HV and HV charge - TPMS quirk.

Discussion in 'Clarity' started by Tek_Freek, Oct 4, 2022.

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  1. We've been on the road since Friday and have found that when we use HV charge to bring the SOC to a higher level that when it reaches what looks like about 55% it automatically goes into HV mode.

    And the TPMS warning will show if you change altitude a lot like we have been.
     
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  3. Dan Albrich

    Dan Albrich Well-Known Member

    yes, the TPMS stuff (altitude) has gotten me many times. Kinda hate that because I don't feel this TPMS stuff should be ignored. It feels like my car is crying wolf.
     
  4. Robert_Alabama

    Robert_Alabama Well-Known Member

    I'm probably in the minority here, but I like that there isn't a real TPMS on this car. It makes it much easier to change out wheels (I keep 2 extra and just keep new tires on them - then change out tires and wheels whenever a pair is worn enough - makes it much more convenient than leaving the car at the shop or waiting there forever for it - just drop the wheels with old tires and pick them up when replaced). I use the aftermarket TPMS valve cap system and it hasn't failed me yet.
     
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  5. megreyhair

    megreyhair Active Member

    the TPMS is a joke. it only works if you have a flat in 1 of your tires. I eyes work better then the TPMS. I looked at my tires yesterday when I got out from supermarket and looked flat. I checked and all 4 tires were like 32 instead of 36. TMPS never lighted up.

    My pilot has actual PSI reading from each tires display in the dashboard. It even signal when I fill inflat the tires to let me know when I reached the suggested pressure.
     
  6. David Towle

    David Towle Well-Known Member

    I don't understand why TPMS warning should come up with an altitude change. Altitude should change the pressure of all 4 tires together, not individual ones, so that is something the TPMS should not be able to flag. The TPMS looks for different rotational times of the tires and warns when one is different I thought.
     
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  8. MrFixit

    MrFixit Well-Known Member

    I have a question about normal HV mode behavior:

    When in HV mode, the vehicle attempts to maintain a constant charge (EV Range) 'set-point'. When difficult conditions exist (sustained uphills) the EV range sags below this 'setpoint'. The Angry Bees may occur during this time as the vehicle struggles to produce enough energy. When this heavy load condition subsides, then usually the desired set-point returns over time (although some have reported observing a constant slow decline when in HV).

    My question relates to the opposite circumstance. Suppose you have a very steep sustained downhill and are operating in HV mode. Typically, I would have the ACC engaged (which conveniently maintains your speed even while going downhill). It does this using regeneration, BUT - I have never seen the EV range go higher than the HV set-point. Does this mean that operating in HV mode during sustained downhills is wasting energy and presumably dumping it into the engine (or worse - friction brakes)?

    I know that many report false indications of extremely high EV range numbers by capturing energy while going downhill, but does this only work if you are operating in EV mode? If you are on a long trip in Hybrid mode, but don't want to dump energy, then it seems like you have to manually do a dance engaging and disengaging HV mode every time you reach what you feel might be a sustained downhill?
     
    Last edited: Oct 7, 2022
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  9. Groves Cooke

    Groves Cooke Active Member

    "I have never seen the EV range go higher than the HV set-point."

    My observation also. 2018 with 52,000 miles
     
  10. ralfalfa

    ralfalfa Member

    I third the “EV never goes higher than the set-point”; and I’ve tried lots of times (like, hundreds). I have a fairly long and steep downhill as part of my homeward commute, battery is usually at 1/4 capacity and would love to recover a couple of miles of range. Which I can definitely do in EV mode, but not in HV mode. I have seen it tick up one tenth of a mile a few times but I think it’s the system struggling to round a number for display or something rather than any actual recovery of energy. And I don’t recall seeing any difference whether braking or not.
    So the obvious question is, what’s going on? Is regen off? Even if braking? Or is there energy recovery just not being reported?

    Oh, and 2018 with 38,000 miles.
     
  11. MrFixit

    MrFixit Well-Known Member

    It almost seem like the scenario where you do something demanding regen when the battery is full. The vehicle does engage regen, but since there is nowhere for the energy to go, it starts the engine (people hate this), and 'dumps' the excess energy into the idling ICE (converting it to heat).

    In this case however, there IS room in the battery. Often lots of room... But, in spite of this, it dumps energy into the ICE. The software seems to interpret the HV setpoint as an absolute cap, treating it like the battery is 'full' when it is not. Regen is clearly happening because the vehicle speed is not 'running away', but it is wasteful regen that is contrary to the basic principal of a super-efficient vehicle.

    Could this be an artifact of software re-used from a more conventional hybrid drive train where there is a MUCH smaller HV battery, that is constantly being cycled between 'full' and 'empty'?
     
    Last edited: Oct 7, 2022
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  13. I'm going to be contrary. My experience on our trip was seeing energy being added to the battery while going down hill with HV activated. It also showed the engine not running. I saw this a number of times. We had the graphic displayed showing the path of energy while traveling.
     
  14. MrFixit

    MrFixit Well-Known Member

    Yes, absolutely it adds energy to the battery when going downhill in HV mode, BUT only if the charge is below the setpoint. My claim / experience is that once it reaches the setpoint, then it no longer seems to add any energy. Does your experience refute this specific scenario?
     
  15. I honestly can't say. Knowing the set point on that iffy display is impossible.
     
  16. The real question is whether it's a display quirk--we all know that the guess-o-meter (GOM) is not very accurate. I think that many of the complaints of "HV charge doesn't actually hold" is people noticing their guess-to-mated range going down while using HV (when HV is likely [trying to ] keep the system-of-charge (SOC) the same [and sometimes struggling], but letting the GOM reflect the current driving situation for that SOC).

    My conjecture (probably wrong):
    • The engineers let the GOM go down in HV mode when the driving conditions get tougher (e.g., when climbing) because to allowing the GOM to overestimate range would lead to people running out of range, but
    • The engineers may have coded the system to have the GOM underestimate range when driving gets easier, so the GOM does not go significantly above the range that existed when you hit the HV button, because allowing it to exceed this range would confuse people. If you're actually banking power (e.g., going downhill) the actual SOC may be going up which is not being reflected on the GOM
    Seems we could test this conjecture with an appropriate ODBC reader...(or perhaps with a restart after the cycle and reread the GOM)
     
  17. MrFixit

    MrFixit Well-Known Member

    Although it is common to complain about the GOM, the reality is that neither the GOM (or the engineers who programmed it) can be clairvoyant. I think that much of the uncertainty (and driver's frustration) stems from the fact that the vehicle does not know what lies ahead and all that it can reasonably do is look back at some recent history and make an assumption that this will be representative of what lies ahead. There are times when there is a tremendous difference between the recent past and present and future operation in which case the GOM can seem to be wildly off. I feel that you are giving the engineers too much credit by postulating they were somehow 'fudging' the GOM in order to better meet what a driver might 'expect' to see. To me, they simply did the best they could to estimate range with good knowledge of the recent past an no knowledge of the future !

    Yes, some kind of experiment may be useful. Things are pretty flat here so I have little opportunity to experiment / experience the kind of sustained up's and down's that would facilitate this kind of test. I'll think about what kind of OBD2 instrumentation would make sense for this kind of test.
     
  18. My experience over the 2400+ mile trip was that HV Charge stopped at the same level every time and automatically switched to HV. The HV never added or lost bars while driving. Leaving the car running while gassing up maintained the same level. We drove through some pretty mountainous areas with a lot of up and down.
     
  19. coutinpe

    coutinpe Active Member

    In my particular case, when I get to the top of the hill and there is like a 10 mile or more downslope (I-15 from LA to Vegas), I turn off HV and ACC, just letting the car go down on EV mode and regulating speed with the regeneration pads, avoiding hitting the brakes as much as possible. The "EV range" (GOM) would go incredibly high (almost to the 80-90s) and I won't spend a drop of gas. This wouldn't work if I leave the ACC on, it would keep the engine on for some arcane reason. Next time I will use the CarScanner ODBII app to monitor what happens with the different parameters.
     
  20. MrFixit

    MrFixit Well-Known Member

    We don't have anything like your nice 10 mile down-slope here to play with, but I don't experience the engine running in EV mode going downhill with the ACC on. When you are controlling your speed with the paddles, but occasionally need to use the brake, it would be interesting to know if that is adding additional productive regeneration or does it actually need to use the friction brakes? Your observation that you need to turn off HV and ACC to capture the long downhill energy is consistent with my initial inquiry. I am not sure why Honda would no allow the EV range to exceed the setpoint in HV mode. It would be nice to just let the ACC maintain speed without having to putz around with the paddles / brake, while the vehicle automatically captures the excess energy. If the energy occasionally exceeds what it can use, then maybe it has to brake or run the engine a little, but it seems to not even bother once the EV range reaches the setpoint while in HV mode.
     
  21. ClarityBill

    ClarityBill Active Member

    Does the power meter go into charging mode on the long downhill?

    When I am going downhill in EV mode, I have seen the GOM increase, because it is using the immediate experience of easy miles to forecast longer miles on the remaining charge. I have an OBDII reader continuously on my car, and I see the GOM increasing, without an increase in battery SOC.

    If you are going downhill in HV mode, the GOM will stay at because it is not comparing battery SOC to miles driven.
     
  22. MrFixit

    MrFixit Well-Known Member

    Well,
    I am almost certain that the power meter was indicating charge, but I was focused on the GOM when assessing whether the energy was being lost. I suppose it is possible that the SOC was increasing and the GOM was not reflecting this. But - the GOM does go both up and down throughout all other aspects of HV operation ie: when going up a steep grade, the EV range drops, and then after leveling off (or going down) the EV range increases until it gets back to the setpoint, then it stops increasing. It just seems like there is a missing piece here. I probably won't encounter any sufficiently long downgrades for a while to have another look at this...
     
  23. I agree, been back and forth from 1,000’ to 5,000+ feet numerous times and never had the low tire pressure warning. Like David says, as long as the altitude or temperature or both affect all 4 tires equally, there’s no reason for the system to detect one wheel rotating at a different speed than the others, which is what triggers the alert.
     
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