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David Towle said:
That's my guess too. With the tall gearing the engine is likely way below its hp peak at normal highway speeds. I would offer to try cruising route 9 at 100 mph and see if it stays in engine drive mode more, my guess is it would, but that road is always crawling with police ;).
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I think this is slightly misleading by Honda. Considering when needed; say on a mountain pass or merging, the car can only provide 181hp and possibly less than 200lb-ft torque once battery is drained. Given the electric version is rated 221lb-ft torque for ~4050 pounds car, it is definitely way quicker.
 
Wow...more comments on my question concern then I had hoped. So folks say the gear symbol won't be displayed much while in HV engine mode especially up hill? My simple mind says that's when the gear symboil should come up...so maybe I started thread for nothing since icon won't come on during up hill runs. I did notice the gear symbol come on running backroads when car switched to engine mode after electric miles zeroed.

Thanks to everybody for thier time. Much information on here now.

Edd
 
insightman said:
HV Mode works together with ECON Mode, NORMAL Mode, or SPORT Mode. I believe HV stands for Hybrid Vehicle, but cannot document that belief. Honda's non-plug-in hybrid vehicles work to maintain a charge in the battery so that battery power is always available to provide extra power for acceleration or hill-climbing.

The Clarity is much more pleasant to drive when there is a decent charge in the battery because the car weighs 4,059 lbs and the engine maxes out at a paltry 103 horsepower. Without battery power, the Clarity cannot accelerate or climb hills easily, hence HV Mode is there to preserve battery power for tasks such as driving on the expressway, when higher aerodynamic forces will drain the battery more quickly.

When you switch the Clarity to HV Mode, regardless of which of the other 3 modes is in effect, the Intelligent Multi-Mode Drive (i-MMD) system will try to maintain the battery at its current state of charge (SOC) and use the internal combustion engine (ICE) to power the car and recharge the battery as necessary. When you select HV Mode, you're indicating you want to switch from primarily battery-powered travel to primarily ICE-powered travel.

However, HV Mode doesn't use the ICE all the time. It picks from any of the three basic "drive modes," according to which it decides is the most efficient at any given moment.

The three basic drive modes are EV drive mode, HV drive mode, and Engine drive mode. You don't get to select these modes, the i-MMD system does that. EV drive mode is when the battery and traction motor are powering the car. HV drive mode is when the battery and the ICE-powered starter motor/generator combine to feed electricity to the traction motor. Engine drive mode is when the gear icon appears to indicate the i-MMD system has engaged the Engine-drive clutch so that the ICE is mechanically connected through gears to drive the front wheels. It turns out that this direct connection is the most efficient method of powering the car in some instances, such as when the load is light at expressway speeds.

Only in Engine drive mode is the speed of the engine proportional to the road speed. In other modes the i-MMD system runs the engine at whatever speed it deems necessary to charge the battery and respond to the accelerator pedal. When the battery charge is depleted, people on this forum report hearing the engine revs go uncomfortably high, which they call the "angry bees."

In my experience with HV Mode, the i-MMD system doesn't manage to maintain the original SOC on long drives. The number of bars in the battery charge gauge decreases, which I find disappointing. I believe the i-MMD system should burn as much gasoline as necessary after each acceleration or hill-climb to bring the SOC back to what it was when I pressed the HV button. Rather than burn gas unnecessarily, Honda's engineers count on regenerative braking opportunities to restore the battery's SOC to its original level. That may work when coming down a long hill, but it never seems to work for me.

HV Charge Mode is the least-efficient way to drive a Clarity PHEV because it runs the engine at high RPMs to propel the car and recharge the battery at the same time. It's main purpose is to get a charge back into the battery before the next mountain if you just used up most of the charge on the previous mountain. Honda decided to limit HV Charge Mode to charging the battery to 58% of full charge. When the battery reaches 58% of full charge, HV Charge Mode switches to HV Mode.
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insightman

Great read. I embedded a link in a post on clarityforum.com to this thread and your explanation in particular.

I gave you props up front in the thread https://www.clarityforum.com/forum/1485-post1.html

I didn't think you would mind since proper credit is given.

Thanks
 
Clarity_Newbie said:
insightman

Great read. I embedded a link in a post on clarityforum.com to this thread and your explanation in particular.

I gave you props up front in the thread https://www.clarityforum.com/forum/1485-post1.html

I didn't think you would mind since proper credit is given.

Thanks
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I'm not looking for props, just the dissemination of good information (and hope people will correct me when I'm wrong), but I thank you for your compliment and am happy of others find what I write interesting and beneficial.
 
Thanks for all the input. After watching the computer screen closely when I put Clarity into HV engine mode I do see the gear icon come on but not as often as used to or so I think.

People on here say high revs uphill is okay so I will not take to the service man since the Clarity runs great according to me.

Thanks.

Edd
 
After reading this thread yesterday, I drove 200+ miles in heavy rain and wind between San Antonio and Houston. In previous trips along this route, I seem to remember that engine drive mode, gear icon, engaging most of the time while in HV mode.

Yesterday, while paying close attention, I only saw the gear icon 5-10% of the time. I'm surmising that the rain and wind created enough added resistance to push the i-MMD calculations outside the ideal range for engine drive mode even though I was travelling at 60-75 mph. I'll pay close attention tomorrow when I return tomorrow when there is no rain predicted.

I've always noticed that when in HV mode, the gear icon appears when I'm above 50-55 mph. I was surprised yesterday when it engaged so little during my drive. I did notice the high revs from the engine which was somewhat disturbing so I ended up driving slower (65-70) than I my normal 75 mph to keep the "Angry Bees" at bay. I started the trip with a full battery and only engaged it when I was within EV range of my destination.
 
I did a highway drive yesterday, 30 miles hills then 30 miles mostly flat, then the reverse home. Battery at about 60% average. Each time I started the hill area it would go into gear mode for about a mile, then give up and I never saw the gear icon again until on the flat. And it took about 5 miles of flat driving after the hills before the car would engage gear mode (the car seems to have a memory). On the return trip, starting out on the flat, it went into gear mode right away and stayed in it continuously until a mile into the hills. It was light traffic and I could go a steady speed (well as steady a speed as this primitive cruise control can do) throughout.
 
I've decided the right way to drive this car, especially in the winter, is simply EV in town and HV on the highway. I can stand the lack of heat so far for short trips and that keeps my EV range near 50 local miles. An EV range of near 30 on the highway, even without heat, just makes no sense (both economic and heat wise) to utilize. I normally drive around 72-75 on the highway, if I went 60 the decision might be different.
 
David Towle said:
On the return trip, starting out on the flat, it went into gear mode right away and stayed in it continuously until a mile into the hills. It was light traffic and I could go a steady speed (well as steady a speed as this primitive cruise control can do) throughout.
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Maybe the car's definition of "flat" is very literal. My experience is that anything other than completely flat pops it out of gear mode. When I drive through what I would categorize as "rolling hills" I seldom see the gear icon. Maybe I underestimate the effort to propel the car up these tiny rises, but I'm surprised that it's not more efficient to leave the direct drive engaged and supplement as needed with a nudge from the EV, then replenish part of it on the corresponding downhill. This would slowly discharge the battery but I'd rather have that than the high revs I sometimes hear.

I like options. I would love to have more control over the tradeoffs of robbing from the battery to reduce engine noise. I suspect that the engineers could have done that, but that the marketing folks were afraid that it would make the car look complicated and scare away potential buyers. Maybe I am giving too much credit to the marketing folks; they seem to be almost non existent for this car.
 
insightman said:
The engineers might have worried that giving you more control could have threatened battery longevity.
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Perhaps. But given the number of times that the flow reverses to/from the battery with the current design, that seems unlikely. But we're actually speculating on something that we don't really understand. I think the engineers (in consultation with the product-design team) did a good job. I'm just a geek who would like more levers that I can move.
 
insightman said:
HV Mode works together with ECON Mode, NORMAL Mode, or SPORT Mode. I believe HV stands for Hybrid Vehicle, but cannot document that belief. Honda's non-plug-in hybrid vehicles work to maintain a charge in the battery so that battery power is always available to provide extra power for acceleration or hill-climbing.

The Clarity is much more pleasant to drive when there is a decent charge in the battery because the car weighs 4,059 lbs and the engine maxes out at a paltry 103 horsepower. Without battery power, the Clarity cannot accelerate or climb hills easily, hence HV Mode is there to preserve battery power for tasks such as driving on the expressway, when higher aerodynamic forces will drain the battery more quickly.

When you switch the Clarity to HV Mode, regardless of which of the other 3 modes is in effect, the Intelligent Multi-Mode Drive (i-MMD) system will try to maintain the battery at its current state of charge (SOC) and use the internal combustion engine (ICE) to power the car and recharge the battery as necessary. When you select HV Mode, you're indicating you want to switch from primarily battery-powered travel to primarily ICE-powered travel.

However, HV Mode doesn't use the ICE all the time. It picks from any of the three basic "drive modes," according to which it decides is the most efficient at any given moment.

The three basic drive modes are EV drive mode, HV drive mode, and Engine drive mode. You don't get to select these modes, the i-MMD system does that. EV drive mode is when the battery and traction motor are powering the car. HV drive mode is when the battery and the ICE-powered starter motor/generator combine to feed electricity to the traction motor. Engine drive mode is when the gear icon appears to indicate the i-MMD system has engaged the Engine-drive clutch so that the ICE is mechanically connected through gears to drive the front wheels. It turns out that this direct connection is the most efficient method of powering the car in some instances, such as when the load is light at expressway speeds.

Only in Engine drive mode is the speed of the engine proportional to the road speed. In other modes the i-MMD system runs the engine at whatever speed it deems necessary to charge the battery and respond to the accelerator pedal. When the battery charge is depleted, people on this forum report hearing the engine revs go uncomfortably high, which they call the "angry bees."

In my experience with HV Mode, the i-MMD system doesn't manage to maintain the original SOC on long drives. The number of bars in the battery charge gauge decreases, which I find disappointing. I believe the i-MMD system should burn as much gasoline as necessary after each acceleration or hill-climb to bring the SOC back to what it was when I pressed the HV button. Rather than burn gas unnecessarily, Honda's engineers count on regenerative braking opportunities to restore the battery's SOC to its original level. That may work when coming down a long hill, but it never seems to work for me.

HV Charge Mode is the least-efficient way to drive a Clarity PHEV because it runs the engine at high RPMs to propel the car and recharge the battery at the same time. It's main purpose is to get a charge back into the battery before the next mountain if you just used up most of the charge on the previous mountain. Honda decided to limit HV Charge Mode to charging the battery to 58% of full charge. When the battery reaches 58% of full charge, HV Charge Mode switches to HV Mode.
Click to expand...

This is a great description of Clarity driving modes! Thanks. I've been looking for the gear icon indicating engine drive mode for the last month or so (since reading about it here) but I have yet to see it. I use HV mode fairly often on the highway (when going farther than EV range to next charge) and, for me, HV mode seems to keep the battery charge level constant. I wonder if both of these features of my experience differ from yours because of lack of hills/climbs on my usual highway routes... I need to go for a ride in the mountains to find out.
 
MikeB said:
This is a great description of Clarity driving modes! Thanks. I've been looking for the gear icon indicating engine drive mode for the last month or so (since reading about it here) but I have yet to see it. I use HV mode fairly often on the highway (when going farther than EV range to next charge) and, for me, HV mode seems to keep the battery charge level constant. I wonder if both of these features of my experience differ from yours because of lack of hills/climbs on my usual highway routes... I need to go for a ride in the mountains to find out.
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For me on flat/gently sloping highways the gear icon is on 90% of the time. In the hills I never see the gear icon. That you are not seeing it on flat highways seems strange.
My battery level also stays relatively constant in HV.
 
David Towle said:
For me on flat/gently sloping highways the gear icon is on 90% of the time. In the hills I never see the gear icon. That you are not seeing it on flat highways seems strange.
My battery level also stays relatively constant in HV.
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Does your Clarity have the SB Campaign updates s released in October?

LeoP
 
I assumed so but good question not sure how to translate the invoice. Was in on Oct 19 and the software they did was campaign 18-090 PGM-FI software update. Is that the right one?
 
David Towle said:
I assumed so but good question not sure how to translate the invoice. Was in on Oct 19 and the software they did was campaign 18-090 PGM-FI software update. Is that the right one?
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Yes, that is the update that may be causing the reduction in the gear icon being displayed for some. However, the Clarity also appears to learn from the driving history to adapt the behavior of the pcm (powertrain control module). We have not driven much on a faster highway in HV mode since the update. After a while, we may see the previous, before update, behavior return. The update did seem to reset all the pcm parameters to the default.

As a side note. The SB (at least the ones printed out by my Honda dealer and the ones posted in this forum) that speaks to the evtc/3-way valve update is 18-089. SB 18-090 speaks to the replacement of the climate control unit. Our repair/update invoice also has the SB numbers interchanged and describes 18-090 as the so called pgm-fi update. This is just another little Honda mystery.

LeoP
 
My big want for the Clarity (which will never happen)

I drive the same commute every day, and it's longer than 47 miles so I need both electric and gas. I don't pay for my charge, so I'd love to have a commute that minimizes the distance on gas. Since it's every day, I'd love to be able to automate it instead of having to remember when to switch modes. Even better, I'd love to have a learning mode where I could just do the drive and the car would learn my routine and optimize for me.

Ideally, you'd give it your KWH and Price/Gallon, and it could adjust to minimize total cost. Seems like an optimization problem that wouldn't be particularly hard with the right data. Perhaps use traffic data to modify it on the fly, and know when climbs are coming up (keep some battery) or descents (keep some free space on the battery).

Eventually we'll all be EV I guess, but for PHEV to appeal to a mass audience, I think removing the requirement that we manage modes manually would be a step in increasing mass appeal.
 
leop said:
Does your Clarity have the SB Campaign updates s released in October?

LeoP
Click to expand...
I'm going to have to pay closer attention to the display to get better data on if and when I get engine drive mode. But I have watched for it on flat highway that I drive fairly often and haven't seen it. Maybe need to really punch the "gas pedal" and see what that does. I have not had any SB updates - taking it in for first service later this week (after 9 months and 7k miles with the car).
 
Honda salespeople are already over their heads trying to describe what the Clarity PHEV can do. Trying to comprehend and describe features like maximum charge limitation and programmed mode switching would blow their minds.

If only Honda wasn't worried about giving away corporate secrets and potential damage to the battery, it would be great if they would release a software development kit (SDK) for the Clarity PHEV. Then 3rd-party developers could create apps that do what everyone wants.

The app I long for would implement a maximum-data screen. It would not only show what's going on in the Clarity's brain, it would also have optional (and clever) audio alerts for things like ICE operation, brake-caliper activation Engine Drive (gear-icon) operation, and the curious full-battery engine start-up phenomenon (premature enginulation).
 
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