Here we go again with the crazy GOM

Discussion in 'Clarity' started by coutinpe, May 8, 2020.

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  1. coutinpe

    coutinpe Active Member

    Yesterday I drove into the freeway and switched to HV/Sport. I noticed the HV range didn't change at all after driving 15 miles at 75 mph and then it decreased a couple of miles in the last few minutes, while the EV range decreased 5 miles. On the way back, I drove again in HV mode and the HV range fell accordingly until I left the freeway, switching back to ECON mode. However, in spite of the green EV letter displaying on the dashboard (meaning the ICE was off?), the HV range kept decreasing and fell 3 miles during the 4 miles I drove through the streets, falling together with the EV range. Any theories? Thanks.
     
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  3. If you started with a full fuel tank, it could easily take 10-15 miles of travel for the sensors to register the change and adjust the estimated range. That’s only about a quart of gas. I’ve noticed the same with the battery gauge, often going 5-6 miles after a full charge before it drops one bar. After that, it’s a bar every 2-3 miles depending on speed.

    Regarding your second observation, it could just be the computer is recalculating the fuel level and adjusting the estimate.

    As we know, it is just an estimate and isn’t always accurate. Same as fuel consumption provided by the trip computer. My experience is that it is optimistic by about 10% compared to actual miles driven and fuel added. It shows 40 when actual is 36.

    Those are my theories. If you don’t like them, I have others.
     
  4. craze1cars

    craze1cars Well-Known Member

    Didn’t drive far enough for everything to find its leveL. Normal. If you observe behavior after a good 50 mile or more highway run, without pushing any buttons or changing modes, you’ll see it all makes sense. But every time you shut the car off, or simply change modes it resets the system and it starts all over again so you’ll never see a straight up reading that makes sense.
     
  5. Maybe I’m misunderstanding your statement. My HV range remains unchanged for days and weeks of daily EV driving even after shutting the car off and turning it back on numerous times.

    If a full fuel tank shows 280 miles of HV range, it will remain at 280 until some fuel is burned, day after day. Use HV for 20 miles, range drops to 260. It will stay there for countless EV trips, until more fuel is burned.

    Switching from EV to HV resets the battery SOC level that the vehicle attempts to maintain. I have not experienced switching from EV to HV to EV resetting the HV range estimate other than based on the amount of fuel consumed while in HV. Nor have I experienced HV range resetting from simply turning the vehicle on and off.

    Can you elaborate on your statement?
     
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  6. coutinpe

    coutinpe Active Member

    What you point out has been my experience so far. It is the first time I see the HV range dropping with the ICE off in 15 months owning the car, which I found strange enough to post it in the forum to see if someone else has seen something similar.
     
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  8. coutinpe

    coutinpe Active Member

    I started with a full tank indeed. Your theories seem pretty rational so yes, I like them. Nevertheless, it is the first time I notice the HV range dropping with the ICE off. Probably I wasn't paying enough attention before.
     
  9. craze1cars

    craze1cars Well-Known Member

    I misread. Thought it was EV range dropping a few nuggets with engine on, not HV dropping with engine off. I have nothing to add as I don’t pay much attention to small estimated range fluctuations. I take them as estimates, not gospel. Sorry for confusion.
     
  10. KentuckyKen

    KentuckyKen Well-Known Member

    Ill throw out one possible explanation on how the HV estimated range can drop a few miles while driving in “EV”.

    As an aside, @insightman correctly reminds us, there is no pure “EV Mode” we can select. And to add to the confusion, Honda uses Drive Mode to describe Econ, Normal (which doesn’t even have a button and is just being in neither Econ nor Sport), and Sport which all can be used to modify the 3 propulsion or power sources of EV, HV and, HV Charge. And again, like the Normal Drive Mode, EV has no button and is actually achieved by being in neither HV nor HV Charge. I’m still a little confused by the way Honda chose to define and implement all this even after 2 years and @insightman ’s tutelage. Fortunately it all works fine since the car’s programming doesn’t care about how Honda mangled the manual on all this.

    I bring all that up to remind us that you can’t put the Clarity into a pure EV state that prevents the ICE from ever turning on even if you don’t go past the click/detent in Econ Drive Mode (or the pre-click/detent advanced point in Normal or Sport).
    Even when driving in what most call “EV mode”, the ICE can come in for various reasons such as heavy use of climate control, temperature extremes, extremely low high voltage battery SOC, and System Checks. While it’s not mentioned in the manual, there is also a well documented “Regen limited by a full battery so ICE comes on to somehow protect from over charging” scenario. And then throw in the fact that once the ICE comes on, it’s programmed to stay in until it reaches operating temperature. Also, the System Check can even cause the ICE to stop and restart on occasion.

    In your description, I would conjecture that a System Check may have occurred. I drive ~95% in EV, and have noticed that every month or two, my ICE will come on for for just a few minutes (2-4) for no apparent reason and when the battery is not fully charged so it can’t be the limited regen/ICE start scenario. I attribute these short and infrequent ICE runs to be System Checks which are keeping the ICE lubed and ready to instantly start whenever called upon. When this happens, I lose a couple of miles of HV range and since it’s only at idle or near idle rpms, it’s very easy to not even notice it until you see the HV range drop.

    I have observed the following when this happens and you can be on there lookout for these indicators next time.
    The EV indicator will not turn off even though the ICE is running. The small engine icon in the center screen Power Flow Monitor will indicate, but again it’s easy to miss since it’s small and just lights up a little more, and you have to have that display called up. The only real indicator I’ve found of a System Check is that the Power/Charge Gauge will turn completely white with no blue and stay that way until you restart the car even when the ICE has turned off and you’re back to driving solely on the battery.
    On two occasions, I’ve noticed my HV range drop a few miles when I’ve sworn the ICE had not come on. However the hour meter I installed on the engine had incremented for one of these and since it only reads down to tenths of an hour, it may have missed the other. That’s not to say that the HV range can’t change without an ICE start, as in the fuel probe reads the gas level a little differently. It just seems that for my car any reduction in HV range is always accompanied by an ICE start or a fuel addition in the case of a gain.

    Next time it happens, be on the lookout for the Power/Charge Gauge turning all white but you will have to notice it before you turn off the car. In any event it’s not something to worry about.
     
    Last edited: May 9, 2020
    Texas22Step, coutinpe and insightman like this.
  11. coutinpe

    coutinpe Active Member

    You're right, I think the only explanation is that the EV indicator kept on even tough the ICE was actually running. I would have been able to see that if I had the power gauge instead of the GOM range gauge. Once again, I wonder why they wouldn't fit both things together. I think there was space enough.
     
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  13. insightman

    insightman Well-Known Member Subscriber

    Honda is protecting you from becoming overloaded with TMI. Good old Honda, always thinking of you.
     
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  14. coutinpe

    coutinpe Active Member

    Resurrecting this old thread with a new development!
    Courtesy of Covid-19 or whatever it's name is, I have not needed to visit a gas pump since I don't remember when. The HV range has sit at 270 miles for at least 45 days since the last time I hit the freeway and I have detected no activity of the ICE on my short weekly drives in ECO mode to the grocery store or the nearby hiking trail. Then yesterday the HV range suddenly jumped up to 283 miles. I swear I have not put a single drop of gas into that tank. Has anyone noticed something like that?
     
  15. Kerbe

    Kerbe Well-Known Member

    It's probably elves - check the trunk to see if they also left you a pair of shoes.
     
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  16. coutinpe

    coutinpe Active Member

    I would prefer a mithril sword or chain mail but I'll take whatever they bring.
     
  17. Danks

    Danks Active Member

    Yes, and I have a theory as to why this happens. The hybrid battery contributes to HV driving and is included in the HV range estimate. So, if the EV range changes enough one way or the other, it will contribute to changing the HV range - even when the car hasn't been driven in HV.
     
  18. rodeknyt

    rodeknyt Active Member

    I don't think so. I've driven my car for months without the engine running and the HV range doesn't move.
     
  19. coutinpe

    coutinpe Active Member

    Which had been my case until now and I have had the car for 18 months and in COVID EV only for 3. That's why it called my attention when HV range jumped 13 miles.
     
  20. Danks

    Danks Active Member

    Sorry, I wasn't clear. What I am suggesting is that if the full EV range changes enough - say from 40 miles fully charged to 55 fully charged, then that might be enough to trigger a corresponding increase in HV range. It isn't how many months running in EV with no HV, it is a significant change in how many EV miles you get on a full charge. It makes sense to me that if your EV range increases by 20% then, since the hybrid battery contributes to HV range that it will some increase too.
     
  21. rodeknyt

    rodeknyt Active Member

    Since you live in an area that actually has four seasons, and really cold winters, you could be correct. I'm in SoCal and see only about an 8-10 mile variation throughout the year on estimated EV range on a full charge. And I suspect more of that variation is due to driving pattern (I live in foothills) than temperature.
     
  22. Danks

    Danks Active Member

    I noticed last winter when our EV range dropped from 55 to 35 that shortly afterwards our HV dropped - even though we had not driven any HV. Our driving pattern is boringly constant.
     
  23. When HV mode is engaged, the vehicle attempts to maintain the high voltage battery SOC at that moment in time. HV mode “utilizes” the energy stored in the battery. Given the appropriate opportunity, it will also replace nearly all of that energy. HV mode does not use up the energy in the battery to achieve the HV range estimate. Yes, the battery gauge will drop a couple of bars on a long trip and EV range may decline a few miles. My best guess is that Honda determined that it would be inefficient and pointless to operate the ICE until the battery was fully charged.

    Theoretically, under identical conditions, the vehicle would achieve the same HV range, on the same amount of fuel, with the battery at 50% or 100%.

    I can’t explain the increase of 13 miles of HV range without the addition of fuel, other than to say it may have been a sensor/computer recalibration.

    In my experience, the EV range, or battery SOC, has little to no impact on HV range. The possible exception would be a depleted battery which may cause the ICE to run more frequently, thereby reducing HV range.
     

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