All of us are speculating. You are correct that the engineers went out of their way to make the car "comfortable" for people who have been driving traditional gasoline-powered cars for decades. IMHO some of it was well done - the regenerative brakes, for example, mimic traditional brakes to an amazing degree - and some of it is silly, like the car creeping forward. But angry bees are not comfortable. It would seem much more comfortable to pick a non-obtrusive rpm level that is also reasonably efficient and run the engine at that level when it's running. Yes, it will seem strange to people at first when there is no linkage between their pressure on the accelerator and the speed of the engine. But it's a lot less strange than angry bees!
And it may not be reasonably possible. If engine to generator coupling is direct drive, as I speculate...adding gearing would add cost, weight, complexity, and friction, and take up precious under hood space which might not fit it. And the engine itself might not have enough torque to turn a steeper gear ratio at lower rpm while the generator is under a big load...and now we need a bigger engine... Lots to consider. And maybe too many tradeoffs....
These two diagrams I found (one from Paul Tan's website and the other from Honda's i-MMD video) indicate that the starter motor/generator is not inline with the engine's crankshaft (left image), but permanently connected to the crankshaft through gears that step up the crankshaft's speed (right image).
“Irate bees begging for bloody mercy”... @craze1cars, you are now in my pantheon of Clarity heroes. (That ones right up there with @insightman ‘s “premature enginualtion” to describe Bob’s excessive ICE operation) And BTW, nice explanation.
As long as we've gone so deep in the weeds here...lets go deeper LOL. More hillbilly VERY ROUNDED math from me...since I can't find any specs for the power output of the Clarity generator. (does anyone know? I'd LOVE to know...) I charge my car from "dead" to "full" at about 7,000 watts in a bit over 2 hours. If I take my car out on the interstate at 75 mph in EV mode I can drain all those little elecrical nuggets I crammed into the battery and force the car into HV mode in about 35 minutes. Rough estimate means in order to maintain that speed under that load, the battery needs to generate nearly 4 times the output of my charger to keep the car moving forward indefinitely (which it is capable of doing as I proved in my 4,200 mile road trip). So 7,000 watts x 4 = a generator under the hood of this car that is likely capable of pushing out 28,000 watts. Now lets go shopping for a 28,000 watt generator.....here's a nice 25,000 watt unit from Generac: https://images.homedepot-static.com/catalog/pdfImages/60/602cbaaf-0633-44a9-b654-271439f2d03d.pdf Well would you lookie at that spec sheet?!! What a coincidence! This generator is produced with a 1.5L naturally aspirated engine (sound familiar?..I actually chuckled when I saw that) And it also spins at 3,600 rpms to make its power.... Granted it's an LP/NG machine, not gasoline...but power outputs aren't that much different with fuel types. This speaks volumes to me. Here we have a car with a 1.5L engine under the hood, and I'm pretty sure the generator on board needs to generate more than 25,000 watts in HV Mode at times of heavy load, like long high speed interstate runs. So there is no question in my mind that this engine NEEDS to spin 3,500 rpm or more consistently, to maintain that over the long term, like on road trips. Which is about what my car sounded like it was spinning all the way across the state of Nebraska. And in HV mode just buzzing around town it also OCCASIONALLY needs to spin that fast to do simple things like accelerate from stop lights, climb hills, and keep us warm with that wasteful electric resistance heater. Because humans aren't used to their little engine needing to work that hard? They complain about angry bees when the Honda computer summons them to work... My comparison here might be largely irrelevant, but physics are physics -- whether gears exist or not, if they gear it too steeply, a little 1.5L engine simply won't be able to turn the force required to generate the electricity needed...it would simply require a bigger engine. See how when you step up to the 36,000 watt Generac, it is built with a 2.4L engine? This Clarity engine NEEDS to spin like the wind...to slow it down would require larger displacement...
The generator analogy is absolute brilliance. So simple, even Thag, the cave man (meaning me), can understand it. I have now added you to the hallowed halls of the Clarity Brain Trust. Membership card and secret handshake info will follow.
I like your logic. What you are saying is that the only way that this small engine can produce enough power to turn the generator aggressively enough is by running at very high rpm. Enter angry bees. Or at least annoyed bees. But this logic suggests that the engine should be running that fast in HV mode to provide enough power (via the generator) to speed the car down the road at highway speeds. And in my experience, it doesn't.
Mine certainly has sometimes, not always. With a headwind and cruise control set at about 78 or 79 mph? Heading toward the Rocky mountains and slowly gaining elevation? My engine was racing pretty good...little doubt in my mind it was at 3,500 or so for hours on end. And my fuel economy was down to close to 30 mpg during that run. Now normally if I tame it down to 65 mph with no wind or light wind? It sounds to my ear like my engine maintains a very reasonable 2,200 to 2,500 and I typically can get 40+ mpg on that type of road trip. Highway speeds are different for different people and different circumstances, and at higher speeds wind resistance becomes an exponential equation...5 mph difference can sometimes cause a 20% loss of efficiency/need for 20% more power. Wind is huge. Wife and I have driven our Clarity over 10,000 miles so far (only 4 months of ownership!) And more than half of those miles are in HV mode as we do many 300 mile round-trippers to a rapidly aging parent that needs our help, plus the big 12? State road excursion. It varies quite a bit how the car responds, and varying conditions change things rather noticeably. I now look for American flags to see which way the wind is blowing and how strong it's blowing on these trips -- and I can semi-accurately predict what a flag is going to look like before I see it, based on how the engine is revving down the interstate. And MAYBE -- maybe it's geared somehow and the generator runs a different rpm than the engine. I don't know...
Has your Clarity had the service campaign updates and, in particular, the software update (18-089 or 18-090) for the EVTC (update PGM-FI software)? LeoP
I am awed by your engineering insight. But at least I am enough of a trivia master to know what a "pantheon" is! (Yes, I am a font of useless knowledge.)
1 horsepower is 746 watts. 28,000 watts is less than 38 hp. The ICE we have is able to produce more than 100hp, even with losses. Calculations based on steady-state highway driving are good for that particular situation. The generator can provide this kind of power at reasonable RPMs. I do encounter high RPMs when going up a steep hill on a deleted battery. In my case, the engine starts at low RPM and the energy flow display shows that both the engine and the battery provide power at first. After a short while, the engine increases RPMs and starts not only to propel the car but charge the battery a little, to restore whatever energy was used from the lowest SoC it tolerates.
In cases where the "angry bees" are obtrusively loud (but without noticeable loss of power), is it possible that the active noise cancelling is not functioning properly or optimally? I wonder if there is a way to measure the ANC by tapping into a speaker wire ... or disabling it by a fuse to see if it is any different (worse or better). I am not sure if a malfunctioning or poorly tuned ANC could amplify the noise rather than cancelling it out. Just thinking out loud...
craze1cars I'll join the list of folks who say "kudos"...great write up and analogy. Easily understood to even us hillbilly's...lol I will use your post when others are asking for an explanation and ensure you get the props. The fun part is...I have a 17kw Generac sitting next to my house and it never occurred to me to draw a parallel. That is why I read forums like this...everyone can always learn something. With that said...Generac recommended maintenance for general conditions for the 17 kw machine is: - every two years or 200 hours of operation. That is oil and filter change. Generac defines severe conditions as Cold weather below 40f/4.4c or hot conditions 89f/29.4c Generac recommended maintenance for severe conditions for the 17 kw machine is: - every twelve months or 100 hours of operation. That is oil and filter change. I look at this info in context of not only your post but also @leop where he references engine revs and working harder etc. Link to thread is: https://insideevsforum.com/community/index.php?threads/a01-advice.4191/#post-42478 As a side note...Generac also recommends a weekly 15 minute exercise cycle which is programmed as a default when it is installed. Sound familiar? Good info from both and thought others might appreciate the Generac specs as additional information. Good post and good read. Have a good day.
Just to add a bit for my situation: I've never, not even once, flipped to EV or for that matter HV to try and second guess the car's algorithm, or defeat it. My car cannot run quietly even on flat ground unless it has EV charge remaining (period). 5-days a week, my commute totals 20 miles. Lucky me, even my 26 mile EV range does this without needing to burn gas. I go home at night each night, plugin and can go a week or two at a time on electric only. So I just drive the car most days in its default mode (EV). I also have *never* hit the detent on the accelerator, doing slow starts, and using paddles for regeneration daily. I don't run the cabin heater at all, save to defrost windows as needed, and I turn off when I can. So I'm very careful because my EV range is limited (more so than others on this forum). On weekends I do some trips, and sometimes a few hundred miles -- including on flat ground. Even if I am religious about hitting HV when I hit the freeway, I will exhaust my EV range. It's not occasional, it's guaranteed and predictable. My car *never* preserves EV range in HV mode, it just starts ticking down as I drive down the road. I then use long-press HV button to get some EV range back, but not to run in EV mode, just to augment HV mode-- the car is much quieter in HV mode when there is a non-zero amount of EV range. I *do* get advertised MPG. I also never lose power. I can accelerate without issues. I simply dislike the sound of high RPM, and find doing my best to preserve a non-zero EV range seems to keep the car driving more quietly. But I'm not pressing buttons back and forth to force modes. I press HV and leave it in HV on all long trips to preserve EV range. Even so, EV range is *always* exhausted. So by the way, I realize my experience isn't that common. I get past the angry bees sound by playing the radio while I drive. -Dan BTW: even though my experience may not be as good as others, I love the car. Also, i used to drive a 4 cyl subaru outback 2003. It was a gutless wonder. In short, the Honda has more power than I'm used to.
Great discussion generated by Craze1cars! While I agree that we should relax more about the "angry bees" given that the program would never allow the engine to exceed the red line, I still advocate keeping a significant charge when driving in HV during road trips. My Clarity has never revved high if I kept a significant charge, even on mountain upgrades. When HP is needed the energy flow diagram shows power coming from both ICE and battery. When my battery was low, not even depleted, the ICE raced loudly on a nearby mountain upgrade while I was going only 45 mph behind the big semi trucks. The flow diagram showed that all the power came from the ICE and nothing from the battery. With a significant charge, I race up the left lane going 65 mph with the ICE humming quietly and the flow diagram showing power coming from both ICE and battery. That's obviously how the car wants to run because it could otherwise rev the ICE highly if that's more efficient. At the top of the hill, when the road flattens out and descends, the ICE continues to run to recharge the battery (I'm in HV mode). Honda installed 2.0 litre engines in the much lighter Accord and CR-V hybrids. These cars use the same i-MMD drive system as the Clarity. Even with the more powerful ICE, combined peak horsepower is the same as the Clarity (the hybrids have smaller traction batteries), which means in the Clarity the battery plays a much bigger role in providing peak horsepower than the ICE. The Clarity should be able to provide some battery power when "depleted" at two bars but the program seems to avoid that in favor revving the ICE highly. I much prefer getting plenty of power with my ICE humming quietly than to have it screaming on a depleted battery.
I will comment this seems incorrect...as though something is wrong with your particular car. If I press HV mode when I have 3/4 battery, I can and have driven 600 miles starting with about 3/4 battery, and by the time the trip is over I will still have 2/3 battery. It MIGHT drop a bar or two at the most, and that's it. Next day I go 600 more miles on starting with that 2/3 battery, and it might drop to 1/2 battery. I have never used HV Charge mode as I see it as rather senseless. If the battery dies down on a trip, I just drive it in HV until I can plug it in again, but never go to HV Charge as that will just make the engine burn extra fuel and spin faster to charge the battery for no good reason. But I experienced on my 2 week, 4,200 mile road trip, that my car would take thousands of miles to exhaust down to nothing, without any charging, if I just leave it in HV mode. In fact just yesterday I did 150 mile round trip on it. I hit the HV mode button with about 1/2 battery, and by the time I got within 20 miles of back home I left it in EV mode after a gas stop, and it still had about 1/2 battery to get me the last 20 miles back home....
I think we need to consider what effect altitude has on the power the engine can produce. I live at about 5000 feet. Last late spring I took a trip from Salt Lake City to Las Vegas. The outside temperature was in the high 60s so I turned the climate control off for the entire trip. I traveled 2 miles to the freeway and put the car into HV mode and immediately set HV mode after fuel stops. My EV mileage was at 64 at the start of the trip and once it dropped below 40, I got the angry-bee (I would guess 5000 plus rpm.) which lasted for about 70% of the trip. Over the 800 mile trip I was unable to plug the car in. As I traveled, the EV mileage would slowly decrease. I returned home with 17 miles of EV left. During the trip, the only time the angry-bee would go away was after traveling several miles down a long hill and occasionally if the hill was long enough, the clutch would engage. Most of the trip was at 75 or 80 mph. Higher altitudes significantly reduce the power an engine can produce. A 1500 cc engine cannot generate enough power to propel a 4000 pound car at higher altitudes.
@craze1cars, while I like your basic philosophy of letting the car do what the designers intended, there seem to be multiple credible accounts of unexpected (and dangerous) behavior where the vehicle just can't maintain 'highway speed' - described as can't get above maybe 40 mph even with the angry bees in full swarm. I don't believe these people are randomly pushing buttons causing computer algorithms to go awry. The best theory put forth in the forum is that this condition is maybe exacerbated (or can be prevented) by intentionally not allowing battery depletion on 'long' drives. Dan seems to be unlucky enough to have a unique situation where HV is not maintaining SOC as purported (even though he is a 'gentle' driver). My point here is that there may very well be some fringe conditions that were not fully fleshed out during the design process. Hopefully, Honda is paying attention in some way, and can further refine these algorithms. This car is still pretty much a specialty (although similarities exist to the Accord), it is not a high volume production car, and likely never will be. We are very pleased so far, but don't have nearly the driving experience that you do (have had the car for 2 months, only ~1200 miles almost all EV). We have not experienced any such anomalies [yet] (HV seems to hold charge fine, and we have yet to experience the bees). Thanks for sharing your extensive driving experiences.
