Strange ICE behavior

Discussion in 'Clarity' started by Rajiv Vaidyanathan, May 3, 2018.

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  1. jerry50902

    jerry50902 New Member

    @M.M.

    Tbh, it really doesn’t matter how the Clarity, or any EV works. Getting to the bottom of the problem is not needed, as long as a fix is provided in some manner. In reality, it is burning excess fuel that wasn’t needed. I know for a fact that the Volt does not do this.

    If it is a design flaw by Honda, it needs to be fixed. It’s that simple.
     
    bobcubsfan likes this.
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  3. bobcubsfan

    bobcubsfan Active Member

    I agree. Honda should reimburse us for unnecessary fuel burned. The EPA should know as well.
     
  4. bobcubsfan

    bobcubsfan Active Member

    BTW there are 2 threads with this issue. Can the moderator or administrator combine them?
     
  5. Viking79

    Viking79 Well-Known Member

    No they shouldn't, the EPA range is 0 to 47 miles.

    I agree it should be changed, but the car is a PHEV and not an EREV.
     
  6. bobcubsfan

    bobcubsfan Active Member

    Another post says the Volt does not do this. If so, it is virtually the same technology as the Clarity. So what gives?
     
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  8. Viking79

    Viking79 Well-Known Member

    I agree, the Clarity should drive like the Volt. However, Honda decided to make it a hybrid with EPA 0 to 47 mile range instead of like the Volt, electric vehicle with EPA 53 mile range and then switches to gas.

    I am just saying Honda isn't doing anything wrong per their EPA range, but we should push them to see if they can disable engine starting while full within some margin. Like driving down short hill shouldn't start the engine, but maybe driving down a mountain would (Volt has issues after around 0.5 or 1 kWh added in regen while full).
     
    Kendalf likes this.
  9. bobcubsfan

    bobcubsfan Active Member

    Did not see any info that says 0 - 47 mile range.
     
    Johnhaydev likes this.
  10. jerry50902

    jerry50902 New Member


    I wouldn’t go as far as that. Just want the problem solved.
     
  11. bobcubsfan

    bobcubsfan Active Member

    Tongue firmly in cheek. Just trying to get Honda's attention, if they in fact, monitor this forum.
     
    Johnhaydev likes this.
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  13. megreyhair

    megreyhair Active Member

    I need to report another strange ICE behavior.
    The batt was near full. Car in EV mode. Climate control set to 70F. City traffic. ICE came on and the blue ring turned white in dash. ICE ran for a few minutes. Stopped when I stopped at a traffic light. It never came back on again during that trip. But the ring never change back to blue. I toggled the mode mode a few times and the ring did a partial blue ind HV mode. But turned back to white in EV. The strange thing is that the ring ever changed back to mostly blue.
     
  14. lisaandadam

    lisaandadam New Member

    I'm so glad I'm not the only one seeing this issue. I agree with jerry50902 in that if Chevy has found a way to not run the engine when the battery is full then Honda should be able to do the same. I'm going to reach out to my dealer but I don't have a lot of hope as the sales guy didn't know a lot about the car and when I dropped by the service department (SiriusXM not working) the guy that met my car didn't even know what model I had (he thought it was an Accord but was confused because "it didn't quite look right"). I love the car, it's so much roomier and comfortable then our Volt and the ACC/LKAS are pretty amazing but disappointed in the drive train if this can't be fixed.
     
    Johnhaydev likes this.
  15. M.M.

    M.M. Active Member

    I talked to a couple of knowledgeable co-workers and did some additional research and can at least shed a little more light on what other cars do in the "full battery downhill" situation.

    Nissan Leaf
    As a full EV, these will let you charge the battery to true 100%, and can also be programmed to stop at 80%. My co-worker who lives at the top of a long hill and owns a Leaf informs me that if you charge to 100% then go down a long hill the regen will just quit after a bit, when the battery is in danger of overcharging, and you're left to use mechanical braking. You can feel it at that point. Telling the car to stop charging at 80% or cranking up the heater to burn excess energy are ways of manually avoiding or mitigating.

    So that one makes perfect sense--as a pure EV there's nowehere else to put the energy other than the heater or brakes.

    Plug-in Prius
    These have a full transmission, and according to my knowledgeable co-worker they will start the engine when the battery is really full, and use compressive engine braking at that point to augment the mechanical brakes. Makes sense because of how the transmission is configured.

    Chevrolet Volt
    The Volt's ICE is physically capable of being linked to the wheels, but is only designed to at speeds over 70mph (full drivetrain description here). Per Chevrolet themselves, what the Volt does is really interesting. The car has a smaller 55kW motor-generator whose primary purpose is generation from the ICE, but is connected to the wheels above 70mph with an appropriate-ratio gear in order to increase EV efficiency at high speeds. With a full battery, the car connects both electric motors to the wheels and dumps energy being generated from the main motor into the secondary one. Since the motors are actively cooled (they apparently have their own radiator), it can dump about 12kW of energy into the electric motors as a means of bleeding off energy to augment the mechanical brakes without ever needing to bring the ICE online.

    A forum thread elsewhere quotes a response from someone at Chevrolet explaining this. This post in that same thread is someone who actually tested this and verified it with the car's computer. The specific message:

    Clarity
    This one's the question mark at this point. Since it has a mechanical transmision, it could theoretically do what the Prius does. Since the drivetrain as I understand it is somewhat similar to the Volt's, it's also theoretically possible to do what the Volt does. Or it could do the wacky third option and use the generator to put load on the ICE. Or it could just force you to rely on the brake pads like a pure EV. Which of those it actually does is anybody's guess until someone supplies more concrete info, but...

    ...the real question is whether it's inappropriately using the ICE to actually provide energy--rather than just waste it--in some circumstances, which is what some of the posts in this thread seem to be describing. If so, that's a bug, and should be fixed. One acceptable way for a PHEV to provide supplementary braking on a full battery is to use compressive braking in the ICE, but inappropriately generating power with the ICE is wrong behavior.

    Since I don't have anywhere to charge at the top of a hill I can't really test this myself or experiment. I did try putting it in HV Charge mode with a full battery and driving up a hill, goosing it to encourage ICE use, but the car fairly aggressively used battery energy until the SOC was about 90%, and I only had enough hill to charge it back to about 95%.

    That's kind of the point of getting to the bottom of it--depending on exactly what the car is doing, it might not be a design flaw, just not the behavior people are expecting. Conversely, it might be doing something logical, but doing it wrong, so it is a design flaw. I've never seen it happen, personally, but I'm curious what's going on and also figure it's useful to know what, exactly, is happening, in order to distinguish between unexpected behavior and an actual car software problem.

    I'm going to post a poll to try and gather a bit more data.
     
    lorem101 and KentuckyKen like this.
  16. KentuckyKen

    KentuckyKen Well-Known Member

    M.M., thanks for the great information and starting the poll (just took it). This will certainly help us figure out what our Claritys are doing. Keep up the good work!
     
  17. nayagan

    nayagan New Member

    I am new to this forum and exactly having the same issue. In normal driving conditions, just out of home whether within 1-2 miles or well over 10+ miles, my clarity keeps jumping into ICE mode for no reason. Can't figure out why its happening. Someimes it goes back to EV on its own and sometimes have to stop/restart the car to get it back to EV mode.

    I see this thread was 1+ year old, what was the solution determined for this ? Anything dealer could do to address this ?

    Also I keep getting weird humming noise while the battery is charging at home. Is this normal ?

    Thanks all.
     
  18. jdonalds

    jdonalds Well-Known Member

    nayagan, your situation may not match this but it is a common cause. If you begin driving with a 100% full battery and then proceed to go down a hill the car will try to use regen to store power while descending the hill. However there is nowhere for the energy to go because the battery is full. So Honda's solution is to use the generator to spin the engine to dissipate that energy.

    My situation is such that we have a 14% downgrade 1/2 mile long when driving away from our house with a full charge. However that hill is 1 mile from our house so the car burns just enough battery power so that the downhill regen does find enough empty space in the battery for that regen power. So in our case the engine doesn't start and the car stays in EV mode.

    YMMV,
    John
     
  19. bobcubsfan

    bobcubsfan Active Member

    The issue is inconsistent behavior. Sometimes ICE comes on, sometimes it does not in identical situations.
     
  20. The Gadgeteer

    The Gadgeteer Active Member

    I have had the ICE come on flat if after a 100% charge I accelerate hard to end of the block then immediately do full regen. My new SOP is gently drive/slow down until I have traveled a couple of miles.
     
  21. bobcubsfan

    bobcubsfan Active Member

    To be clear, ICE comes on, or not, with exactly the same route, temperature, full charge. Inconsistent behavior is the issue. Not that ICE comes on. Completely unpredictable.
     
  22. MNSteve

    MNSteve Well-Known Member

    I have observed "inconsistent behavior" on the Clarity, but I put it in quotes because I don't think it's inconsistent. The fact that we cannot predict it does not make it inconsistent.

    There are many different parameters that are inputs to the software that controls how the car works. Some of them are obvious; we can't even guess at what some of them are. I am confident that the result is completely predictable if we had all the inputs because computers are deterministic.

    My personal bugaboo is the gear icon. I can drive the same route at the same speed with the same weather conditions and observe very different behavior in terms of when the gear icon is displayed. But I am not privy to all the inputs. SOC has an effect, as does what the SOC was when I hit the HV button, and the net in/out of charge in the past time interval . . . and I don't know what the time interval is. I am sure that there are other factors that go into the algorithm on how to configure where the energy is coming from to propel the car. Given our inability to even know what those are, much less observe their value, it's going to look like magic to us.

    I try very hard not to get upset when the car doesn't behave exactly the way I would predict.
     
  23. Danks

    Danks Active Member

    We are a new owner. We've done a few days running EV only - enough to get our estimated EV range up to 50 after charging this morning. On the freeway - 70 mph - on the way home in EV my wife noticed that the ICE was running. As she remembers it, the energy was going from the ICE and battery to the wheels. This was only a few miles into the trip and lasted only a few miles. Fairly level west MI road. Our HV range dropped from 231 to 225.

    It was around 90 degrees here today so the AC was running. Would this cause the ICE to run?
     

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