ICE, RE-GENERATION and the BIG HILL (A Novella in Three Acts)

Discussion in 'Clarity' started by K8QM, Jun 5, 2018.

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  1. K8QM

    K8QM Active Member

    All my usual caveats hold - YMMV!

    At least once a day since late February I have pulled our Clarity out of our garage, driven about 150 feet up our gravel driveway and then headed down a hill approximately 2/10ths of a mile long. In well over a hundred trips I've never had the ICE come on due to the regen process causing the car to need to "shed load" as it would be called in the power industry.

    So today I decided my daughter and I needed some weird science.

    Act One
    When I got home from work I fully charged the car on the level 2 charger, drove it once around the neighborhood to shed some charge and parked it pointed downhill on the side of our road. About 75 feet of extension cord got the Honda charger out to the car where I topped it off from 98% to 100%.
    Once we hit 100% we unplugged, turned off HVAC, radio and lights and started rolling down the hill. We were in regen the whole way, but once I started applying brakes at the bottom the ICE kicked on. Note again that this has never happened before, but the simple difference of not having the 150 foot drive up our driveway would seem to have made the difference in how much charge the battery could take.

    Act Two
    After driving around long enough for the ICE to warm up fully I repeated the level 2 charge, this time going directly to my roadside parking place instead of doing a loop around the neighborhood. When I plugged in the level 1 charger nothing happened; presumably the battery was not even down 1% and would take no charge.
    So I repeated the roll down the hill, but instead of only applying brakes at the bottom as I normally would I applied them as much as possible the whole way down and indeed was able to get the ICE to start up. This lends credence to those that say braking provides more regen than just rolling and also shows that everyday I'm probably just a couple of brake taps away from starting the ICE when I leave home.

    Act Three
    After driving around long enough for the ICE to warm up fully I repeated the level 2 charge, drove it once around the neighborhood to shed some charge and parked it pointed downhill on the side of our road. About 75 feet of extension cord got the Honda charger out to the car where I topped it off from 98% to 100%.
    Once it was fully charged we unplugged, cranked the heat on HI, turned both seat heaters on full, waited about a minute and then repeated the roll test with as much braking as possible.
    No ICE, only silent running in EV.

    *I'm stepping on my soap box here*
    So, a non-scientific experiment, but I think the results are valid and show that although we often make assumptions that things are happening randomly, they may very well be working exactly as designed. That design may not be well thought out or it may not fit our view of how something should work but it doesn't make it wrong.

    Even in the case of the annoying as heck HV readings there is a case to be made that some Engineer thought it would be really clever to average all your driving into one reading. That could be valid for some drivers but certainly not for the vast majority of us and luckily Honda has gotten the word.

    It could be that the Clarity needs to charge to 99% of what it does now to allow some regen space or maybe the max charge needs to be 101%. That's for someone smarter than me to figure out.
    *Off the soapbox*

    Comments and questions welcome.

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  3. KentuckyKen

    KentuckyKen Well-Known Member

    K8QM, I nominate you for the inaugural Clarity STEM Award.

    I think you did as well could be done outside of having a test track, an unlimited supply of time, and a bevy of engineers. Your reasoning seems sound and seems to agree with my experience and other post’s observations.
    I think we now have pretty much confirmed the “limited regen, ICE operation on a full charge when BMS will not allow any current flow into the HV battery scenario”. Thanks for peeling back a little more of the onion of mystery for our Claritys.

    Now we just have to come up with a catchy short descriptive name for it! I’m stumped. Perhaps another contest?

    And in the interests of verifying the reproducibility of your findings, we’re all 3 trips made with or without the groundhog under the hood?
  4. Viking79

    Viking79 Well-Known Member

    I will try this as well as close as I can. Now that you mention the brake, that is when the engine started for me too when I was slowing for a roundabout. I have noticed for a long time the higher level of regen with braking (more movement into green of power needle), but never thought of it being tied to engine starting. Great detective work :)
  5. Sandroad

    Sandroad Well-Known Member

    Interesting! Although we don't live on a hill and don't have a resident groundhog in the engine compartment (all ours are in their proper locations under our shed), ACT 1 and ACT 2 mirror our experiences when the ICE has started.
  6. insightman

    insightman Well-Known Member Subscriber

    Premature enginulation
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  8. KenG

    KenG Member that’s what I have been saying....just not so eloquently or with science thrown in. Best I can tell... with all of the complaints I have heard from early adopters.... No one has broken down....Because of the panic though our cars are going to be panned in the press.

    Sent from my iPhone using Inside EVs
  9. K8QM

    K8QM Active Member

    BTW Now that I've had some dinner and reflected a bit I want to make clear that the purpose of my test and post was in no way meant to minimize any annoyances some of the forum members are having. In fact I am now 100% sure that if the state put a stop sign at the bottom of my hill I would be having the problem instead of rolling along blissfully ignorant of how close I'm coming to premature enginulaation (curse you @insightman).

    My point is that if someone goes to their dealer and says "My engine's coming on randomly for no reason and you guys need to fix it." the mechanics are going to be left scratching their heads even if they do want to help. If instead they can say "Hey there's this idiot in North Carolina that did an interesting test and it turns out that it seems to be the reason my engine comes on every morning and Honda needs to be aware of it because it's making for some very unhappy Clarity owners." then maybe they can get some traction like on the HV issue.

    The Multiple System Warnings is a whole different issue since it doesn't seem repeatable at all it is going to be a bear to fix.

    God bless the early technology adopter for we know not what we buy.

    Viking79 and KenG like this.
  10. ClarityDoc

    ClarityDoc Active Member

    I really like @insightman's "premature enginulation".

    Descriptive alternative: "ICE from overflowing juice box"
  11. bobcubsfan

    bobcubsfan Active Member

    Great experiment. In my case, I fully charge the Clarity. No heat or a/c or anything else going. Back out of the driveway, go downhill to first stop sign, about 300 feet. Step on brake hard. No ICE. Turn right to second stop sign, about 300 feet. Break hard. No ICE. Turn left then right to 3rd stop sign, about 3/10 miles. Break hard. sometimes the ICE comes on. Sometimes it doesn't.
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  13. K8QM

    K8QM Active Member

    I know you've been dealing with this for quite a while. Is there any way you could possibly vary your route to get either always comes on or always doesn't?
    I have to say I was a little shocked that just changing my braking habit on the hill was enough to start the ICE.

  14. Viking79

    Viking79 Well-Known Member

    I tried to replicate today and failed, but sitting in car for a bit, loading kids, etc, so will try again next time.

    One thing I notice is that braking on a full battery uses much less regen than braking on a partially charged battery. My first few stops used only friction brakes according to power needle.
  15. bobcubsfan

    bobcubsfan Active Member

    Hi Geo,

    I have varied my route again with mixed results. As you point out, you have to start "fresh" each time. Full charge. So, you either wait until you have to drive again, or charge the car and take it out again.
    Johnhaydev likes this.
  16. Steven B

    Steven B Active Member

    I've documented my charging enough that I am now able to set the charge schedule daily in the app to stop shy of 100%.
    Kendalf and K8QM like this.

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