My Clarity really annoyed me yesterday!

I don't think it's a case of HV reset causing EDM to be engaged outside of its normal range of operation. In fact it's being used as a method to bring engine power into that range. According to the owner's manual:

"When the vehicle is driving under light load within a certain speed range, the engine provides direct power to the wheels."

When battery charge is significantly below the set point in HV mode, the engine will be using a lot of torque to recharge the battery in addition to what it is already using to propel the car. The theory seems to be that in some cases this additional power requirement is what is putting the torque out of range for EDM. By using HV reset to lower the set point in that situation, this causes the torque to drop into range and EDM is engaged.

I suppose the opposite could be true in some cases and using HV reset could cause it to drop out of EDM, but I am guessing that as long as the gear icon is displayed most people won't be pressing any buttons.

 

I don’t think the Honda programming for HV hold is designed for cold, hills and speed.

I’m a new owner. But I’ve found that in hilly areas it better to select HV charge on downhill side. If i know the downstream elevation changes I will continue to charge if it’s level or down grade mostly. This keeps the ICE from cycling on and off as well as trying like heck to maintain the Hold setting.

If I know the road ahead is a few miles of hills, I’ll let the EV mode power me up the incline. Then on the downside back to HV hold or Charge.

I wish the car had a 4th setting. “MPG max”. Let the ICE come on and stay on while operating at 1800-2000rpms in a load range that nets 60mpg. Allowing battery to fluctuate with a larger range 3-25 mile range. If it gets down to 5 miles EV range a driver notification is sent to change to hv hold or hv charge.

 

I have thought the same thing about a fourth mode but for another reason. The reason that most of us don't like driving in HV mode around town or in hills is because the system is fighting so hard to keep the battery from losing too much charge, which makes for a sometimes annoying amount of noise or lack of power. The only remedy being to switch to EV mode, but then we will use up our EV miles at a fast pace, which in some cases we are trying to preserve. This type of noisy and quirky behavior is understandable in a regular hybrid because they have a very small battery, and it's not good to let it get too low, so they do what they have to do to keep the charge within a certain range. Then again we are basically in the same situation in our cars if we get to 0 EV miles, in which case this type of behavior is understandable because again there aren't really any other options.

But a PHEV has a much bigger battery, and most of the time plenty of battery charge. If we know that our total trip will be within our EV range, then sure we are going to drive in EV mode the whole way. But in cases where we will be driving farther than that, we normally want to decide which portions will be EV and which HV. But that's our only two choices, EV and HV (HV+ typically coming into play later if EV range is getting low). EV mode burns up our range too fast, but HV mode has all of its annoyances. I think a fourth mode would be very useful, maybe simply called PHEV mode, since it's a mode that would be unique to PHEV's. As with regular HV mode it will use the gas engine for primary propulsion and battery power as a supplement, but in PHEV mode it would not try and maintain a particular SOC. It would limit RPM's when accelerating to what is more typical for a standard gas powered car, perhaps even quieter, and use battery charge for the rest of the power needed. Same thing when climbing a hill, try and keep RPM's to what most people are used to on that particular grade, and use battery charge to make up the difference. It would still charge the battery when it can, but only when it can do so without limiting power or making a noticeable amount of additional noise, that will normally be when the car is cruising at a steady speed. But also keep the charge rate low enough to not take the car out of direct drive mode if possible.

This would give a PHEV the unique ability to operate very similar to a gas car in terms of performance and noise, unlike a regular hybrid which requires acceptance of quirky behavior for the "greater good" of better gas mileage. Most of us find HV mode annoying to some degree, some more than others, but we are willing to accept it. But I think there is a larger segment of the population that might warm up more to the idea of a hybrid vehicle if they knew that there is a "higher class" of hybrid vehicle available that drives and sounds like a normal car (even better in some cases), and won't act weird at times or embarrass them in front of their friends. And also be capable of pure EV driving at times, something that a regular hybrid can't do except at low speeds for short distances. And of course have a major impact on gasoline usage, much more than a regular hybrid.

Of course in some scenarios driving in PHEV mode the range will eventually start to get low, and require switching to HV mode to avoid reaching 0 miles, or perhaps some may choose HV+ in some situations. Rather than a notification (which us geeks would like), I think for the general public it would be better if it automatically switches from PHEV mode to regular HV mode at a predetermined EV range. Perhaps that could be customizable in the settings, along with an option for a notification instead of automatically switching modes for those who prefer that. And I think it should still start each trip in EV mode as a default like our cars currently do.

So the three standard driving modes (again HV+ having a different purpose) would be EV, PHEV, and HV modes, since the car can operate in all three, unlike any other type of car. I think that would be pretty cool and add one more advantage to PHEV's.

 

Try driving in sport mode, you will feel all sound but also all the power.

 

I just wanted to add my two cents about engine rev noise. I think someone mentioned it is a relative experience. Here is my anecdote.

I drove me and a bunch of friends to a very hilly countryside. We took two cars. My clarity, and a sporty mercedes sedan (forgot which one). Now there are some REALLY steep inclines.. where they have warnings. Now my car in EV mode took them no problem, but my friend commented that it didn't seem like my EV handled them that well. Which is fine, my car did decelerate a bit near the top as I didn't want to push it into HV mode. The next time we took this hill my friend drove in the mercedes behind us. He mentioned that he took it back because the mercedes, trying to keep up with us sounded like it was about to explode trying to get up the hill.

I've experienced this before as well because people really associate engine noise with acceleration so people think the EV is not performing or accelerating that hard when a car next to it has to be in full rev just to try to keep up. You see this with the modded cars that sound like they are reving at super high performance when they are simply accelerating normally, but the people in the car feel like they are out accelerating everyone.

It may have been a simple case of being very used to not having much engine noise to navigate hills then experience what other people would normally experience and finding it out of the ordinary.. especially if you are expecting the same torque performance as in pure EV.

 

The electric heater operates to warm the cabin in cold weather (supplementing engine source heat) as well as warm the engine as it cycles in HV mode.
Some aspects of the design puzzles me, but you can minimize the losses with a winter front and leaving the temp and fan speed as low as tolerable.
Even in the summer, the electric heater will run to get and maintain (if needed) the engine coolant temp in the normal range when in HV mode.

 

That’s a plausible theory. The information from the manual indicates that the engine must be under “light load” and “within a certain speed range” in order for EDM to engage and remain engaged. That is also my experience with EDM.

Without those two conditions being present, no amount of button pushing will engage EDM or allow it to remain engaged. Under heavy load SOC will decline, the engine will rev as designed, and the driver will be in the same situation as they were previously, only now the SOC set point will be lower.

The EDM maneuver is a nifty trick on relatively flat terrain. I’ve been able to get EDM to engage on a fairly consistent basis by lifting off the throttle until the needle dips into regen and the easing back on the throttle. It doesn’t work every time. It could be that the SOC needs to be closer to the set point for my strategy to be successful. Just a guess. That method allows EDM to engage without reducing the SOC set point each time.

In my opinion, forcing EDM when not under light load is futile.

 

If you ever discover a way to recapture all the kinetic energy through regen, or any other method, you will be a very wealthy person.

 

Depending on the length and steepness of the descents, you may want to experiment with recapturing energy while in EV mode. With a cold engine, HV Charge takes a bit of time before it will produce results. It also will not charge if the SOC is above 60%. You may be able to recharge the battery as much, or more than HV Charge, without running the engine.

 

The way that I understand the theory is that the engine would be under light load if it was not working so hard to recharge the battery to the set point. So by doing HV reset and lowering the set point, in that specific situation at least it would "lighten the load" and bring engine power into EDM range. The engine might then be able to maintain charge while staying within EDM range.

I agree though that in some situations you would just be postponing the inevitable, for example if driving on an uphill grade then the SOC would fairly quickly drop down again below the set point and it will have to raise RPM's again and thus drop out of EDM. But I can imagine other situations where the system gets kind of stuck. Say if you had a brief uphill or maybe a passing maneuver that dropped SOC well below the set point, but now you are on more level ground where EDM could in theory be engaged, but now it needs to do quite a bit of charging to recover the large amount of SOC, so EDM is not engaged. And that might last a long time if you still have a slight uphill rise or maybe drag due to high speed. And also maybe be noisy. Whereas using HV reset to lower the set point brings the power back into EDM range, which it can perhaps maintain for quite awhile and still maintain the current SOC.

Of course all of this is just conjecture, it would take a lot of experimentation to prove out any theory. Specifically that more total time is spent in EDM by doing this. But it's theoretically possible at least, so if people say they sometimes find themselves in situations where using HV reset will engage EDM and it can be sustained for some time after that, that's terrific. I'm not sure myself that I would be paying that much attention to it as I am not what I would consider a hypermiler. Hypermiling is great for those who enjoy doing it, I'm just not one of them.

 

It seems the Clarity was just not designed to go up and down hills very nicely. Since I moved from CT to FL flatland both the cruise control and the HV modes work way way better. On the highway it just sits there mile after mile in EDM with only occasional forays into electric drive. I no longer bother to toggle between HV Charge and EV in around town gas engine use because HV is just fine now.

The cruise contol on highways holds speeds +/- 1 mph no problem instead of +/- 4 with high revving to catch up when it falls behind. And of course electricity is much cheaper here so I maximize EV mode.

I assume since this model is built in Japan that it was tested mainly in Japan, anyone know what the terrain is like around their Japanese R&D center?

 

its made near Tokyo (Sayama, Japan) but they have big area of national parks with hills nearby
https://goo.gl/maps/ntcary3WjA1v73wF9

 

Well, same commute and during winter months, I often don't have enough battery so the last few miles on the way to work, it ends up running on ICE. This is on the way to work, since I charge there for free.

Basically, 50-60 on a US route with the last 7 miles without traffic lights. Then jump onto an interstate for about 3 miles, and then exit and 35mph for a 1/2 mile.

ICE would kick in before I get on the interstate. But a few days ago (with temps in the high 20s), ICE kicked in right when entering the interstate. Engine warmed up and car technically kept on consuming battery. But the Guess-o-meter might have not been accurate, and as soon as I got on the exit ramp, the angry bees came out in full swing. Car kept going like that for the last 1/2 mile and noticed I was down to 1 bar.

I think winter time and the guess-o-meter being odd did not allow the car to warm up in time before the battery got really low.