Clarity Issues

Discussion in 'Clarity' started by jdonalds, Dec 22, 2017.

  1. Ray B

    Ray B Active Member Subscriber

    Really sorry to hear that, Dennis.

    Can I recommend you install an OBD II datalogger to record these events? I know it sucks to have to spend money on it, but at least it will give some data for Honda to look at the next time (hopefully there is no next time).

    Here is one I purchased for $22 on Amazoon ( and then the Torque Pro app was another $5 I think (Android only - not sure what Apple options exist). It logs my drives to my phone and then I can download data whenever I want to review any specific events or behavior.
  2. KentuckyKen

    KentuckyKen Well-Known Member

    @DennisH, that is absolutely not normal behavior and I would escalate this as far as I had to go to get Honda to own up to this problem. I can assure you my Clarity has never done this in the same scenario.
    I note that the car sat on the dealers lot for at least 7 months. The PDI says the battery may be damaged if not charged at least every 3 months. I’d be very suspicious that the dealer didn’t keep the battery charged and damaged it. I suggest you have them measure the Battery Capacity Signal to prove to you that your HV battery is OK. It’s nominally 55 Ahr when new.
    I hope you can get some traction on this and get it resolved so you will have a Clarity that functions like it should.
    Robert_Alabama likes this.
  3. JCA

    JCA Member

    I agree with insisting they check the battery. My understanding of the Clarity system is that because the engine can only be directly connected at one gear ratio, it requires a certain amount of battery power to be available at all times to provide some/most of the torque for starting and accelerating. The computer ensures there's always that amount in reserve, going to HV mode before the battery is fully depleted (there are other battery life reasons for that also). But a bad cell could make it appear like there's anough amp-hours left, but when it actually goes to use it, it drains too quickly leaving you with little to no motor power and an engine that can't really compensate.

    That's my theory from the sidelines -- disclaimer that I don't own a Clarity (yet!), but have had 2 Highlander Hybrids that probably work similarly (requiring electric motor for much of the torque). It does sound dangerous and I hope they resolve it -- tell them that there are potential customers who are watching to see how problems like this are handled before jumping in!
  4. Robert_Alabama

    Robert_Alabama Active Member

    I concur that I would push the dealer to figure this out.
    I wonder if somehow your Clarity is "overly depleting" the battery (or thinks it has) before it starts the ICE. I own a 2012 Chevrolet Volt. Chevrolet designed the Volt so that the surplus in the battery would shrink over time, allowing you to keep the same range even as the battery degraded. It now has 73k miles on it and I have found if I let the battery go to zero and start the ICE, it will sometimes rev like crazy, and limit propulsion so it is a struggle to get above 50 MPH, and throw a message on the dash. It will then recharge the battery a little and get over the fit, but it can be pretty unnerving if on an interstate highway when it happens. After two occurrence of this (once on the interstate), I have found the way around this is to use Mountain mode on long trips to hold the battery at 1/3 charge (I just put it in mountain mode on the trip when the battery is 2/3 depleted). This keeps the revving from happening and prevents the loss of power. When I get close to a charging destination, I drop it back into normal mode and use up the most of the last of the battery without dropping into the ICE. Chevrolet's fix for this (It has happened to several of the aging Volts, so they had to address it) is to reduce the usable amount of the battery (reduce range) to get surplus back at the bottom (think of that as our 2 bars on the Clarity). As to how this might apply to your Clarity, maybe the battery really is in too low of a state of charge when this behavior kicks in (either due to damage as KentuckyKen suggested), or for some reason the car just thinks this is the case (sensor/computer issue).
    KentuckyKen likes this.
  5. Eddgie

    Eddgie Active Member

    I can reproduce this failure at will. It happens to me when I open the trunk to get groceries. I keep the key in my right pocket. If I stand square to the direction of travel of the car, when I open the trunk, I get the error.

    If on the other hand, I turn so that my right side (key in right pocket) is away from the car, I do not get the error (well most of the time I don't get it if I turn this way).

    Clearly, in my case at least, the error is that the sensor for the trunk is reading the key in my pocket and thinks it is still in the car.

    Annoying. Once I learned about it though, I mostly stopped having the error by turning my left side to the car when I open the trunk, I mostly stopped having the error.

    If I just exit the car and walk away, I never get the error.
  6. Phunny

    Phunny Member

    This seems like a good theory. It sounds like the engine started revving to charge the battery and there was not enough power diverted to traction, possibly because the control system got wrong information

    I've felt the sensation of losing power for a moment on the highway, but it was short lived and similar to an automatic transmission hunting for a gear. If something is wrong, I could see the car not getting out of the loop.

    This issue seems rare enough that it could be a software bug that only gets triggered by a hardware issue. If it we're just a hardware issue, I think it would be easier to reproduce. And if just a software issue, it would be more widespread and it wouldn't strike some cars more often than others. It will be tough to find the software issue unless you get Honda USA motivated. So your best bet is to look for hardware issues.
  7. MNSteve

    MNSteve Well-Known Member Subscriber

    I do. But I can't figure out what I am doing to cause it.
  8. Casey Martin

    Casey Martin Member

    My car has done this a couple of times. Both times it was when I was in HV mode with an almost full battery. There is a bridge about 3 miles from my work. I was coasting down the back side of the bridge and rolled through the EZ Pass toll booth at about 40+ MPH. After exiting the toll booth I tried to accelerate and there was almost zero power. The ICE was screaming but the car barely accelerated. It was very odd especially since the battery was almost full. I am guessing but it seems to be an issue around 45-50mph. I believe that is when the "transmission" can "lock up" with the ICE. I don't know the exact technical terminology but that is what it feels like. It seems like when it is "locked up" in HV mode it can't use power from the battery. Then when it "unlocks" it goes back to having full power. This problem should be correctable with a software update once Honda figures out what exactly is causing this to happen.
  9. Ray B

    Ray B Active Member Subscriber

    I wonder if the car is confused about whether the clutch is engaged. Meaning there was a bug in the system where it was asking for the clutch and then the system thought the clutch was engaged when it actually wasn't.
    AlanSqB likes this.
  10. AlanSqB

    AlanSqB Active Member

    Very lucky to have gotten my Clarity right after it rolled off the truck at the dealer. It still had all the transport “goop” all over the paint and plastic all over the inside when I took the test drive.

    Wipers and wiper juice are my biggest issue at the moment. I’m just going to spring for the Bosch replacement as I live in the Seattle area now and good wipers are a necessity.
  11. Clarity_Newbie

    Clarity_Newbie Active Member

    Casey Martin
    Very interesting that this also happens with relative high SOC.

    Couple quick happen to know if the Clarity went into EV mode (or at least the EV light came on) while you were "coasting"? Can you recall if the engine clutch light (gear icon) was on just prior to when the vehicle started coasting?

    The reason I ask is in my Clarity the EV light tends to comes on in scenarios similar to yours...which may be informative because of the corresponding RPM drop which will cause the engine clutch to "disengage" if in fact it was engaged.

    I am in the middle of researching RPM's relative to when the engine clutch engages/disengages. The preliminary info indicates the engine clutch engages when the Clarity is already up to speed which indicates to me it is designed to maintain vehicle speed as the primary function...not to provide power for quick acceleration. This may explain why the clutch will stay engaged during the slightest of inclines but disengage on significant inclines when the request for more power is made.

    This may also help explain why some folks see it for long distances and others don't. If you have a steady foot on the throttle and maintain RPM's or run cruise control...the engine clutch stays engaged for miles. If you are the type to constantly speed up or change lanes ask for more power...then it may engage/disengage frequently.

    As an example...on my 45 mph the data indicates the engine clutch engages at ~1600 RPMs and stays engaged +/- 5% of that RPM before it disengages. I also have data taken at 60 mph which indicates similar ratios at that speed as well. I am looking at a host of inputs trying to find commonality. This will take time. Results to date are very preliminary.

    I'd appreciate it if you can provide me with any pre-high rev experience info.

    Good luck.
    Last edited: Jan 26, 2019
    tom kirshbaum likes this.
  12. Clarity_Newbie

    Clarity_Newbie Active Member


    Sorry to hear about your issues. I have a couple of quick questions if you don't mind.

    You are also the second person I know of who reports this issue at 7000 miles. Do you know approximately how many ICE vs EV miles are on the car?

    Can you recall if the engine clutch (aka gear icon) indicator was on in the energy flow screen?

    Can you recall if the car was going steady at 70 mph when it switched to HV mode automatically?

    By "suddenly" you mean almost as quickly as it went into HV mode on its own...then the car lost power? Any time lag?

    I am researching RPM's and engine clutch engage/disengage in my spare all info is helpful.

    Thanks in advance.

    Good luck.
    Last edited: Jan 26, 2019
  13. ab13

    ab13 Active Member

    You should post a complaint at the site. Did your car have all the software updates?
    David Towle likes this.
  14. Casey Martin

    Casey Martin Member

    I did not notice but I will keep an eye on it. I will try to remember to turn on HV mode every time I cross through that toll booth. I go through it 5 times a week so hopefully I can duplicate the issue. If it happens again I will check to see to if it switches to EV mode when it happens. I have tried to duplicate it a few times since it happened but I wasn't able to. I will make a conscience effort to turn on HV mode every time I go over the bridge going forward and hopefully I will be able to duplicate it. Since the ICE was screaming when it happened I assume it did not switch into EV mode but you never know.
  15. Clarity_Newbie

    Clarity_Newbie Active Member

    Casey martin

    Thanks for the reply. I was asking if the car went into EV mode while you were coasting..which effectively brings RPM's to 0.

    The way I interpreted your write-up...once you went through the then hit the throttle which activated the ICE. I should have been more clear.

    Keep us posted. Thanks
  16. insightman

    insightman Well-Known Member

    If the engine is racing, then the clutch is not engaged, or you'd be the first Clarity driver to feel the car's full 212 hp being used to accelerate (assuming you've got the traction motor contributing, too). Both battery charging and discharging occurs in Engine Drive mode (when the clutch is engaged).

    Last edited: Jan 26, 2019
  17. Casey Martin

    Casey Martin Member

    Now I understand what you mean. I will watch it while coasting through and when I begin to accelerate.
  18. Casey Martin

    Casey Martin Member

    That makes perfect sense. I didn't do a very good job of explaining it. lol

    So when the clutch is engaged the engine RPMs should correspond with acceleration? I believe the clutch can only engage around 50 mph?
  19. insightman

    insightman Well-Known Member

    I believe 45 mph is the minimum speed for the clutch to engage because the gearing for the single-speed transmission is like a 6th gear in a multi-speed transmission. After the clutch engages, I've been able to keep it engaged with my speed as low as 41 mph, but I haven't tried to see how fast I can go in Engine Drive mode.

    Note that in the diagram, the speed of the Clarity doesn't change while in Engine Drive mode, indicating it's expected to be used in a speed-holding action rather than accelerating. That sort of makes Honda's claim of 212 hp bogus because when you're accelerating full-out, you have only the 181 hp from the traction motor being fed from both the battery and ICE-driven starter motor/generator.
  20. MPower

    MPower Active Member

    I have seen the clutch engaged on relatively flat interstates at 65-68 mph. It seems to be perfectly happy to stay engaged as long as you don't ask anything of it. It even stays engaged on slight upward inclines as long as you have plenty of momentum and don't have demands. I think your theory of "speed holding" is correct--but maybe we should call it "power holding". If you ask it for more power, either for more acceleration or hill climbing, the clutch will disengage.
    insightman likes this.

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