done that.
     
  11. Salamander_King

    Salamander_King Senior Member

    Joined:
    Nov 8, 2015
    10,958
    8,836
    0
    Location:
    New England
    Vehicle:
    Other Hybrid
    Model:
    N/A
    I just did a full charge on my new PRIME today. The full charge took 6.92kWh measured by Kill-a-watt meter. I run out of EV range just a few hundred feet before pulling into my driveway yesterday, so I did not over-discharge the traction battery after EV range was depleted. This was probably the highest amount of kWh used for a full charge in my recollection. I really don't know what's going on.
     
  12. PiPLosAngeles

    PiPLosAngeles Senior Member

    Joined:
    Nov 18, 2012
    1,549
    719
    0
    Vehicle:
    2021 Prius Prime
    Model:
    LE
    I'm curious where I can take a good reading of the traction battery voltage. I'm willing to bet that the point at which the car goes from 1% to 0% isn't as precise as we're expecting.
     
  13. Salamander_King

    Salamander_King Senior Member

    Joined:
    Nov 8, 2015
    10,958
    8,836
    0
    Location:
    New England
    Vehicle:
    Other Hybrid
    Model:
    N/A
    I wish I had the Hybrid Assistant running the last time I depleted the EV range. If I did, I could tell what SoC the hybrid battery was at the time I parked my car.

    For the record, on 2017 Prime, the number of times I did check the EV range depleted traction battery SoC, it ranged from 10.2% to 14.12%, but this is not precise 0% EV as you have measured. A varying distance of HV drive after depleting EV range caused the variation. More interestingly, the 100% SoC on the dash corresponds to a much tighter range from 82.35% to 83.92% but did show some variability. Low mark on 0% and high mark on 100% might explain more kWh used for a "full-charge", but that's only speculation at this point.

    upload_2020-6-22_5-4-3.png
     
  14. jerrymildred

    jerrymildred Senior Member

    Joined:
    Oct 28, 2016
    11,490
    14,095
    0
    Location:
    Tampa, FL
    Vehicle:
    2017 Prius
    Model:
    Two
    Exact same same situation for me yesterday except using L2 at 16A. I reset my meter so it would measure Wh rather than kWh. Ran out of juice about 5-600 yards from home. Used 6,310 wH to charge. Not sure how much more it would have taken to run the fan and other equipment for five hours rather than two, but I could figure it out if I knew the current draw of the charger's cooling fan. I just looked at a desktop fan and it uses 35 watts. If that's typical for the charger fan, over three hours, it would make about a 100wH difference.

    If that's a reasonable approximation, I'm seeing a slight reduction in capacity from your new car, but no reduction in my capacity since I started tracking it at the start of this year.
    Screen Shot 2020-06-22 at 8.10.32 AM.png
     
    benagi and Salamander_King like this.
  15. Salamander_King

    Salamander_King Senior Member

    Joined:
    Nov 8, 2015
    10,958
    8,836
    0
    Location:
    New England
    Vehicle:
    Other Hybrid
    Model:
    N/A
    Aha! The cooling fan might be the reason for the increased kWh. Due to the COVID-19 situation, I am not doing nightly scheduled charging now. The car was parked over night since last driven on Sat, but for yesterday (Sunday), I just did the immediate charge by plugging in at 10:30am. I don't usually charge my PRIME during day. Yesterday high temp was 76F. Even though the car was parked in a shade I am sure the inside of the car was above 80F. Compared to this, our night temp even during hot summer is usually 50-60F and inside of car is as cool as ambient temp. As far as I can remember, this was the first time I charged my PRIME from zero to full during a summer midday.
     
    #235 Salamander_King, Jun 22, 2020
    Last edited: Jun 22, 2020
    jerrymildred likes this.
  16. PiPLosAngeles

    PiPLosAngeles Senior Member

    Joined:
    Nov 18, 2012
    1,549
    719
    0
    Vehicle:
    2021 Prius Prime
    Model:
    LE
    Since degradation is a fact of physics with Li-ion battery chemistry - and we're not seeing any measurable amount - I suspect that there might be some kind of "reserve" built in to the battery and/or the battery management. If I were designing a system to avoid customer complaints and warranty claims I would do precisely that. Initially the car would only be allowed to use something like 70% of the full 8.79 kWh capacity (6.15 kWh) and as the battery slowly degraded I would continue upping the percentage allowed to be used to maintain 6.15 kWh until reaching around 80%. That would allow for about 13% degradation that is completely hidden from the end user.

    It's not cheating, it's front-loading the degradation into the system from the get-go to manage customer expectations.
     
    #236 PiPLosAngeles, Jun 22, 2020
    Last edited: Jun 22, 2020
    Tideland Prius likes this.
  17. Salamander_King

    Salamander_King Senior Member

    Joined:
    Nov 8, 2015
    10,958
    8,836
    0
    Location:
    New England
    Vehicle:
    Other Hybrid
    Model:
    N/A
    Wouldn't that shows up on the SoC matrix on HA? At least for my 2.5 years of owning 2017 PRIME, the real SoC on the traction battery was always corresponding to 84% to 14%.
     
    jerrymildred likes this.
  18. jerrymildred

    jerrymildred Senior Member

    Joined:
    Oct 28, 2016
    11,490
    14,095
    0
    Location:
    Tampa, FL
    Vehicle:
    2017 Prius
    Model:
    Two
    I think what you say makes sense. I haven't tried that and I didn't get mine new anyway, but those are the numbers I'd expect. Here's why.

    If the BMS was using more and more of the battery to hide degradation, the degradation rate would increase and get very obvious once the reserve was gone. If the system continued to reserve the same percentage of the battery (which I think it does and your data supports), I'd think the rate of loss would be linear. What's interesting to me is that we seem to be seeing is a degradation over the first few years and then a reduction of that rate of degradation over the following years. I say "seem" because I don't think we have nearly enough data gathered in a controlled and scientific way.
     
  19. PiPLosAngeles

    PiPLosAngeles Senior Member

    Joined:
    Nov 18, 2012
    1,549
    719
    0
    Vehicle:
    2021 Prius Prime
    Model:
    LE
    That depends on how li-ion degradation manifests. If the cell voltages degrade over time then your hypothesis would be correct - the degradation would shop up on HA. However, if the voltages remains relatively constant while the capacity decreases, then the degradation is going to be hidden from any meter that relies on voltage.

    For example, say a brand-new fully charged traction battery is 380V (4V per cell), and running the battery down to 323V (3.4V per cell) yields 6.5 kWh. Now imagine it's 3 years and ~1,000 charges/discharges later and the battery still charges to 380V and discharges to 323V, but that only yields 5.85 kWh. The battery has lost 10% of it's capacity, but HA will measure the same voltage at "full" and "empty" as day one and have no idea that anything's changed.

    I don't think so. With a linear degradation of 2% per year (just for example), you would see no degradation for about 6 years and then see 2% each year thereafter. There wouldn't be a "jump" at any point. If the battery's true rate of degradation isn't linear, then all the better for my hypothesized strategy. In that case the first few years with the highest degradation are hidden from the consumer and the degradation only becomes measurable after the curve has flattened out.
     
  20. Salamander_King

    Salamander_King Senior Member

    Joined:
    Nov 8, 2015
    10,958
    8,836
    0
    Location:
    New England
    Vehicle:
    Other Hybrid
    Model:
    N/A
    I understand what you are saying, but to be honest, I do not have enough knowledge about the lithium battery chemistry and physics to understand how the "capacity" of the battery can be degraded without change in voltage. At least for the 12v lead-acid battery, the voltage measurements and overall capacity (State of Charge SoC) seems to be direct relation, at least that is what I have learned from reading several 12v battery maintenance threads. If the lithium battery is somehow different, I don't have a clear grasp of what constitute the degradation and how it happens.