I am really hoping someone can analyze the high-rev, power-loss situation. My only experience close to that was pressing the accelerator and getting high-rpm's with no acceleration. I was stunned, but then realized I had more accelerator pedal: Pushed down more, and took off. The quick response of RPM's and engine sound threw off my perception. I am also recording pedal position (but hide it in the posted graphs). Most of my driving is in cruise control, so the pedal position is really boring (zero). There are also load and torque numbers that don't seem to add anything to the discussion (I can't figure out what they are). They are only active when the engine is running, but don't vary much during operation.
ClarityBill: Let me test out a thought on you... Your scenarios with unacceptable noise are almost exclusively at 73 MPH. I think it is pretty clear that 70+ MPH is definitely pushing the little ICE, and it will need to have high rev's particularly if there is hill involved (and especilly in HV_Charge like your one experiment). I have not been on a trip yet with this car where I had any kind of a sustained run with speeds that high. There is a portion of your "HV Charge" run that is interesting. There are two regions with "flat" speed. The first one, maybe 67 MPH, and the second one at 73 MPH. The RPM's were roughly 3200 for the lower speed stretch and 3500 for the faster one. The RPM's are pretty much tracking the speed (this is not 'direct drive'... Much higher RPM's than direct for these speeds). If you had gone 60 MPH, then the RPM's would have likely dropped even more to 2800 (even lower if it had been HV instead of HV Charge). At some point the noise crosses below the threshold of unacceptable (and/or the gear comes on). Could it be that those who mostly operate below 60 MPH largely avoid the bees and don't experience objectionable noise levels while those who frequently cross 70 MPH have a different experience? Also, as you demonstrated, to whatever extent the gear icon can be active, that noise level will be quite good (73 MPH == 2600 RPM). Undoubtedly there will be some instances at 60 MPH where the bees may need to swarm because of a steep hill, but these occurrences may be much less frequent and shorter duration than they will be at 70+. I'm sure you couldn't do this without causing an accident, but it would be interesting to travel on your long uphill stretch of I88 where you have the loud noise, and do 5 minutes each at 73, 70, 65, 60, 55 to characterize the un-swarming process. Maybe at 2:00 AM, but then a cop may pull you over for going too slow ! I see no reason to believe that your car isn't operating exactly like the engineers designed it. There are clearly pieces of the operating envelope that are more attractive than others, and you are doing us a favor by helping to characterizing this envelope.
Mr Fixit, I can try out the varying speeds, I am sure it will have an impact. But I think the SOC is the more important factor. The first 28 minutes Angry Bees 2 is the same road as the bad section of Bee Control (minutes 26-65). In Angry Bees 2 the rpm's never hit 4K, and there are sections of gear drive. In Bee Control, the rpm's go over 4K, and much of the time is over 3500. The rpm's driving this same section of road, at the same speed, are very different: The cause is the difference in SOC. My theory: The higher SOC requires the generator to run faster to generate the voltage needed for charging. Generator voltage varies with the speed of the generator. When the SOC is lower, the battery is operating at a lower voltage: The generator can get amperage into the battery at a lower voltage, and run slower. Angry Bees 2 shows driving 73 mph with reasonable rpm levels. It goes high for climbing grades, but not excessively. To test out the varying speed vs SOC: I have a 60 mph drive tonight that I would normally just do in EV mode. I can do it in HV and see if the engine has to go high rpm to maintain 80-100% charge in the battery...
ClarityBill: Although you could be onto something regarding SOC, I don't believe that it could have anything to do with "overcoming" the battery voltage to get the desired current. Except at the extremes (near full charge or near zero charge) there is very little change in the battery voltage across a very wide range of SOC. Here is a representative curve to illustrate...
Cold weather will definitely limit the output of the EV battery, particularly when the SoC is low, although the ability to recharge is better at that SoC compared to a higher SoC with the same cold battery. This chart below is taken from a webpage (https://www.gs-yuasa.com/jp/deepstory/vol5.html) (and translated from Japanese) to show performance of what I believe is our Clarity EV battery (EHW5).
I think MrFixit may have something. I think speeds above 70 mph are a significant factor. It seems to me that a number of threads have contained references to unsatisfactory/excessive engine noise at high speed conditions. I rarely go over 70 mph, but my only experience of angry bees was doing 72 mph going up hill in HV with a half full battery, temperature in the high 20Fs. The minute i reduced my speed to 67, the noise stopped even though all the other conditions remained the same.
MrFixit Looks like battery voltage cannot be the basis. But my Clarity sure seems happier with low SOC (not zero) in HV mode. I did a quick run with some 60 mph driving. Not great test, but it did not hit 4K rpm. There were definitely some annoying bees, and the quietness of the slower driving may have made them more noticeable.
I assume you were HV from the start of the run? The vehicle clearly "wants" to shed some charge before stabilizing at ~90%. This seems consistent with not being able to regenerate with too high of an SOC. Something else I find interesting is that your ICE was running virtually the entire time. It mostly cycled between 1500 and 3000, but didn't turn off at all after the 1st 8 minutes. My data is much more limited, but when I was in HV (with zero battery), the ICE cycled on/off a good bit (well, this is only a 5 minute piece, and I was going slower than you):
I was in HV mode before I moved the car, so it was the entire time. My HV mode seems to allow some drop in SOC before maintaining the SOC, even at lower levels. Starting HV with zero battery would not allow that starting drop. Seems like the control is operating in proportional mode, with not enough integral (PID control analogy). Your chart may be just the starting period for me, while it was allowing the battery to lose a little SOC. The non-stop ICE after 8 minutes seemed to be gear drive. I think it would drop to synchronous speed, then increase to recharge battery. I definitely saw the gear during my run... It was a two-lane road, so I wasn't able to watch closely.
You are absolutely right. Honda states in their videos. Just drive like a normal car and let the car decide what is best. No way to avoid the high revs at times. Or, put it into charge mode when the battery is less than 25%.
Driving last night, I hit some hills at 73 mph, after a while, the ICE started to rev, so I switched out of HV mode for less than 3 seconds, and went back into HV mode, and the ICE went back into gear mode to finish the hill. I did not accept the high rpm's that the car thought was best, the SOC charge dropped a little, but the rpm's were comfortable. (I stopped the angry bees from swarming.) It was an extended grade, so I did this 'switch out' twice: About 74 and 76 minutes on the attached OBII graph. (At minute 68, the rpm's came up, but the car got itself back to gear mode). I am looking for ways to improve my comfort driving the car: I don't 'let the car decide what is best.' Maybe Honda will incorporate my operational suggestions into their future models...
Bingo!! The engine in this car is primarily a generator. It does NOT propel the car in most circumstances. As anyone who owns a generator can attest, they FREQUENTLY run at full throttle. So the fact that this car runs it’s engine periodically at higher speeds is fully expected, and very efficient. The fact that people feel the need to somehow trick the car into slowing down the engine just baffles me...do NOT hit the EV button just to shut the engine down! Yes its like a home generator, but usually generators are placed outdoors away from where you can hear their whining. Honda should have given us an easy way to avoid the whining by giving the option to lock the car in gear mode and use whatever battery is needed to supplement. Having to regularly switch from HV to EV to reset and prevent the whining is ridiculous.
I’m not saying the revving engine is quiet and pleasant. I’m just saying it’s part of normal operation in certain circumstances, and fully harmless to the car and the engine. Those who are fully annoyed by it when it happens, certainly won’t be fully pleased with this car. And that’s one primary reason why Consumer Reports disses the car, and I think rightfully so. Anyone who prioritizes silence at all times, but regularly exceeds the EV range of the Clarity and/or does a lot of high load driving at the same time, really should buy a different car. Cuz the engines gonna rev at times and that owner will not be satisfied. But the revving engine doesn’t bother me, nor does it mean the car is defective. It is normal. Those are my primary points.
@ClarityBill: Fundamentally it seemed like you had elected to invoke HV when your SOC had reached ~50%. This is exactly what I would do when on a trip that significantly exceeds EV range in order to retain substantial charge during a 'long' highway stretch. Then, when a charger is within reach (on the way back home for instance) go back to EV and deplete the battery just before reaching home. Each time you exit HV (even only briefly) then return, a new setpoint is established (and it is typically, if not always lower than the prior setpoint). In your case, the two "switch outs" you did resulted in a new SOC setpoint that was closer to 40% than to 50%. You chose to prioritize 'comfort' by trading off SOC in order to maintain lower engine RPM's. I would have prioritized maintaining the desired 50% charge and let the car do what 'it' wanted to do (that is what HV mode does - maintain SOC). The higher rev's are most often pretty short in duration and at 73 MPH, I find the higher rev's are not at all objectionable. The Honda engineers wisely designed this car so you don't need to play around, but you certainly can if you choose to. As such, I would not advocate "incorporating your operational suggestion" at all. The hooks are already there for you to manually intervene, but I can't see changing the default operation based on your preferences.
I’ll post a complete report when we get back home, but yesterday we drove over 800 miles from N GA to S FL. About 80% Interstate with HV selected the entire time. Cruise control often set to 75 mph. Engine noise was never intrusive, and usually completely inaudible. Then again, I’m pretty close to getting fitted for hearing aids, so there’s that!
The car prioritizes efficiency over sound, because they're trying to maximize MPG. It would possible to reduce sound at the expense of energy use. Perhaps that could be in sport mode or some such. On the poll I made almost 70% of people came from a ICE only car, so not being used to a hybrid car that starts the engine when it needs to as a generator may be unexpected.
Bravo!!! You nailed it. Better Efficiency VS. Quieter Ride There is always a sacrifice. Off topic somewhat. I am in the process of adding sound insulation in the hood, doors, trunk, firewall. Budgeting $200 for materials only. If I hear the difference, I will attempt the roof and floor.
There is another alternative--lower speed. I have found that reducing the speed to just below 70 mph seems to asure a quieter ride.
I agree about the speed. Which is why I don't consider the Clarity an ideal highway cruiser for the western US where there are miles and miles of wide open road with high speed limits. Parts of I-15 in UT have an 80mph speed limit, most other non urban parts of I-15 have a 75mph speed limit. Most of that is two lanes and even the semis are pushing that speed limit. Drive much slower than 75 and deal with angry drivers behind you. I tried setting ACC at 80 and it seemed like a little too much, 75 was OK but noisy. When I get out onto the open highway I want to relax, it wasn't a very relaxing ride.
