New owner, some general questions

Discussion in 'Clarity' started by Dislin, Oct 25, 2020.

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  1. Dislin

    Dislin Member


    I haven't seen these directly addressed.

    1. In EV/eco mode, what acceleration behavior is best for efficiency? Like in traditional ICE cars, it can be beneficial in some situations to get into the higher gears faster. Is the Clarity at its most efficient with the least amount of throttle in EV mode?
    2. Similarly, what kind of regen braking behavior is the most efficient? Is there any point to the paddles if you're not going downhill?
    3. I'm hearing that the heater has pretty massive battery usage. How does it behave? Is it better to turn the climate control on/off as needed, or better to leave it as low as possible, but keeping it on?
    4. What is best to wash the car, touchless machines? Anything else I should know about?

    I might have more questions later, but thank you!
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  3. jdonalds

    jdonalds Well-Known Member

    1) I think speed is more important than acceleration. I haven't noticed too much difference between aggressive jack-rabbit starts or not in terms of battery drain. Your battery charge will last longer if you are in areas where your speed is closer to 35 mph than 60 mph. As always a steady speed without much acceleration or braking is best.

    2) I use the paddles to slow down quite a bit. General thinking is the paddles do not engage the physical brakes so using the paddles will delay brake pad replacement. Overall it is most efficient not to have to break/regen if possible.

    3) There are two things you can do in terms of cold weather driving. First is to pre-heat the car at home if you have AC power available. Preheating can be done with a 220V L2 charge unit. 110V will work but perhaps only if the battery is close to fully charged. So if you leave home with the interior of the car warmed you can leave the climate system off and just use the more efficient seat warmers which can go a long way to keeping you warm. Last result is to turn the heat on. If you're driving in HV mode the engine can supply some heat preserving the battery.
    PHEVDave, insightman and ClarityDoc like this.
  4. MrFixit

    MrFixit Well-Known Member

    I understand the principal of preheat for comfort and not jumping from your warm bed into a frigid car, but... It seems to me that kilowatts are kilowatts. From an efficiency / cost of operation, preheat doesn't save you anything. In fact, it probably costs more since you are heating an empty vehicle for a period of time.

    As @jdonalds points out, some find that using the seat heaters allow you to be comfortable without having to set the heater as high.

    In my opinion, if you are on a longer trip and are operating in HV mode, the heat is then 'free' (well, no different than a conventional vehicle where the cabin is heated from wasted engine heat) so crank it up !

    It's all a matter of comfort. If your priority is saving energy then bundle up and don't use the heater. If you want to be comfortable, then use the heat and accept a shorter range. The heater work very well, but does shorten the range substantially.
    insightman likes this.
  5. I believe the theory behind the practice of warming the interior of the vehicle while on shore power is to remove that electrical demand from the battery while driving, thus preserving the full charge on the battery which may yield a few additional miles of EV range.

    Cost difference is probably somewhere between a wash and insignificant. It may even be more efficient to warm the car in a garage that is 10-15F warmer than outside temperatures.
    petteyg359, Pooky and gedwin like this.
  6. Danks

    Danks Active Member

    110V works fine as long as the car isn't charging. So either fully charged, or the charge has been stopped. We plug in at night, stop the charge, and the pre-condition in the morning all the time. We need 12.5 miles EV for my wife to get to the free chargers where she works. Pre-conditioning works fine with only that much charge as long as charging is stopped.
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  8. DrDeke

    DrDeke New Member

    I just bought my Clarity (2018 model year) yesterday, so this isn't backed up by long experience or anything.

    1) I read a paper some time ago about EV efficiency (I do not remember which model of car it was talking about though), which showed that gentle/low-power acceleration was still more energy efficient (due to both motor and battery performance considerations) than hard/high-power acceleration. However, the difference was not huge. Also, on the far left and right of your dashboard, there should be two colored indicator bars/curves which [in EV mode, at least] will be green if the car thinks you are accelerating efficiently, and whiteish if it thinks you are accelerating hard enough to be inefficient.

    I think I am a fairly average driver in terms of soft vs hard acceleration, and I find that when driving in town, I rarely am inclined to accelerate hard enough to turn the bars white. On the other hand, starting from a stop on 55 mph limit streets, I do tend to get into the white zone from time to time.

    2) I have read conflicting opinions here and elsewhere about paddle vs brake-pedal operation. I do not have anything to add to that discussion at present, but I am hoping I can find some OBD-II PIDs which might shed some light on regen and friction brake operation. If I do, I will make a post here with the PIDs and my findings.

    3) I haven't made any measurements of heater current (hoping to find an OBD-II PID to read that as well), but my heating strategy so far has been to first turn the heated seat to full power, then set the cabin temperature as low as I comfortably can. They are both electric resistance heaters (when in EV mode), but the heated seats consume FAR less energy than the cabin heater for the effect provided. In my climate at this time of year, the windows would fog up quite badly if I turned the climate control system off entirely, so I just leave it on but set as low as I comfortably can.

    4) No idea
  9. insightman

    insightman Well-Known Member Subscriber

    4. Is "touchless" really touchless? I've never tried one out. Whenever I see a car with the edges of the front license plate bent away from the bumper, I always ask myself, "touched or touchless?" I always wash our Clarity by hand. You will not find anyone who claims Honda paint is robust, so some go for a ceramic coating to add protection.
  10. I put ceramic on mine because it scratched easily. I only hand wash even with that on. If the car is "dirty" I'll hose it down to get rid of most of it. That's rare here in Las Vegas since it never rains here.

    Once it's clean I use this to wash it. The 32 ounce has lasted me a year and it's only 1/2 empty.

    It's fast and easy. Put a cap full in a bucket of 2 gallons of water. I use about 1/3 of that and 1/2 a cap full. I just wet thick microfibers, wash, then wipe it off with dry ones. It does an excellent job. Fold them into eighths and refold once a side gets dirty.

    I can do the Clarity in about 20 minutes without hurrying.
    Last edited: Oct 26, 2020
  11. 1. A lot of owners get into maximum mileage from the battery. I take a different approach. I just drive it. Granted I'm usually careful about not getting into the area where the engine comes on, but I find that I do fine re mileage without getting overly concerned. Of course my results aren't as good as someone who lives in the flat lands. Our house is 1000 feet above the Las Vegas valley. Pretty much everything we need is down there. Coming back up that hill kills mileage.
    DaleL likes this.
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  13. Smooth. Light to moderate acceleration, has yielded better than expected (47 miles) EV range on numerous occasions.

    What would you consider “the least amount of throttle in EV mode?” Taking two minutes to get to 50mph? I’m a bit rusty on the rules and regulations of kinetic energy, but it seems that, theoretically, it would take the same amount of energy to bring a 4000lb vehicle from 0-60mph in 10 seconds as it would if we took 30 seconds to bring it to 60mph. So, perhaps the acceleration of the car is less important than what happens after we have accelerated.

    The car has the ability to recapture some, but not all, of the electrical energy that was converted from the battery into the forward momentum of 4000lbs. The most efficient use of that energy would be to allow the car to coast or freewheel as long as possible. I believe that the amount of regenerative energy that is captured will be nearly the same, whether it is used lightly or aggressively. I would actually like to be able to eliminate the built in level of regeneration, 1, sometimes invisible chevron, to see if EV range could be increased even more.

    But, I could be completely off the mark on the whole concept.
    Mark W likes this.
  14. Pooky

    Pooky Active Member

    This is true if you discount the heat losses from discharging the battery at higher currents.
  15. That makes sense. Then we must ask, how effective is the cooling system at controlling that heat? I suppose the same amount of heat is generated by the acceleration, with or without a cooling system. Can those “cooler” batteries provide a bit more power than uncooled batteries?
  16. Pooky

    Pooky Active Member

    I suspect that there would be some difference, since batteries discharge more quickly at lower temperatures, but that difference is probably statistically insignificant for a vehicle of the Clarity's heft. And for the energy that a more powerful cooling system would require, I do not think the tradeoff in EV range would be worth it. Cooling systems have diminishing returns. There's also the fact that the lower the temperature of batteries, the greater the internal resistance, and the less energy that can be stored. I think that this increased resistance would actually cause greater heat losses.
    On that note, while there are greater heat losses from the battery when pushing full throttle than mild acceleration, the difference in efficiency is only ~10% from 0MPH, so a lead foot is hardly the same mileage drainer in an EV as the heater or high speeds. Though the GOM likes to suggest that hard acceleration significantly drains EV mileage, both the battery gauge on the left and my odometer suggest otherwise. It's not something I would be concerned with.
  17. Francofun

    Francofun New Member

    Well, correct me if I am wrong as it has been a while!! What you are describing is the potential energy of the car once it reaches 50mph, which does not change no matter how it came to be at 50mph. However, the amount of energy expanded to get to 50 mph is a function of power over time. The power to accelerate the car faster is not linear and, therefor, you actually expand more energy if you reach 50 mph in 10 seconds vs 2 minutes.

    Does that make sense?
  18. MrFixit

    MrFixit Well-Known Member

    Your expression "power over time" is energy.
    An example is the EV user's most common measurement of energy (Kilowatt Hours).
    Kilowatts are 'power' and Hours are 'time'. When you multiply them you get energy.

    The amount of energy required to accelerate to 50 mph is the same regardless of how you do it.
    There may be some minor secondary factors like resistive losses, etc, but fundamentally it doesn't matter if you do it in 1 second or 100 seconds.
  19. JCA

    JCA Active Member

    Right, was about to post the same -- in an ideal environment the energy consumed to accelerate to a speed is the same regardless of the acceleration rate. And an electric motor is a lot closer to that ideal than a non-hybrid, where the fuel consumed to generate that energy in an ICE varies greatly with RPM (which is why lower speed shifting and CVTs can be more efficient). In a non-hybrid, another big loss is not recovering any energy each time you slow and consuming new energy each time you accelerate again. Storing much of that deceleration energy is why all hybrids are signficantly more efficient in stop and go/city traffic.

    So in general, quick starts don't affect range that much, but a couple considerations:

    1) If you're in a steady cycle of stop/go (between traffic lights for example), accelerating faster will have you at a higher speed sooner and thus higher average speed over that distance. That will have a direct energy cost to overcome wind resistance.

    2) Braking recovers only to the system limitations on regeneration -- if you brake too late/hard and the friction brakes are used, that energy is lost. Decelerating with paddles will ensure only regen is used, but is limited. Watching the power bar while braking you can see where regeneration is occurring in the green. The brake controller blends in friction brakes to make the feel seamless (better than any other hybrid I've driven) so you can't tell for sure, but in general if you see the meter moving more in the green as you press harder you're using mostly regeneration.

    To your other questions -- the heater is a pure resistive element, and is pretty costly to run (unless the ICE is running anyway, in which case you do get free heat from the engine). To maintain a given temperature, there probably isn't any benefit in manually cycling it vs letting the thermostat do so, but not using heat at all (temperature "Lo", Climate button/screen AC "off") is best whenever you can stand that. Using AC in hot weather isn't nearly as costly as heat. And in both cases, trade off the desire to optimize range with the willingness to be comfortable in your nice car!

    I can't comment on car washes -- I rarely do that so when I do run through a car wash I need real contact with brushes thwapping against the surface to get all the dirt off; I avoid touchless ones :)
    DrDeke likes this.
  20. jdonalds

    jdonalds Well-Known Member


    Our weather has been into the 80s and 90s until a couple of days ago when it dropped into the 60s. On shorter trips when we know we're not going to run out of juice we just drive and use the cabin heater, while still in EV only. Since last Saturday our EV Range estimate has dropped from 49-50 to 46. So the heater certainly does suck up the power.
  21. palmtreeinadumpster

    palmtreeinadumpster New Member

    I don't believe that the Clarity has a traditional heater core. I think that heat is always pure electric. When in HV mode the engine revs much higher when you crank up the heat.
  22. Dislin

    Dislin Member

    Thanks all, pretty great responses in here!

    Yeah, mine started out with poor guess-o-meter EV range (high 30s) after ~50 miles of test drives, so I'm trying to slowly improve that and try to determine my actual range, which is kinda difficult since I've been barely driving so far.
  23. Carbon_Negative

    Carbon_Negative New Member

    I read most of the comments and scanned through the rest and reflect on a few of them. First my own experience:
    I typically read and memorize the estimated electric range prior to driving away and leave the GPS set to "Home". This allows me to easily compare the reported change in EV range with the actual miles driven. When I know that that I will make it back home all electric I don't care how I drive and typically accelerate faster. The power use indicator has 8 segments of which the last two have the white sector. I try to prevent pushing the pedal that deep, in part because that often results in a ICE start which then runs for one or more minutes. I try to keep the accelerator below the 4/8 mark where possible.
    There is a cluster of retail outlets close to Lidl we frequently drive to. The GPS distance is 3.5 miles or 7.0 miles round trip. Half the distance can be driven at 50 mph, but there is a section with a max speed of 35 mph and 4 stop signs. When driving normally, accelerating up 35 mph followed by gentile stops, the electric range reduces by about 12 miles. When I drive the same round trip accelerating very slow (well within 3/8 of scale) and coasting to a stop using only the paddles, the electric range reduction is about 5 miles. The way we drive the car our electric range is both indicated and checked to correspond to 49 to 55 miles (average about 52 miles).
    I did multiple test over longer distances (over the same ~ 25 miles section of coastal level road) on a semi-highway driving 55 mph. Including the section to reach the semi-highway, the GPS distance traveled is typically about the same as the reduction in electric range. Often I notice I can speed up to 60 mph and keep the ratio of miles driven to miles "used" at 1 to 1.
    When I know I can make it home without ICE, I drive fully electric even if this includes sections where everybody (including me) drives 70 to 75 mph. When I know that I cannot make it back home fully electric, my rule is to switch to hybrid mode once the car speed is higher than 55 mph. On the home bound trip I do the same, but switch to electric only one the GPS tells me I can reach home electrically for the remaining distance. In my case that is typically a 9 mile GPS distance over secondary roads, for which I know I can do it using ~ 6 miles of range (due to lower driving speed).

    The electric range indicated is a prediction based on energy used over distance travelled (personal driving styles and local conditions, mountainous versus flat terrain). Driving most of the trip at speeds of 70 mph in hybrid mode does not appear to affect the predicted electric range. As far as I can figure it out, the Clarity records the electric miles history separately from the hybrid miles history. The miles range electric prediction is a function of the acceleration and speeds when driving electric. Energy losses due to air friction increase with the square of the car speed. When driving to the local mall and back all electric with speeds up to 75 mph, the indicated electric range drops to the 40 to 45 range immediately after the next full charge. It appears to take 5 to 10 full battery charges and use of moderate acceleration and speeds below 55 mph to reach a new "steady state" in indicated electrical range after trips using higher speeds or higher acceleration.

    In general the electrical resistance is a function of temperature. For metals the resistance is lower at lower temperatures, but for electrolytes, the resistance increases with lower temperatures. That is the most important reason why pure electric cars have about 2/3 of their range under cold winter conditions. The latter is the case since the electrolyte (in the Li-Ion battery) transfers electrons in chemical reactions which run faster at higher temperatures. So there is an optimum condition to be reached. I am sure Honda engineers tried to optimize the wiring. Reports from people who took Tesla's apart indicate that the primary cables between battery and motors were very thick. This is likely similar for the Clarity, but since the motor capacity is much smaller there are likely thinner cable used. For the same power draw the Clarity would have higher cable power losses than a Tesla. At typical power draw (say 50%) and component temperatures of between 30 and 100 degree F, power loss for electric cars are dominated by battery losses at low temperature and wiring losses at high temperatures.
    To reach the "ludicrous" mode, Tesla heats the batteries while driving (using electrical energy), since this will reduce battery resistance and allows to withdraw more Amps from the same battery, allowing "ludicrous" acceleration.

    A good thing about the Clarity is that when driven in hybrid mode, the battery is kept at optimum temperature by the heat dissipated from the ICE. When alternating hybrid mode (at high speeds) with pure electric mode (in slow traffic) the battery temperature under cold weather conditions can be maintained for a long time close to its optimum with minimum increase of battery resistance and minimum reduction of electric range.

    Heat transferred to air within the car is mostly ventilated (if not recycled) or lost trough window glass. Direct heat transmitted to the body is only transferred to the car interior via the body (breathing and skin). Hence while the sensation of heat through the seats entering the body makes you feel warm, the amount of energy lost to the environment outside the car is much smaller. Using the seat warmers is therefore more efficient for the same level of comfort.

    Summarizing, slow acceleration and deceleration will always result in a longer range due to lower electrical losses and the prevention of activating the brakes. This is aggravated at lower winter temperatures when parked outside and driving purely electric. Driving at lower speeds also reduces air friction. Based on tables published for the Tesla's, the optimum speed is about 30 mph; driving slower than 30 mph thus reduces the electric range. Maintaining speed at a constant 55 to 60 mph on flat roads results in a 50 mile electric range for our Clarity.
    This all applies to a 1.5 year old Clarity with 17,000 miles of which 3/4 driven electric. I am not sure how the battery will hold up over time, especially since it is not easy to limit charging to 80% of capacity (as recommended by Tesla), while operating the battery between 20 and 80% would seriously limit the electric range.

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