driving in the mountains - Page 2 - 2018 Honda Clarity Forum
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post #11 of 24 (permalink) Old 09-02-2020, 08:35 PM
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Regenerative braking isn't constrained by this and will fully charge the battery if possible. The car will remain in EV mode until it reaches the HV/Hold SOC point again. As long as the SOC is above the HV/Hold set point the car will operate as an EV. The ICE is still turning via wheel spin; ICE water and oil pumps are pumping to maintain engine temperature and lubrication; and the fuel injectors are turned off.

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If you exceed the target SOC by descending a mountain both the Volt and Clarity will turn the injectors off to the ICE and let the engine continue turning via wheel spin until the battery is depleted back to the target SOC.
I took your previous post to mean that instead of using regen during the downhill to dissipate energy (and increase SOC while doing so) it will instead spin the engine as a way to dissipate energy (and decrease SOC while doing so) as a way to avoid exceeding the target SOC. Apparently I misunderstand what you were saying and I guess you were not talking about while descending the hill, but rather at the end of the descent when you need power again, i.e. level ground or now going uphill. Is that correct?

I agree that when the descent has ended if you are above the target SOC that it will run EV until SOC drops back to the target. That is how all hybrids work, at least the hybrid systems that I have driven which is Toyota and Honda. But even in that case there is no reason for it to spin the cold engine during this time, that creates a drag that the electric motor (which is now powering the wheels) has to overcome with higher battery drain. Keeping the fluids moving when the engine isn't being used doesn't seem necessary, these engines are designed to repeatedly stop and start. Restarting the engine takes a fraction of a second and very little power. True the oil pressure will have dropped and some of the oil will have started draining out of the engine, but it's not like starting a dry, cold engine, the engine will still be quite warm and there will still be some oil in the crankcase and on the metal surfaces. i would just be really surprised that during level driving in HV mode when the engine is shut off that they would use battery power to continuously spin the engine while it is not running. I know you said the wheels are spinning the engine, but again if this is while the electric motor is turning the wheels, then using the wheels to spin the engine will effectively be using the battery. And in the case of Clarity the engine has to be spun by the battery because it is not a powersplit planetary like the Volt, the Clarity engine most of the time is not connected to the wheels, it is only spun by the generator motor. It does go into direct drive via a clutch at a fixed gear ratio but only at steady speeds and only when the engine is running.
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post #12 of 24 (permalink) Old 09-02-2020, 10:51 PM
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Not real clear, was I. The engine is kept spinning to enable significantly faster restart. It's a trick auto makers developed called Deceleration Fuel Cut Off and it keeps the ICE engine turning without burning any fuel. In this mode you can start/stop an ICE engine in roughly every half second. The amount of friction in a modern automotive gas engine is very, very tiny. There's actually an order of magnitude friction from the flex in the tires as they roll. You want to keep the engine warm - it doesn't have to be hot, but anywhere above about 50F will do and the oil and coolant circulating to avoid jarring the engine when the car needs to switch back to gas. If you don't do this you're looking at up to a full minute to restart the ICE engine to avoid excessive stress and wear on the engine.

2018 Honda Clarity Touring PHEV - Forest Green w/Tan interior (wife's car)
2017 Volt LT - Heather Gray; black bow ties, Charcoal VoltShelf
2012 Cruze ECO MT (hail totaled 5/8/17 103,600 miles @42.5 MPG)
2010 Mit Lancer GT MT (traded for ECO @31K miles)
2002 Pont Montana AWD - title to son at college graduation
1990 Pont Transport (traded for Montana @240K miles)
1986 Fiero GT MT (traded for Transport - needed more seats)
1985 Fiero 2M4 MT (traded for Fiero GT @8K miles)
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post #13 of 24 (permalink) Old 09-03-2020, 12:02 AM
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I'm still a bit dubious that an engine is going to cool down that much after the typical thirty seconds or so of EV before it comes back on again, but I guess the engineers know best. On a separate but similar topic, I have often wondered about true cold engine starts in the Clarity, meaning switching to HV when the engine has not run since yesterday (or longer) and is truly cold and dry. From my observation when I press the HV button in that situation while on the freeway for example, the engine starts but it basically just idles for the first minute or so, which agrees with what you are saying at least in a true cold start situation. I'm not basing this on RPM, since RPM doesn't tell you much as far as engine load when the engine is just spinning a generator. Instead what I base my opinion on is watching the EV miles. I notice that when I first switch to HV you see the engine light come on, but the EV miles continue to decrement at the same pace they do when driving EV, even though the EV light is not illuminated. The EV miles continue to decrement at the same pace for about a minute, showing no sign of slowing, then very suddenly they stop decrementing, and then slowly start increasing back up towards the target. So clearly the system is avoiding putting a load on a cold engine until it has warmed up.

It's quite different however if you do pedal to the floor acceleration on a cold engine. I did that as a test and to my surprise the engine roared to life. I have no way to know how much power it was contributing, but based on the noise probably something. It's probably not all that great for the engine to have to provide instantaneous power after being woken up for the first time that day (or week or month) but then again for most people it's very rare that you put the pedal to the floor, so probably the engineers decided that if you do then you probably have a real need for it (avoiding an oncoming train as just one example), so wearing the engine down a little is an accepted tradeoff, if it only occurs infrequently it will have little effect on overall engine life. But I don't recommend someone who is a leadfoot to do this every morning, just like you shouldn't do that with any gasoline engine. Then again people with a lead foot aren't always prone to thinking beyond the moment.
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post #14 of 24 (permalink) Old 09-03-2020, 10:03 AM
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In a separate but similar topic, I have often wondered about true cold engine starts in the Clarity, meaning switching to HV when the engine has not run since yesterday (or longer) and is truly cold and dry. From my observation when I press the HV button in that situation while on the freeway for example, the engine starts but it basically just idles for the first minute or so, which agrees with what you are saying at least in a true cold start situation.
In the Volt you can actually see how much power is being generated by the ICE and the Electric motors. For the first 65 seconds at highway speed the ICE contributes less than 5KW to the powertrain. Definitely nerve racking the first time I saw this at 75 MPH going up a slight hill out of Denver on I-76.

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It's quite different however if you do pedal to the floor acceleration on a cold engine. I did that as a test and to my surprise the engine roared to life. I have no way to know how much power it was contributing, but based on the noise probably something. It's probably not all that great for the engine to have to provide instantaneous power after being woken up for the first time that day (or week or month) but then again for most people it's very rare that you put the pedal to the floor, so probably the engineers decided that if you do then you probably have a real need for it (avoiding an oncoming train as just one example), so wearing the engine down a little is an accepted tradeoff, if it only occurs infrequently it will have little effect on overall engine life. But I don't recommend someone who is a leadfoot to do this every morning, just like you shouldn't do that with any gasoline engine. Then again people with a lead foot aren't always prone to thinking beyond the moment.
I've done the pedal to the metal with a cold ICE in my wife's Clarity and yes, the ICE revs really high, but it provided zero to the car's acceleration. Once the ICE is warm it provides acceleration during these high revs. As for how rare, consider what you have to do when getting on a short uphill freeway on ramp where traffic is moving at 55-70 MPH. You really need to be moving with the flow of traffic when you reach the start of the merge area to give yourself room to adjust. This is a weakness in the Clarity that it requires both the electric and gas motors to get full power.

2018 Honda Clarity Touring PHEV - Forest Green w/Tan interior (wife's car)
2017 Volt LT - Heather Gray; black bow ties, Charcoal VoltShelf
2012 Cruze ECO MT (hail totaled 5/8/17 103,600 miles @42.5 MPG)
2010 Mit Lancer GT MT (traded for ECO @31K miles)
2002 Pont Montana AWD - title to son at college graduation
1990 Pont Transport (traded for Montana @240K miles)
1986 Fiero GT MT (traded for Transport - needed more seats)
1985 Fiero 2M4 MT (traded for Fiero GT @8K miles)
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post #15 of 24 (permalink) Old 09-03-2020, 11:18 AM
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I've done the pedal to the metal with a cold ICE in my wife's Clarity and yes, the ICE revs really high, but it provided zero to the car's acceleration.
I doubt it's zero, unless you are speaking figuratively. If while driving EV I go just past the blue into the gray area, causing ICE to come on, you barely hear the engine and that may be closer to zero, but when you floor it the revs go much higher so it is contributing something, although maybe not as much as if the engine is already somewhat warmed up. Although having a warmed up engine in EV mode is somewhat rare, unless you happened to have just switched from HV to EV a few minutes before the hard acceleration event occurred. When you are driving in EV mode a hard acceleration is generally a one time event caused by some circumstance (short onramp, avoiding a hazard, etc) and it will likely not be repeated for the rest of the drive time that you are in EV mode, so the now warmed up engine is unlikely to be called upon during that particular drive. That's why I am skeptical of the common belief that while driving in EV mode you have this great surge of power just waiting to be called on by pressing the pedal past the detent. But since in almost cases the engine will be cold, I think it's unlikely to contribute all that much power. But since the Clarity lacks the Volt's power gauges, the only way to really know how much additional power that you get from a cold engine is to hook up a dymo, or do several 0-60 tests both warm and cold. But they need to be controlled repeated tests, i.e. exact same section of road, driving conditions, etc. and do multiple identical 0-60 runs then average them together as well as throw out any outliers. It's something I have been meaning to do, but whereas it's easy to do multiple warm engine 0-60 runs, cold engine is much harder because you can only do one, then the engine warms up and that's it for that day, you have to wait another day to do another cold engine test.


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As for how rare, consider what you have to do when getting on a short uphill freeway on ramp where traffic is moving at 55-70 MPH. You really need to be moving with the flow of traffic when you reach the start of the merge area to give yourself room to adjust. This is a weakness in the Clarity that it requires both the electric and gas motors to get full power.
For most people I think that is rare. Most people don't have freeway onramps that require literally putting the pedal to the floor in order to be at traffic speed when you merge. Someone who has on onramp like that which they use every morning when going to work, sure for that person it is not rare. But for most people I think having to press the pedal to the floor is rare, not a daily or even weekly occurrence.

Well there is a type of person who it is not rare for, the type of person who shoots out in split-second gaps in traffic in front of other cars and then has to put the pedal to the floor to avoid impeding the car that they just pulled in front of. But that is not safe driving, so I don't consider that as a normal situation that most people encounter on a regular basis. I really think that for the vast majority of people and the roads that they drive on, pedal to the floor is usually only needed when the driver has made an error in judgment and they need massive acceleration to get out of the situation. I can think of very few cases where putting yourself in a situation that requires having to press the pedal to the floor would be considered part of safe driving. To me it's like ABS, it's there if you need it but if you are using ABS every day then something about your driving habits is wrong. Again someone may live somewhere with specific unique driving situations that absolutely require pedal to the floor on a regular basis, but that would be an exception, and even then I question whether it's really required or they just are too impatient to wait for a safe gap, or they don't want to turn right instead as that will take longer, so it becomes an excuse "I have to jump out there or I will be there all day". Sort of like people who claim you have to drive over the speed limit on the freeway "or you will get run over". That's just an excuse. It is quite easy to safely drive the speed limit even when other traffic is going faster, you just stay as far to the right as possible and maintain a steady speed. People get on your bumper even then, but that's not because they couldn't slow down in time it's because they want to intimidate you into speeding up because their offramp is coming up and you are in their way. I normally use cruise control on the freeway and I just let them sit and fume and they usually either back off or go around me.
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post #16 of 24 (permalink) Old 09-03-2020, 12:52 PM
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Figurately, but it definitely not what the Clarity's ICE provides when warmed up already.

I've driven all over the country and have found that really old on-ramps and newer on-ramps are decent. It's the on-ramps that were built during the double nickel (55 National MPH) era (1972 - late 90s) that are way too short for today's highway speeds and also on-ramps in dense urban areas. There are a lot of these on-ramps.

Passing on two lane roads, especially in mountains, is also best done pedal to the floor. You want to accelerate hard and complete the pass and then get back in your lane. This has the additional side effect of discouraging the driver you're passing from accelerating with you because they aren't paying attention to their speed.

2018 Honda Clarity Touring PHEV - Forest Green w/Tan interior (wife's car)
2017 Volt LT - Heather Gray; black bow ties, Charcoal VoltShelf
2012 Cruze ECO MT (hail totaled 5/8/17 103,600 miles @42.5 MPG)
2010 Mit Lancer GT MT (traded for ECO @31K miles)
2002 Pont Montana AWD - title to son at college graduation
1990 Pont Transport (traded for Montana @240K miles)
1986 Fiero GT MT (traded for Transport - needed more seats)
1985 Fiero 2M4 MT (traded for Fiero GT @8K miles)
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post #17 of 24 (permalink) Old 09-03-2020, 06:16 PM
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Figurately, but it definitely not what the Clarity's ICE provides when warmed up already.

I've driven all over the country and have found that really old on-ramps and newer on-ramps are decent. It's the on-ramps that were built during the double nickel (55 National MPH) era (1972 - late 90s) that are way too short for today's highway speeds and also on-ramps in dense urban areas. There are a lot of these on-ramps.

Passing on two lane roads, especially in mountains, is also best done pedal to the floor. You want to accelerate hard and complete the pass and then get back in your lane. This has the additional side effect of discouraging the driver you're passing from accelerating with you because they aren't paying attention to their speed.
As for passing, I am sure there are a lot of opinions on that, but personally I only pass when I have enough passing distance that I can safely accomplish the pass by going the speed limit or slightly higher. If it would required pedal to the floor that either means the distance that I have available to pass isn't enough, or else the person ahead of me is not that far below the speed limit, in which case I just stay behind them and I don't pass. Even if you wind up being stuck behind them for several miles it doesn't affect the driving schedule as much as people think it does. At highway speeds if the car ahead is going within 10 mph of the speed that you want to go it, it only adds about three minutes for every 20 miles of driving. And in many cases you won't be stuck behind them even that long.

I realize there is the concept of reducing the amount of time spent passing the other car, with the belief being that this is safer by reducing the exposure. But assuming you have enough passing distance and there are no oncoming cars close enough to be an issue (which there shouldn't be if you are passing safely) the only risk is from the other car if they swerve into your lane, which is highly unlikely if there are no upcoming drives or roads that they might turn left into. Putting the pedal to the floor and passing at 20 mph over the speed limit on a two lane highway is not safe in my opinion. As for the driver speeding up to keep you from passing, well that's just like if someone cuts in front of you on the freeway leaving a gap of ten feet, instinct and emotion leads us to want to stand our ground and not slow down, but that's not safe. When someone cuts in front of me, I slow down to a safe distance. My health (and life) is worth much more to me than my pride. That reminds me of another one of the "excuses" people have. They say they can't leave a safe gap with the car ahead of them on the freeway because if they do someone will just take advantage of that and cut in front of them. And I ask is your point that it is unsafe or it just annoys you? Yes for the few seconds it takes for you to slow down and increase the gap you are potentially at higher risk, but is the solution to constantly drive at higher risk by not leaving a safe gap?
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post #18 of 24 (permalink) Old 09-04-2020, 09:58 AM
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I agree there are different opinions on passing, but here're my thoughts:

- I was taught in drivers' ed to accelerate and get back into my lane as quickly as possible. This doesn't always require full throttle acceleration but on occasion it does, especially on twisty mountain roads where passing zones are infrequent and relatively short. Don't start the pass if there's any risk of completing it.

- Put your car on cruise control (used to ensure a steady speed) at 1 or 2 MPH faster than another car on the interstate. About two thirds of the drivers you pass will accelerate to match your speed because they have no clue how fast they're going and unconsciously accelerate because they see you in their peripheral vision. Once you pass them they slow back down. I've noticed that about a quarter of the drivers will accelerate as much as 5 MPH, and a few even more, when you do this unless you accelerate during the pass. Invariably these drivers actually slow down to below the speed they were doing before you passed them - another sure sign they had no clue as to how fast they're actually going. More proof that most drivers have no clue to their speed - I was on cruise control at 75 MPH (posted speed limit) near Burlington, Colorado about 15 years ago. There was a long line of traffic (turns out it was close to a quarter mile of cars) doing just under the speed limit in the right lane and no one in the left lane. No indications of construction on a bright sunny day with dry roads and no wind. I pulled into the left lane and remained at 75 MPH. As I reached the head of the line there was a Colorado State Patrol cruiser running just under the posted speed limit. Not a single one of those drivers behind him knew how fast they were going and/or what the road's posted speed limit was.

- I drive in an environment where the average passing zone is about a half mile. When you commit to a pass you really need to commit to completing it quickly, leading to harder accelerations at the start of the pass. In addition I generally don't start the pass from right behind the other vehicle either, preferring to stay back a ways for better visibility of the road ahead of them. This also leads to harder accelerations during the pass to ensure it's safely completed. I've found Sport mode in the Clarity to be the only operating mode that really allows for this. When I drive on open, flat roads, I don't need to accelerate or if I do, it's not a full out acceleration.

2018 Honda Clarity Touring PHEV - Forest Green w/Tan interior (wife's car)
2017 Volt LT - Heather Gray; black bow ties, Charcoal VoltShelf
2012 Cruze ECO MT (hail totaled 5/8/17 103,600 miles @42.5 MPG)
2010 Mit Lancer GT MT (traded for ECO @31K miles)
2002 Pont Montana AWD - title to son at college graduation
1990 Pont Transport (traded for Montana @240K miles)
1986 Fiero GT MT (traded for Transport - needed more seats)
1985 Fiero 2M4 MT (traded for Fiero GT @8K miles)
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post #19 of 24 (permalink) Old 09-04-2020, 12:59 PM
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As an experiment, next time you are at a stoplight and there is someone next to you, when the light turns green don't go just sit there. It's surprising how many people won't go until the car next to them goes. Of course you should only do this when no one is behind you. Probably in some cases they weren't looking at the light, but it happens too often for that to be the only explanation.

One time I was on the freeway and traffic was heavy but moving at good speed, but then I came up on a mass of cars in all lanes that were going under the speed limit. Hard to see from that far back but there was what looked like a police car in the front row with lights on the roof, lane number three out of five lanes. Occasionally a car in the fast lane would slowly move up to the front, but once they were there they would shoot off at least 10 mph over the speed limit which I thought was strange. So I got in the fast lane and waited my turn to get up to the front, sure enough it was just a security car, the driver oblivious to the traffic jam he was creating.
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post #20 of 24 (permalink) Old 09-05-2020, 04:51 PM
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As an experiment, next time you are at a stoplight and there is someone next to you, when the light turns green don't go just sit there. It's surprising how many people won't go until the car next to them goes. Of course you should only do this when no one is behind you. Probably in some cases they weren't looking at the light, but it happens too often for that to be the only explanation.

One time I was on the freeway and traffic was heavy but moving at good speed, but then I came up on a mass of cars in all lanes that were going under the speed limit. Hard to see from that far back but there was what looked like a police car in the front row with lights on the roof, lane number three out of five lanes. Occasionally a car in the fast lane would slowly move up to the front, but once they were there they would shoot off at least 10 mph over the speed limit which I thought was strange. So I got in the fast lane and waited my turn to get up to the front, sure enough it was just a security car, the driver oblivious to the traffic jam he was creating.
I've done both of these - this is so common it's proof that most people shouldn't be driving simply because they're not paying attention.

2018 Honda Clarity Touring PHEV - Forest Green w/Tan interior (wife's car)
2017 Volt LT - Heather Gray; black bow ties, Charcoal VoltShelf
2012 Cruze ECO MT (hail totaled 5/8/17 103,600 miles @42.5 MPG)
2010 Mit Lancer GT MT (traded for ECO @31K miles)
2002 Pont Montana AWD - title to son at college graduation
1990 Pont Transport (traded for Montana @240K miles)
1986 Fiero GT MT (traded for Transport - needed more seats)
1985 Fiero 2M4 MT (traded for Fiero GT @8K miles)
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