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Downhill at "Set" speed not working

Discussion in 'Clarity' started by jdonalds, Oct 6, 2020.

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  1. Oct 8, 2020 #21
    ClarityBill

    ClarityBill Active Member

    I am also wondering if the brake lights come on for cars that do not have sufficient stopping power on ACC.

    Is this something that might have been changed on 2018 cars during an update?
     

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  2. Oct 8, 2020 #22
    jdonalds

    jdonalds Well-Known Member

    Redding, CA
    January 2020
     
  3. Oct 8, 2020 #23
    DucRider

    DucRider Well-Known Member

    My 2018 Clarity Electric does not use regen to control speed using either form of cruise control. I like it this way. I can engage regen with the paddle (and get the warning beep that freaks out passengers) if I want to slow, but often I will just carry the speed.
    Same thing if I reduce the set speed of cruise. It will coast with no regen down to the new set speed.
     
  4. Oct 8, 2020 #24
    ClarityBill

    ClarityBill Active Member

    Any way to know if your brake lights come on during the slowdown? I assume they do not, and your car is different than mine...
     
  5. Oct 8, 2020 #25
    insightman

    insightman Well-Known Member Subscriber

    Ann Arbor
    It wouldn't be surprising to find that an OBDII scanner can report brake-light illumination. The Honda e shows an image of the car on the dash and the brake lights in the image come on with the car's brake lights.

    I was so curious about when regen braking lit up the brake lights of our non-Clarity BEV that I installed an LED that I can monitor in my rear-view mirror. The Clarity didn't lend itself to such an easy mod, so its non-pedal brake-light illumination remains a mystery to me.
     

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  6. Oct 9, 2020 #26
    DucRider

    DucRider Well-Known Member

    AFAIK, the only time the brake lights are on without the brake pedal in use is during "Brake Hold". I don't think regen ever triggers them.
     
  7. Oct 9, 2020 #27
    ClarityBill

    ClarityBill Active Member

    I would agree with this opinion. Regen does not turn on brake lights, only friction brakes turn on brake lights. If that is true, my ACC must be using the friction brakes.

    My ACC will definitely turn on my brake lights. I can see street signs illuminating red in my rear view mirror, when I am descending hills in ACC. The illumination goes out when I turn off ACC. (2018 Clarity Base - Build 1/18)

    In ACC I get deceleration that is much stronger than I get with paddle regeneration: Very obvious when I engage with a setpoint significantly lower than speed.
     
  8. Oct 12, 2020 #28
    jdonalds

    jdonalds Well-Known Member

    Redding, CA
    I took the Clarity to the local Honda Dealer today to see about getting the ACC downhill issue fixed. When checking in for my appointment with the service technician I stated the problem as, "Everything with the car is fine except when using ACC and going downhill, when not following another car, the Clarity will allow the speed to increase well past the ACC set speed. He immediately responded calling it "freewheeling" and added he's heard of this issue often lately. I asked if it was just Clarity or other models to which he responded other models. I found this both encouraging and discouraging. Encouraging in that other owners think that the ACC is not working properly. Discouraging in that it is possible that Honda removed the feature intentionally.

    The case was turned over to the mechanic/technician who took it for a test drive returning with the comment that he could not reproduce the problem. He had also checked the Honda internal support website and didn't find other instances of this issue. He said he had not even heard of this issue. I told him I could reproduce the problem so took him for a drive on the hill that my wife and I transit 2 to 4 times each day. There the mechanic/technician witnessed our car gaining speed from the set of 41 mph to about 52 mph at the bottom of the hill. We tried it both in Econ mode and HV mode.

    The Honda dealer is going to check with their technical support and get back to me in a day or two.
     
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  9. Oct 12, 2020 #29
    JCA

    JCA Active Member

    That's good that they were willing to go with you and witness it; hopefully it will result in an answer.

    I took a fun drive this weekend from sea level to an 8000 foot elevation pass and back (CA-88), and on the way down used ACC some to see how it works in my car (2019 built in 12/2018). Mine does indeed seem to hold speed going downhill for short periods at least; I tested:
    • Setting a speed then using “-” to lower it -- the car pretty aggressively braked down to that speed
    • Setting a speed on a hill steep enough for the car to accelerate on its own -- it did seem to hold at that speed while if I canceled it the car slowly sped up.
    I was not able to try:
    • A hill steep enough or long enough that without using ACC manual paddle regen wouldn’t be enough to hold speed down and would require friction braking (I remember last year descending from Sequioa NP to Three Rivers after a few miles the regen would only go halfway into the first section).

    I still wonder if there's an intentional limit to how much long term braking ACC is allowed to do in no-car-ahead situations in a non-regen vehicle to avoid hidden brake fade, but it does appear to do some at least. Will definitely be interested to see what they find out, especially since I'm considering trading for a 2020 myself.
     

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  10. Oct 12, 2020 #30
    jdonalds

    jdonalds Well-Known Member

    Redding, CA
    My wife likes to hike in the Lassen Peak area with a friend. They usually drive up to about the 8,000 foot level. On the way up she uses HV mode which leaves the battery pretty low by the time she reaches the top. It's about 50 miles from home where we live at 750 foot elevation.

    On the return trip it is nearly 50 miles of downhill with some areas where the car is climbing. She put our 2017 into ACC and set a speed of 50 mph. The car would take care of the speed all the way down no problem. By the time she reaches the bottom the battery has regained most of it's charge. I've driven that road many times myself with the same result. I think the car is quite capable of applying sufficient regen and/or friction braking for that length of time.
     
  11. Oct 13, 2020 #31
    jdonalds

    jdonalds Well-Known Member

    Redding, CA
    The Honda dealer called me back today. She said the technician had contacted the internal Honda support line. He described his ride with me as I drove him down the hill near our house and the Clarity ACC did not control the downhill speed. Hondas response was that is normal behavior and there's nothing wrong with the car.

    I doubt if I'm going to end up with a fix but my next move is to somehow contact Honda to let them know my details about this issue. It seems clear to me that the 2018 Clarity PHEV cars do control downhill speed while somewhere along the line that was changed and the newer builds do not.

    This may be a non issue to some but my wife and I know what the old car did and it eased our driving process quite a bit.

    Perhaps I should have bought a Model 3. Had I known about this issue I might have.
     
    Peter CC likes this.
  12. Oct 26, 2020 #32
    JCA

    JCA Active Member

    On Friday I bought a 2020 to replace the 2019, and yesterday afternoon we took a 280 mile roadtrip to the mountains for some Sierra leaf peeping, which included some of the route I tried the 2019's ACC on a couple weeks ago.

    My 2020 definitely behaves differently -- it does not actively decelerate/brake to the set speed, either when reducing the setpoint with the "-" button or when the hill is steep enough that the car accelerates above the setpoint. The 2019 actively decelerated in both cases. The first case is testable/noticeable on flat ground -- going 70, rapidly press "-" to say 55 and the 2019 quickly slowed; the 2020 stays at 70 and gradually coasts down.

    And yes, using the paddle for regen cancels ACC, and hitting "set" while higher paddle regen is already set cancels that regen -- in fact, it sometimes felt like hitting "set" on a hill released even the normal small amount of regen braking that occurs, but that was harder to reproduce.

    It doesn't bother me too much; I don't use cruise control that often especially on mountain roads as it makes me feel less in control (I prefer to anticipate and slow a bit into curves and accelerate a bit when I can see it's straight for a while). But I can certainly see why it would be annoying and less useful for the many driving conditions and drivers. Mine was built in 6/2020 in case we find out they changed it mid-year, but it really does seem like an intentional change due to a safety or some other concern.
     
  13. Nov 8, 2020 #33
    Clarity_Newbie

    Clarity_Newbie Active Member

    Thought a video of the clarity speed controlled via ACC would help clarify.

    2018 Clarity Touring

    Interstate 6% downhill grade with speed set to 56 and two bars. 30 sec video to demonstrate consistency.

    https://photos.app.goo.gl/RpNPgZVHJSzVEa6d8

    The Clarity I drive has always performed this way.

    Hope this helps
     
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