HV Charge MPG experiment and results

Discussion in 'Clarity' started by Danks, Dec 2, 2019.

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  1. Danks

    Danks Active Member

    I think that driving certain stretches with certain climate control settings could get something on the order of 0.6 EV miles per mile driven. As I was driving I checked the EV miles gained between mile markers on I-96. During that 1 mile stretch I got between 0.6 and 0.7. As I watched the next mile it was clear I was not getting the same for that mile. I don't know what the difference is. After seeing the 0.6 for that mile I was surprised when I calculated it using the actual EV miles gained vs miles driven that it was as low as 0.3. It is not a steady 0.3 EV mile for every mile. I need to test it at MIS where every 1.5 miles is exactly the same.

    I should make it clear that, if under certain road conditions and climate settings one can get better HV Charge mpg, they would also get better HV mpg and that HV Charge will always be less than HV.
    Last edited: Dec 4, 2019
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  3. Mike95465

    Mike95465 Member

    Ok. I set myself up to do another experiment starting tomorrow for the next two days. I did a quick run on my way home from work today. Topping off shortly after leaving, using HV charge to gain enough EV miles to top off again near home and glide into my garage with 0.0 EV range.

    Quick test
    Miles driven: 31.8
    Infotainment calculated MPG: 47.9
    Gallons topped off: 0.638
    Hand Calculated MPG: 49.8

    Tomorrow, I will do a full commute. Using HV charge to max
    Use EV to depletion
    Use HV charge until enough to get me to gas station to top off and glide into garage with 0.0 EV miles.

    Friday, I will another full commute.
    Use HV mode the entire commute, still with 0.0 EV miles
    Top off when I get home

    I will document the following:
    Garage temp in morning
    Outside temp during morning drive
    Outside temp during afternoon drive
    Miles to HV charge max
    Miles generated during HV charge
    Total miles during each commute
    Gallons required to top off each commute
    Infotainment calculated MPG for each commute
    Hand calculated MPG for each commute

    Notes for the experiment:
    Blizzak WS80 on 17” rims are equipped
    Normal full EV range that I’m getting right now is 46 miles
    Seat heaters on max
    HVAC off
    Tire pressure just checked and set to 39 psi cold
    HondaLink indicates 11% when at 0.0 EV range
    Same gas station and same pump will be used filling at the lowest lock position on the handle

    Any comments?

    Sent from my iPhone using Tapatalk
    Last edited: Dec 4, 2019
  4. MrFixit

    MrFixit Well-Known Member

    Nice !!!
    I especially like the "gliding into the garage with 0.0 EV".
    If you have a couple tenths left, you can always sit in the car with the heater on to burn up a few more watt-hours !!

    Seriously though, I appreciate your quest for knowledge.

    Somebody mentioned a possible inconsistency with the gas pump cut-off.
    I would think that your same station, same pump plan would yield a minimal uncertainty.
  5. KentuckyKen

    KentuckyKen Well-Known Member

    Just be sure when doing the same pump fill up that you insert the nozzle the same depth so the shut off is as similar as possible. You’ve got a respectable scientific method going. I’m optimistic about the validity of your results. Sound like the best you can do outside of a laboratory.
  6. Something just occurred to me...

    A lithium ion battery has a finite number of charge-discharge cycles.

    Which would better:

    1) One long, fairly continuous discharge cycle, followed by tiny charge/discharge cycles once the car hits “0” “at the bottom”, or...

    2) More shorter cycles, let’s say repeatedly going to “0”, then charging up to 58% (or whatever) and repeating as necessary.

    I honestly don’t know if it makes any appreciable difference at all in battery longevity.

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  8. I have seen LiFePo charts that show:
    3,000 charge cycles down to 100% DOD, 4,500 cycles down to 80% DOD and
    10,000 cycles down to 60% DoD.
    After which, the batteries retain 80% of their original capacity.

    This is under laboratory conditions with controlled rates for both charge and discharge.
  9. Mike95465

    Mike95465 Member

    Here are the results of the experiment I performed.

    Commute in HV Charge
    Garage temp in morning 45
    Outside temp during morning drive 35
    Outside temp during afternoon drive 42
    Miles to initial HV charge max 35.1
    Miles generated during initial HV charge 27.2
    Total miles during commute 76.7
    Gallons required to top off commute 1.720
    Infotainment calculated MPG for commute 51.7
    Hand calculated MPG for commute 44.59

    Commute in HV mode
    Garage temp in morning 48
    Outside temp during morning drive 38
    Outside temp during afternoon drive 39
    Total miles during commute 79.0
    Gallons required to top off commute 1.858
    Infotainment calculated MPG for commute 47.8
    Hand calculated MPG for commute 42.51

    Notes from this experiment:
    Keeping energy flowing into the battery in either mode occurs when kept below 1.5 rungs of energy meter
    I am still not sold on the accuracy of pump stop valve. I verified that I inserted the nozzle as far as I could during each top off.
    I do a few very short low speed drives while at work throughout the day, HV charge mode had a benefit as I used EV during these short drives and HV had to kick on the engine.
    No angry bees throughout experiment, however, HV charge was more pleasant during commute compared to HV since the engine was not kicking on and off.
    I am sure that I can eek out a few more MPG in either mode by driving even more conservatively or even just driving the speed limit.

    I will try this again in the summer with my regular stock tires and wheels too see if there is a difference. I will also try again if I happen to forget to plug my car in like I did when this experiment started.

    Sent from my iPhone using Tapatalk
    Robert_Alabama likes this.
  10. MrFixit

    MrFixit Well-Known Member


    This experiment seems to have yielded the opposite of the first one.
    In the first experiment, HV Charge was around 4% worse than HV.

    This time, HV Charge was better (to the tune of 5-7%) than HV.

    It seems like maybe there are some factors beyond your control that have a non-trivial impact with a limited test like this.
    Things like how you happen to hit traffic lights, or varying speed when other traffic is affecting you, etc.

    Both methods (hand and infotainment) showed the same trend (to a slightly different degree).

    Note that the Infotainment was reading a higher MPG in both cases (as reported by others) - It read high by 15% in HV Charge, and 12% in HV.

    It is probably safe to say (at least with the driving conditions of your commute) that there doesn't seem to be a noticeable penalty when using HV Charge.

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