Any difference between HV and HVCharge modes on energy screen

Discussion in 'Clarity' started by Chooch, Dec 9, 2018.

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  1. Chooch

    Chooch Member

    So after watching this video about modes, I don’t think this is what my Clarity actually does. Specifically with regard to HV and HVCharge modes: as I see it the video shows that in HV mode, there will be a blue power flow line from both the ICE and the battery, showing that they are working in conjunction to power the wheels but no green line. Whereas in HV Charge mode there will be a blue line from ICE to power the wheels but also a green energy flow to the battery showing that it is also charging the battery. However in my car sometimes there is that green line charging battery in regular HV, not only in HVCharge. And it does not only occur when I am down to 2 or 3 bars in regular HV. I can have any amount of battery left and if I put it in regular HV, it is going to have that green line happening off and on for most of the time. It’s almost like there is no difference between HV and HVCharge in terms of the driving experience. I am wondering if anyone else has noticed what their power screens show in each mode or could take a look and share. I understand that when I am coasting or regenning, I should see the green line but that makes sense to me, the deliberate charging of battery (at least thtat is what I think the green line means) when driving on flat road in regular HV doesn’t though. I am wondering if this is normal or if I need to take it in to the dealer. Thanks.
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  3. Viking79

    Viking79 Well-Known Member

    HV or HV charge will be indicated on left of instrument cluster and HV charge will actually bring the car back up to 60% charge or so if there is extra power. It takes it a bit to start charging (like it warms the engine up first if I recall). HV holds it about where it was set.

    In normal HV the car charges if it needs to, which is why you see the green. At highway speeds it tries to use engine to power wheels with the balance of power coming from the battery or going to the battery, but can also use its CVT mode with the engine decoupled. In general it does whatever is most efficient at the time.

    Basic level is HV will hold the charge level and HV charge will try to take it back to 60% or so at which point they would act the same.
  4. Richard_arch74

    Richard_arch74 Active Member

    @Chooch, let me share this anecdote. I was driving on the highway (relatively flat) going approximately 70mph in HV mode (and not in Econ, I think). I notice that my EV range was 20 miles. As I watched the dashboard (light traffic) noticing the flow of energy to and from the ICE and battery the EV range dropped to 19 miles. As soon as the range dropped to 19 the green flow from the ICE to the battery brought the range back to 20. The EV range kept floating between 19 and 20 for many miles. When in HV mode the engine wants to recharge your battery intermittently depending on the Honda engineer's algorithm that we will never see or understand.

    Sent from my SM-G955U using Inside EVs mobile app
  5. leop

    leop Active Member

    The question is if the gear icon (engine directly coupled to the drive train) stayed on when the battery was being charged? Or, did the gear icon go off when the engine was charging the battery? In more technical terms, if the engine decouples, the system is in the series mode (engine producing electricity which runs the traction motor and/or charges the battery. If the engine stay couples, the system is in the parallel mode where the engine drives the wheels and can also charge the battery. It appears that after the SB Campaign update, the system may not stay in the parallel (coupled mode) when charging the battery.

  6. Presumably it's trying to maintain ~20 miles of EV range, not for actual EV use but as a supplement should you get to hilly terrain. I'd be interested in seeing if it's always ~20 miles--they could (for example) have fewer in Kansas and more in Colorado...
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  8. Richard_arch74

    Richard_arch74 Active Member

    There isn't anything magical about the 20 miles of EV range. If I was at 30 miles of EV range, in HV mode, it would keep it at ~30. When I took a trip to Tennessee (long/steep hills) a few months ago I was having a harder time keeping my EV range.
    As far as Leop's post: I can't say I have noticed the gear icon. I guess I will have to be more observant.

    Sent from my SM-G955U using Inside EVs mobile app
  9. leop

    leop Active Member

    The gear icon only shows up if you have the energy flow display showing on the driver's display or the larger center display. LeoP
  10. Eddgie

    Eddgie Active Member

    The most useful info when in HV mode is shown on the white arc of the power display. At speeds above about 47 mph, this white arc is what tells you when the ICE will turn on, or how far you can press the accelerator before the ICE comes on if you are above 47 mph and the electric motor is driving the car.


    In HV mode, the ICE does not always provide the motive energy. At speeds below 47 mph, the electric motor is the exclusive source of propulsive energy. Above 47 mph, the ICE can provide much of the propulsion but it does not provide the propulsion all of the time and the electric motor can either assist, or completely propel the car. At low speeds in HV mode, the ICE cycles on and off as necessary to keep the battery State of Charge (SOC) to be about what it was when you put the car in HV mode but the ICE never directly drives the car.

    If you are driving down the road at say 60 mph, this is what you will see if you have the energy display on. You will see the gear icon come on and go off as the car changes between the ICE and electric motor drive, and if you have the fuel consumption panel on, you will see the MPG show about 38 to 44 mpg when the gear is on, and 199.9 when the gear goes out (ICE shuts off).

    If you are watching when the ICE shuts off, you will see the white arc above the power draw indicator with a space of dashed white lines between the power indicator and the white arc. Almost immediately, the gap between the power indicator and the white arc will start to close, and when the what arc gets to the power indicator, the ICE will start and start driving the car and charging the battery, and instantaneous MPG will drop down to about 38, and the motor will both drive the car and put a bit of electricity back into the battery.

    And as long as you are just crusing along, you will see this condition repeat itself over and over and over.. Electric only, then as the white arc hits the power delivery line, ICE starts, gear icon shows up, battery starts to charge and when the battery gets a bit above the charge it had when you went into HV mode, it will once again declutch the ICE, stop it, and run off of battery until the solid white arc gets back to the power indicator.

    Now, if you need a bit more power(hill) while the ICE is driving the wheels you will see that power will now flow out of the battery even though the ICE is running. The electric motor is now assisting ICE but because the ICE is geared to the wheels, it can't do much to charge the battery in this condition (because the rate of charge is proportional to the RPM of the ICE, and if the ICE is driving the wheels, then it can't also offset the battery drain). If you get to the point where the ICE can't provide enough power, the ICE will disconnect from driving the car, and the electric motor now gives 100% of the driving force to the wheels. If the hill is very steep and the electric motor needs full power, the ICE will start and run as a generator to provide it, and if enough power is requested, the ICE will go to it's highest charge RPM (Angry Bees).

    This is a tiny ICE and on its own, really incapable of doing anything but powering the car an highway speeds on flat roads. Any hills or any acelleration will require electric assist, and when the demand gets high enough, the ICE disconnets from the wheels and becomes only a generator and will run at the speed required to provide the current needed for the power demanded. If that is a lot of power, you get the angry bees (ICE running at high RPM).

    Sorry if my explanation is not clear, but it is really simple in that in HV, the car makes the necessary decisions to keep the state of charge at about the level it was when you entered HV mode and this means that it will use the SOC and power demand to decide whether the car should be running full electric, full ICE (with recharge generation from ICE) ICE with electric assist, or when very high torque is needed, full electric with ICE running as a generator at the RPM necessary to provide the necessary amperage to the electric motor.
    228ra likes this.
  11. Eddgie

    Eddgie Active Member

    And of course the energy display is not really needed. You can tell pretty much everything from the power display and instantaneous MPG readout. I never use the Energy display (or whatever it is called). Seems kind of useless to me because again, you can tell what the car is doing and is going to do using the info in the picture above.
    Last edited: Dec 9, 2018
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  13. KentuckyKen

    KentuckyKen Well-Known Member

    I consider my Clarity to be one of the ones blessed with “normal” behavior since it runs perfectly with no loss of power or angry bees ever.

    I can state unequivocally that in HV, I have seen every possible combination of power flows. And that includes gear (Engine Drive) both with and without charging the battery, and even EV (battery only) for very short times. My Clarity in HV, provides plenty of power with no angry bees and keeps my battery at its starting SOC within one bar. It cycles the ICE on and off, using the battery for extra power when needed and charging the battery when it can, all while I assume the PCM is finding the prescribed mix of drivability and efficiency. On a recent trip I got 49 MPG and after accounting for the small use of battery power it was 48. So I am not doing any of the updates (except for the HV range) since I like her just as she is.
    I have yet to press the HV Charge button and only see it useful if I were find myself faced with a long mountain climb coming up and I’d let the battery deplete too much to have enough charge for the climb.
    Robert_Alabama likes this.
  14. David Towle

    David Towle Well-Known Member

    Great description but I think you left out modes where I put the ****** in above. If you are going slightly more uphill the ICE will propel the car and send a little charge to the battery constantly, no off and on. A little more uphill and the motor will just gear propel the car with no flow in or out of the battery. Then onto the next mode.
  15. jdonalds

    jdonalds Well-Known Member

    Good description. In addition to the ICE being small it is also an Atkinson Cycle design which is very efficient but not strong for accelerating. That's why it just fills the need for constant speed low energy.
  16. insightman

    insightman Well-Known Member Subscriber

    @KentuckyKen's right. This chart from the Honda engineers' SAE paper (which I modified to include charging under Engine Drive mode) illustrates the operation of the Clarity PHEV in HV Mode. Note that the "Mode" line at the bottom of the chart refers to the Clarity PHEV's 3 basic drive modes, EV Drive mode (battery-only powering the traction motor powering the wheels), Hybrid Drive mode (battery+engine-driven generator powering the traction motor powering the wheels), and Engine Drive mode (engine powering the wheels together with the battery powering the traction motor also powering the wheels). Note that the starter motor/generator is disabled during Engine Drive mode.
  17. leop

    leop Active Member

    Insightman correctly quotes the 2014 Honda paper on the i-MMD system that the engine mounted generator (starter motor/generator) is disabled during the engine direct drive mode (engine directly coupled to the drive train). In the current version of the Clarity's i-MMD system, I do not think that the engine mounted generator (the starter motor/ generator) is necessarily disabled in the engine direct drive mode. I was under the understanding that the gasoline engine could charge the battery if extra engine power was available while still directly driving the wheels. My understanding is supported as this mode of operation is explicitly shown on page 132 of the Clarity Owner's manual. This mode of operation, a parallel mode, is also used in the current version of the Prius as well as some other PHEV's. I recall our Clarity, built in October 2017, showing this direct drive and charging mode before the October Campaign updates were applied. The engine mounted generator was not always disabled during the engine direct drive mode.

    I am not certain that this mode is currently available (after the updates) as I did not see this mode during four short drives (about 20 miles each) at freeway speed with HV mode enabled. It also appears that the engine direct drive mode, after the updates, is used less and the system more often goes into the series mode where the engine just drives the engine mounted generator when extra torque is needed at freeway speeds.

  18. insightman

    insightman Well-Known Member Subscriber

    Yes charging can occur in Engine Drive mode, but instead of the starter motor/generator, it's the traction motor charging the battery, as it does when performing regen braking. Only in Engine Drive mode are the engine and traction motor mechanically connected.
    KentuckyKen likes this.
  19. KentuckyKen

    KentuckyKen Well-Known Member

    @insightman is correct that published material from Honda says the generator doesn’t work when in engine drive mode (gear symbol illuminated). Also supported by a doc that @AnthonyW posted, I believe.
    However, in real life, I got the gear symbol AND green flow going into the battery symbol at the same time. I can’t explain that but offer it up as a valid observation. Also got the gear symbol on speeds as low as 48 mpg.
    Unexpected but true.
  20. KentuckyKen

    KentuckyKen Well-Known Member

    Thank you. I had forgotten that. I’ll take that as my Christmas present from you!
  21. leop

    leop Active Member

    Insightman is correct in saying it is the traction motor (switching between traction and generating modes) that does the charging in the Engine drive mode. I misspoke in this case as the starter motor/generator can stay disabled. Mea Culpa. But, as KentuckyKen said, a Clarity, at least before the updates, can charge the battery while in Engine Drive mode. I just have not yet seen this in our Clarity after the October updates. I will be on the look out when we next drive on the freeway in HV mode.

    KentuckyKen likes this.
  22. rodeknyt

    rodeknyt Active Member

    And, let me add to the confusion.

    Made a drive last Friday starting in EV (Econ) with a full charge. I live in the foothills, and being in a bit of a hurry I couldn't avoid triggering the ICE with normal braking. I drove down two miles to the freeway, got on and drove about 14 miles at 65-ish speed. After the point that the ICE usually shuts off in this circumstance, it continued (no "EV" coming back on the display). I switched the display to the power flow screen and saw that both the ICE and battery were sending power to the traction motor.

    During the drive, the EV range went down in an amount I would expect while driving in EV mode, but the HV range didn't go down at all. This continued until I was almost to the end of the drive when the car switched back to EV mode and the ICE shut off (as shown in the display). And I still had the same HV range showing as when I started the drive despite the ICE running the entire time. I've never seen this happen before...I'll usually lose a mile or two of HV range when the ICE comes on with the downhill drive with a full battery.

    Yes, I had the HV range software update.
  23. Atkinson

    Atkinson Active Member

    When you are in "engine drive" mode, the engine is running at fixed throttle regardless of where you have the accelerator pedal.
    Moving your foot on the pedal simply changes the amount and direction of electricity flow.
    Cruising at steady state and no blue or green lines (takes practice) and the engine drives the car with no power from the battery or to the battery.
    Push the accelerator harder and the engine continues at the same throttle, but the battery assists.
    Release the accelerator slightly from steady state and the engine continues as previously, but power to the wheels is reduced (slowing the car) by adjusting the charging rate to the battery.
    Less accelerator = more charge.
    This continues until the battery is charged to the top of the HV range it started at and then switches to EV mode until charge drops to the bottom of the HV battery bubble.
    More accelerator = less charge, no charge, then gradually increasing battery discharge.
    If enough battery level is consumed below the low end of HV range with aggressive driving, the clutch will unlock to allow the engine to go into varying levels of "angry bees" territory (over 3000 RPM) to charge the battery at high rate until the you are back in the HV range bubble.

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