Impressions from an 800 mile trip

Discussion in 'Clarity' started by LAF, Jul 10, 2018.

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  1. LAF

    LAF Active Member

    I bought the Clarity mostly to drive it all electric, which has been terrific. But I tested it as a midsize hybrid by taking my first long trip. It was to and from Boston and Mont Tremblant, Canada in 3 days. It was challenging given the extra time spent waiting to cross the border each way and dealing with major construction around Montreal, which led to ~an 8 hr trip each way. My most important impression was that the trip was much easier than I expected because the car was so comfortable and I got to take advantage of some of the technology features that hadn't made much difference around town.

    I had debated whether to get the touring model because I didn't necessarily need power seats and could use my phone for navigation. However, the extra money really payed off because changing seat positions along the way made the trip much more comfortable. In addition, the navigation worked in Canada so I didn't have to pay for roaming charges using Google maps on my phone.

    The adaptive cruise control really made the long stretches on highways much more comfortable. And even the steering assist on roads that were not particularly curvy (where you do need to actively steer) made the trip more relaxing. Also, I have always felt a good handling car made you feel like it anticipated turns. This is exactly what the steering assist feature does, which added to its effectiveness on the long trip.

    One weakness I observed on this trip, but not on flat ones (we crossed the White Mountains in NH going and the Green Mountains in Vt coming back) was that despite keeping the car in HV the whole time the climbs reduce EV capacity. I did have enough to drive EV around Tremblant, but since I couldn't charge the car there I lost all EV on the way back. As others have observed, this makes climbing hills more noisy, but I didn't feel the car lacked power. I did some EV charge to help, but I that just keeps the engine on in flat parts of the trip and you need to keep it going for an hr to make a real difference, so I didn't bother.

    But overall, this is a great car not only in EV but also as a hybrid for long trips.
    atr, nymphaeles, ClarityDoc and 4 others like this.
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  3. LAF

    LAF Active Member

    by the way, the fixed HV range indicator was spot on which helped because we came home with 2 bars left, which meant after fill up that 1 gallon of gas was left and the meter read 40 miles to go!
    Carro con enchufe likes this.
  4. PHEV Newbie

    PHEV Newbie Well-Known Member

    Thanks for the detailed report. Actually, your experience is similar to mine but I would say that it reflects good tuning of the HV mode. The ICE only puts out 103 hp. Imagine how little power you would have if the battery was depleted and it fully relied on the ICE to provide the electricity for the climb. The engine would have to rev near the redline (Angry bees? More like an angry wasp colony!) and it still would have a hard time pulling 2 tons up a long, steep incline. With a significant charge, the car uses both the ICE and the battery, providing sufficient power and reducing the rpms the engine would need. What I generally did was simply go to HV charge when I'm on an easy stretch (moderate speeds plus flat or downhill terrain) after it's depleted from a climb. It also reflects why one should also maintain a significant charge in HV mode. After compiling information from professional reviews and posts in this forum, I think state of the battery charge is the difference between numerous reports of 46 - 52 mpg vs reports of 36 - 42 mpg in HV mode (after factoring out speed).
  5. Carro con enchufe

    Carro con enchufe Active Member

    We used ours for a beach trip last month and my wife was pleased with how comfortable the car was and how much fit in the trunk. Much more room than her SUV, double the gas mileage in hybrid mode, and charged at our destination for all electric local driving
  6. LAF

    LAF Active Member

    I agree, but the car could have been programmed to keep EV range constant automatically when in HV mode regardless of terrain .
    insightman likes this.
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  8. Viking79

    Viking79 Well-Known Member

    I think HV mode tries to hold range, but won't actually charge, is that what you are saying? If you want to maintain EV range for later in hilly areas where you might regularly exceed the limit from the engine, use HV charge mode and it will keep the battery at 58% or whatever it does when it has excess power capacity to charge. Turn it on early enough so the car doesn't have to charge up to 58%.

    Thanks for the report!
    ClarityDoc likes this.
  9. LAF

    LAF Active Member

    Here is what is in the manual- It says it maintains the battery charge-

    HV Button
    You can enable HV or HV Charge by pressing the HV button.

    The HV indicator comes on regardless of which source you have enabled. If you press the HV button again, or set the power mode to VEHICLE OFF or ACCESSORY, the source you have selected will be cancelled.
    ● HV
    To enable HV, press the HV button. In HV, the engine may run at times to drive the generator so that battery charge levels can be maintained.

    The graph below it in the manual affirms this concept. It works on flat but not hilly terrain. Maybe this can be programmed in after the fact.
  10. PHEV Newbie

    PHEV Newbie Well-Known Member

    From what I've seen in HV, if you're just on the highway with flats and rolling hills, it can go to full electric (presumably when most efficient) expending a few miles and then recharge at some point after. I've also noticed that if you gain a couple of excess miles going downhill, it will go EV to expend it even if that's not necessarily most efficient. On a drive from PA to the Outer Banks, it cycled continuously and maintained the charge (maybe losing just a few miles overall).
    KentuckyKen likes this.
  11. insightman

    insightman Well-Known Member Subscriber

    The graph on that page (see below) indicates HV Mode will maintain the battery charge. The battery charge decays when HV Mode is disabled. So the question not addressed by this graph is: What level of battery drain cannot be recovered by HV Mode?

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  13. KentuckyKen

    KentuckyKen Well-Known Member

    Like PHEV Newbie, on a 500 mile round trip with some mountains, in HV Mode starting with a full battery, the SOC was maintained (losing 1 bar and 3 miles) and the power flow showed cycling through every possible power flow. Kept my EV range and never heard the angry bees. Just on one long climb, the ICE reved up to a low hum and that was the only time it was really noticeable. And I got 49 mpg!
    Will post details; still crunching numbers.
    Last edited: Jul 10, 2018
    Johnhaydev and PHEV Newbie like this.
  14. Mikeinohio

    Mikeinohio New Member

    I'm sorry, but I'm easily confused. Are you saying on long highway trips you stay in HV mode the whole way? If so, in HV mode does the ICE cycle on and off or run continuously? Do you go to HV mode immediately or when the HV battery gets low? What mpg do you get in HV mode? I have not seen a good explanation of how to best utilize HV mode.

    I test drove both a Clarity and an Accord that both had discharged batteries and on the highway at 55 and 65 mph I was only getting about 36 - 38 mpg. That left me suspicious of the mpg rating. I suspect the Clarity ICE was working overtime to regain some charge in the battery, but I'm not sure what to make of the low mpg on the Accord. Any explanation would be appreciated.
  15. LAF

    LAF Active Member

    On trips longer than 50 miles the idea is to put the car in HV mode as soon as you get to the highway and it behaves like typical hybrid cars. The engine goes on and off but you don't hear it on the highway even as quite as the car is . I got ~40 mpg which is quite
    remarkable for a big car like the Clarity. Normally this keeps the existing EV capacity where it began (it good to start with a full charge). This is good because on some hilly stretches the car does best with more than the base level of EV charge below which the car never goes. It is also good because when you get to your destination you can drive around town in all EV.

    My point was that in very hilly terrain HV mode lets the EV charge go down. So on some very hilly stretches with the base EV charge the engine has to run at higher RPM and you do hear it. I thought the car should be programed to recharge the battery to the level you started with no matter what.

    You can get around this if you plan ahead on the level stretches of putting the car in HV charge mode which increases the EV capacity so the engine doesn't have to go to high RPM going up big hills.
  16. KentuckyKen

    KentuckyKen Well-Known Member

    Here’s my post from another thread that elaborates on some of what your asking.

    I think our HV mode is better than the Prius since on the highway, our ICE doesn’t have to run all the time.

    If you want to avoid the buzzing angry bees and always have plenty of power for hills, all you have to do is not let the HV battery completely deplete down to 0 EV range and 2 bars.
    For level roads, moderate acceleration, and normal speeds you can get by with using up all your charge and letting the car automatically switch to HV.

    But on the highway, and especially with hills and higher speeds, the car likes more than the 2 bars to be able to cycle through all of its possible power flows to be able to deliver the most efficient, quiet, and required power.

    On a recent 500 mile round trip with both Interstate at 70mph and hilly 2 and 4 lane very hilly roads at 60-70mph I started in HV with a nearly a full charge. I watched the powerflow cycle though battery only, battery plus generator, regen, generator charging battery, engine direct to wheels, all seemlessly done as far as felt power and drivability. I got 49 mpg and lost only one bar of EV so the mpg was not inflated by using charge. Some times I would see the charge/EV decrease by as much as ~3 bars/15m but then gain it back as the computer decided when use the battery and when to recharge it. Also I have an hour meter and calculated the ICE ran about 2/3s of the trip and cycled on and off repeatedly and rather frequently.

    Best of all, I never heard the buzzing angry bees! Before this trip, I had to slow or stop the car and turn off the AC to be able to hear the ICE idling and only once on my first fairly level Interstate trip did I hear it make kind of a fast idle in HV. On this trip at the end of a very long, steep hill, the ICE did rev up to a low to medium hum but not the buzzing angry bees. But at no time did I ever experience a loss of power.

    So bottom line, you need some charge in the “bank” for the algorithm to be able to use all it’s possible powerflows in the most efficient and quiet manner. I would suggest switching to HV on highways before you run out of charge, say around 1/3 to 1/2 unless you know you’ve got mountains ahead and then I’d want a full charge by switching early. When you run down to 2 bars ans 0 EV, you can run into situations where the car is limited in what powerflows it can chose and you’re more likely to get the angry bees and driveability issues.

    And the only use for HV Charge I can see would be if you are on a highway and approaching mountains with not enough charge.
    This is the best car on the road and I want to end the angry bees for all.
    ClarityDoc likes this.
  17. Mikeinohio

    Mikeinohio New Member


    That really helps, but can you now explain what you mean by "HV charge"? As I understand the HV mode there is a short push and a longer hold of the HV button. When do you use each one and what is the difference in function?
  18. PHEV Newbie

    PHEV Newbie Well-Known Member

    Car and Driver recently fully instrument tested the Clarity and got 46 mpg going 75 mph on a standard loop in HV mode ( ). That handily beat the smaller Chevy Volt on the same test and was nearly as good as the Prius Prime (2 of 3 trims). I did even better going more slowly at 50-65 mph in HV and losing no EV range. Every time I experienced great mileage with the Clarity, I had a significant charge (more than half) and conversely there seems to be a strong correlation of poor mileage and a depleted battery as you discovered yourself. I suspect Car and Driver did their test with a significant charge because the faster you drive, the worse the mileage in hybrid vehicles. The lesson is to keep a significant charge during road trips if you want excellent gas mileage.
    atr, lordsutch and bwilson4web like this.
  19. weave

    weave Active Member

    I have to regularly drive 200 miles, mostly freeway. The way it goes is, drive through a small town, drive on a US highway with no stop lights at 55 mph, then go through another small town, then onto the interstate until I get near my destination, then stop and go through suburbia until I get to the end.

    I start off with full charge, drive EV through the first town, then HEV on the US highway, then as I approach the second town I switch back to EV, then on the Interstate switch back to HEV until I get near my destination. If I still have about 1/2 EV range left, I'll switch back to EV and ride it to the end.

    That seems to work really well and my highway miles have plenty of battery left to help those miles run smoothly.

    So yeah, in HEV it tries to maintain the charge. So occasionally I'll see the energy flow from engine to wheels and engine to battery until it can get it back to its baseline, then go back to battery and engine both driving the wheels.
    insightman and Johnhaydev like this.
  20. Greg DoClose

    Greg DoClose New Member

    Possible future answers on driving across states w/Honda 2018, Clarity Plug-in. Just did a 1,758 mile trip w/ 36.91 gallons of gas used. So ave., 48 mpg. I found out that one time per day was real-world to charge up. I kept the car in Hybrid mode all the time except go up hills or around town. Hybrid would try to feed power back into the battery but it would slowly move downward on Long driving. So it was easy to find gas I would simply hold down the hybrid to charge mode, and charge it up to its maximum level which is 58% or 12 bars.
    Last edited: Jul 29, 2018
  21. Greg DoClose

    Greg DoClose New Member

    Edited the top on driving long distance: With my Honda 2018 Clarity Plug-in, did a 1,758 mile trip w/ 36.91 gallons of gas used. So ave., 48 mpg. I found out that one time per day was real-world to charge up. I kept the car in Hybrid mode all the time except going up hills or around town. It would also use gas to charge up the battery but EV slowly move downward on Long driving. As it was easy to find gas, I would simply hold down the hybrid to charge mode, and charge the battery up to 58% or 12 bars.
  22. KentuckyKen

    KentuckyKen Well-Known Member

    OK, I’ll give it a shot
    HV (press HV button once) will cycle through all power flows using the ICE and battery in multiple combinations to attemp the most efficient propulsion while approximately maintaining your current charge level.
    HV Charge (hold HV button) will run the ICE to attempt to both propel the car and simultaneously charge the battery up to about 58%. HV Charge will therefore be noisier and yield reduced mpg but will give you a charged battery “on the fly”.

    The only use I can see for HV Charge is if you’re approaching mountainous terrain and are low on charge. The car will climb better and sound quieter if it has some charge versus trying to do so with little or no charge. It really hamstrings the car’s ability to be able to use all of its possible power flows if you don’t have a sufficient charge to begin with.
    Johnhaydev and insightman like this.

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