how to drive the car

Discussion in 'Clarity' started by victor_2019, Jul 29, 2019.

  1. KentuckyKen

    KentuckyKen Well-Known Member

    Must be something wonderfully wrong with my Clarity. It has never reved up the engine to anything unpleasant or even overly noticeable; not in steep hills in HV and not even in town after using up all the EV range and auto entering HV. (But I’ve only tried that last one once.)
     
  2. neal adkins

    neal adkins Active Member

    One thing worth mentioning is depending on type of driving it may be fine to use all the ev range. I was a 180 miles from home and in stop and go traffic when I was a little concerned that i had used all my ev range. The ice was revving more than usual. No worries though. I just used hv charge for a few minutes and got a couple more bars. Nice to have a different options.
     
  3. 2002

    2002 Well-Known Member

    Some people have reported that on long trips their EV range declines somewhat even though they are in HV mode. This makes me think that HV mode is less aggressive trying to maintain SOC when there is EV range left. HV mode uses electric power as needed but waits for an efficient time to recharge the battery to its previous level. If you have EV range it might wait longer since it knows it has plenty to spare, but then it can sometimes get too far behind to catch up without essentially going in charge mode, and so it just allows the EV range to remain a little lower. However when you have 0 EV range then the battery is down to the last 10% or so of SOC and so it will be more aggressive recharging, sometimes having to recharge at less than ideal moments which is when you would likely hear the engine being somewhat louder than normal.

    I think that's probably the main reason why most people prefer to keep some EV range, whether or not it actually has any impact on efficiency. Another reason is that you can't run remote climate if you have low or zero EV range and are not plugged in.
     
    neal adkins likes this.
  4. insightman

    insightman Well-Known Member

    I was one of the people who complained about HV not maintaining EV range, but our Clarity has somehow learned how to do it. Our EV range didn't decrease at all on some legs and no more than 2 miles on any leg of our 243-mile (mostly 60-70 mph) trip this weekend. The EV range did decrease a couple of miles between legs, however. I believe this is what people on this forum have called an HV "reset." We started with 51 miles of EV range and had 40 before I turned off HV 20 miles from home (I forgot to cancel it earlier). Because I usually hog the Clarity, my wife drove the whole way--she enjoys the 60 extra HP available in HV.
     
  5. jdonalds

    jdonalds Well-Known Member

    This makes sense to me. If you have some EV power available the car will use a mix of EV and engine generated power to drive the wheels. If you have insufficient EV power the engine has to do all the work, and even give some up to charge the battery.
     
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  6. 2002

    2002 Well-Known Member

    Actually for the most part HV mode works the same regardless of whether you have EV range or not. HV mode by definition is "charge sustaining mode", meaning it will try and maintain whatever the SOC was when it entered HV mode, and that's true whether the driver pushes the HV button with plenty of EV range remaining or in "forced" HV mode when EV reach 0 at about 10% SOC. In either situation the use of electricity depends on where SOC is at the moment in regards to the current SOC target. Having available EV range should in theory not affect the decisions that the computer is making since it still has the same goal of trying to maintain the set SOC.

    One visual difference that might throw some people is that if you are in HV mode with available EV miles you can observe the EV range going up and down. However in forced HV mode at 0 EV miles it stops displaying the normal up and down changes in SOC even though they are still taking place. During that time you can only observe the SOC changes either with something connected to OBD2 or by using the app, of course for safety only checking the app when stopped.

    That being said as we were discussing some people have observed that when SOC is higher, HV mode doesn't always seem to "charge sustain" as strictly as it does at low SOC especially at the 10% 0 EV range level. But this effect is rather slight and seems to be noticed only on longer trips where the loss of EV range accumulates enough to notice.
     
  7. ClarityBill

    ClarityBill Active Member

    I think the algorithm is the same with bars, or zero EV. I have attached two graphs, one is at zero EV range, the other with 50% battery. The similarity is astounding to me. Both seem to keep the battery in a range of about 8%.

    It is very disappointing the system does not take advantage of the additional battery available, to keep the ICE in lower RPM range. I believe the Atkinson mode is not used at high RPM, so the ICE is actually less efficient.

    These are not the same road, and HV mode is a longer drive... but I hope you will notice the similarities.
     

    Attached Files:

    craze1cars likes this.
  8. craze1cars

    craze1cars Well-Known Member

    ClarityBill, Nice to see the graphs illustrating what I have felt in thousands of miles of driving this car far beyond its short EV range. I have long been swimming against the stream of people on this site who continue to insist that preserving a certain amount of EV range is necessary for various reasons such as maintaining hill climb acceleration power, or in order to avoid angry bees and make the car more pleasant to drive at lower rpms, or whatever perceived benefits...

    I simply disagree.

    I believe any perceived benefit to be a placebo effect. People HATE seeing a low battery on anything and just can’t stand it, even if it’s harmless, so those who preserve some charge during a long drive genuinely believe it provides a benefit. And I have disagreed with most on his site for nearly a year now on this topic, after experimenting repeatedly on drives lasting hundreds, and sometimes thousands, of miles. I’m past 20k now, with probably 2/3 of miles in HV as we do many long road trips.

    I have always found it makes absolutely no difference whether someone manually switches to HV early, or whether someone just lets the battery go down to 2 bars and allows the computer to decide when to turn HV on automatically. I have driven thousands of miles thru mountainous and high-load interstate conditions using both driving methods to reach my conclusion. I simply never had the means to make comparison graphs like that to illustrate my conclusion for others...
     
    Last edited: Aug 6, 2019
    TJT likes this.
  9. My problem is that I attempt to use the Regen Paddles on my non-EV cars to slow.

    It doesn't work. :-(
     
    rickyrsx likes this.
  10. I'm sorry. I'm thick and don't see what you are talking about. You'll have to explain the similarities.

    What do you mean by "Both seem to keep the battery in a range of about 8%"?
     
  11. neal adkins

    neal adkins Active Member

    Nice! I try ti keep an open mind. My questiin would be- since the clutch is not direct drive i wonder if the actual acceleration is deminished (when the ev range is zero) even though the rpm is simular. It doesnt make since to me that the 4k pound car could perform the same with no ev range/power with a depleted battery, especially off the line. But it probably depends on type of driving (cruising/stop n go).
     
  12. 2002

    2002 Well-Known Member

    But it's not depleted, it has typically at least 8% SOC or more and can do the exact same thing it can do at 50% SOC. And of course really even 0% is not depleted, but we assume that is a hard stop that the computer will not go below so for practical purposes we can say that at 0% there no power left. But it never gets there because in HV mode you are by definition in "charge sustaining mode" where the goal is to maintain a set SOC. In the case of 0 EV range the set point is about 10%. Anytime it drops below that some of the generated power will go to recharging the battery. It will attempt to do that with low RPM but as you get farther below 10% it will use higher RPM in order to more quickly recharge the battery and avoid getting too far below the set point.

    Now replace 10% in the above sentences with 50%, and there is no difference. When SOC falls slightly below 50% you experience low RPM, farther below 50% there is higher RPM.

    Now what about when you are at the set point? Personally I think this is when it especially prefers to use direct drive as that is almost certainly the most efficient. It seems illogical that using gas to generate electricity to then drive an electric motor to drive the wheels is more efficient than simply using gas to directly drive the wheels. However being essentially one gear ratio, direct drive is only efficient within a limited power band and it won't be long before it needs to use electricity to supplement the power, so it has to either generate electricity to provide this (higher RPMs) or use previously stored electricity (RPM stays the same). In the later situation using stored electricity can only be done temporarily, if the power demand continues and SOC continues to drop then it will have to start generating electricity to maintain the set SOC target, so again higher RPMs, depending on how far below the set point you are.

    Again the above algorithm is the same at 10% and 50%

    What about above the set point? My personal opinion/guess is that it only goes above the set point through regeneration. Otherwise it would be wasteful to use gasoline to go above the set point, which would essentially be running charge mode. I have used charge mode exactly once just out of curiosity that it actually does function, which it does, but not seeing a need to throw money away I never use it. Now when you do go above the set SOC then like any hybrid it wants to use up that excess charge which it does, in fact it will at times even shut off ICE and go into EV mode (you can see this on the display if you are watching for it) and it will then burn off the extra SOC until it gets to the set point then ICE comes back on as it returns to HV mode.

    The reason regular hybrids always burn off excess SOC is to leave room for regeneration. A PHEV has plenty of room for regeneration (except when you are fully charged) however you want to leave room for later charging which presumably is cheaper or is at least better for the environment, so it's better to use extra SOC to power the car prior to arriving home. Of course the computer has no idea when you will arrive home so it immediately burns off the excess SOC.
     
    Last edited: Aug 6, 2019
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  13. craze1cars

    craze1cars Well-Known Member

    Well explained, 2002. Your first sentence in particular is what I believe people tend to not realize or fully understand. Even when this car goes down to 2 bars on the battery gauge and forces itself into HV mode, there is still always enough reserve power remaining in the battery to get it up the next steep mountain pass, or to maintain 80 mph on cruise control indefinitely. I have done it many times and can confirm this in the real world. So many seem to have this belief that it is not capable of doing this. And then most admit, after writing this, to having never actually tried it! Or maybe they tried it once when car was new before the car had any time-built logic accumulated. Most of us by now realize the car tends to “learn” some things with time (range estimates for example), especially those who have done the 12v battery replacement and started the learning process over with the hard reboot/battery disconnect thing. My car revved more unpredictability off the dealer lot for the first 1k or so, than it does now that it’s settled in. Seems accumulated logic tamed it down early in life and it’s extremely predictable now.

    Anyway now with 20k on the odometer I have tried it many many times in all sorts of circumstances. Just let the battery run “dead” and keep driving after the engine fires up. The car operates no different at a low SOC, than if I were to manually turn HV on at any other random higher SOC. The engine/generator will simply rev fast enough and often enough to maintain and restore that charge set point as needed....whether that set point is user selected manually by pressing HV button SOC of 80%, 50%, or a computer forced 10ish%

    I also agree with you on charge mode. Total waste that I honestly feel should never be used. I likewise tried mine once just to confirm it works. Have found no practical reason to ever use that mode again.

    AND your speculation about going above the set point is spot on. It only does it with regeneration, not with the engine. Coming down long mountain passes I have seen the car go from about 25% on the battery meter (where it was set once for me when driving up a big mountain pass in HV mode that I manually turned on) clear up to about 70%, by paddle driving all the way down the mountain. I believe it could have gone higher but I was at the bottom so I don’t know. But it went WAY beyond the set point. But the ICE was off the entire descent. It’s one of the reasons this car gets INCREDIBLE mpg when driving in HV through mountainous terrain...because it stores lots of gravity for later use. I feel this an ideal mountain car for saving gas, even for someone off-grid who doesn’t use the plug-in feature.
     
    Last edited: Aug 6, 2019
  14. craze1cars

    craze1cars Well-Known Member

    Simple experiment any doubter can easily try.

    Full charge, find a safe place, cram right foot to floor and hold it there and clock yourself zero to 80.

    Repeat sometime at 50% charge.

    Repeat another time with depleted battery in forced EV mode.

    Compare results. Spoiler: I’ve done this. There will be no appreciable difference in times. Just margin of error likely from running the stopwatch and/or wind speed, as my numbers on all 3 tests were within 1/2 second.
     
  15. ClarityBill

    ClarityBill Active Member

    The 8% range means if you start at 50% the system will operate between 50% and 42% (50-8=42). If you start at 11% (Zero EV range), the system will operate between 11% and 3% (11-8=3) and get similar ICE operation.

    In the 8% range, the ICE will throttle up and down to keep the battery charged.

    Even at 42% charge remaining, the ICE will go to high rpm to try and maintain the charge. The misconception is the system would allow the car to use more battery, and not work the engine so hard.

    It will stay in gear mode in a 5% range (in both situations).
     
    Last edited: Aug 6, 2019
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  16. ClarityBill

    ClarityBill Active Member

    One reason that I still put my Clarity in HV mode early: I use an HV reset to keep the RPM down, and this is not possible with zero EV remaining. This is only important for long hills, or with the heater running.

    I am able to keep the RPM below 3,000 - even up to 80 mph, on 'all' roads.
     
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  17. 2002

    2002 Well-Known Member

    Not sure what is meant by HV reset, I'm guessing this means using charge mode to increase the EV range, then turning off HV then turning it back on again to reset the target SOC to the new higher value?

    For hill climbing if you experience that you have lower RPM's on a long hill climb with EV miles than with 0 EV miles, then you should also see the EV range drop quite a bit during the hill climb, more than it normally would in HV mode. Is that what you are seeing? The problem in comparing the two scenarios is, at least for someone without access to RPM and SOC data, is that at 0 EV range the display no longer shows you any changes to SOC like it does when you are above 0 EV range, so it all becomes subjective based on our eardrums, and we have people saying that they get lower RPM's with EV range than without, then some say later they can't duplicate it, and others don't experience any difference. I think actually tracking like you are doing by more people in repeatable driving scenarios is the only way to prove things.

    The theory would be that in certain driving conditions the system is less aggressive in maintaining SOC when you have EV range, meaning that in some situations it will "borrow" more power from the battery than it normally would since it knows that it is in no danger of getting near 0%. Whereas at say 10% SOC and you are in a sustained hill climb, it will only borrow the normal few percent and after that ICE is on its own.

    This could also explain the anecdotal EV "leakage" as I call it that some people report in HV mode on a long drive, where EV range slowly goes down. A similar theory might explain that, with plenty of EV range the HV system sometimes borrows more than normal, which it intends to pay back, but if it never finds enough efficient moments to pay back the borrowed SOC then it eventually just resets itself to the new lower level. But that is just a guess of an explanation for a phenomenon that again is more anecdotal than documented.

    And on top of that we believe that at least in the past some people experienced a software glitch when SOC was at 10% or below which caused the system to unnecessarily panic and go into angry bees mode, or even worse a limp mode where it only allowed enough traction power to move off the highway with all the rest of the high powered revving going towards charging. Both of those problems however appear to have been solved through software updates as we no longer hear about them, but the residual effect is that because of those past reports people still worry about running out of EV range.

    I don't discount out of hand anything anyone experiences, the question is whether a particular phenomenon is an anomaly experienced occasionally by some, or how the car normally works. So far I think it points towards the former not the later in most cases, but it could also be that there are some subtle things about the car that we haven't fully understood yet.
     
  18. craze1cars

    craze1cars Well-Known Member

    If lower rpms are the goal and drives are relatively short, it works fine. But with the understanding that each HV reset loses a few miles of EV range. So if you take a 400 mile driving trip and try that for every hill along the way, I’m quite certain at some point you’ll eventually be out of EV range entirely, and end up being forced to let the car do what it does anyway. But if you reach your plug in destination before then, it works. Length of drive and terrain will make a big difference in how this works.

    I am also of the opinion that some high RPM blasts under load are very healthy for engines, so I’ve never had the goal of keeping rpms down. So I’m letting the engine sing when it feels the urge to do so. But I will confirm that your method can work fine for those who are adverse to periodic high rpms, and l have played with that periodically myself.
     
  19. ClarityBill

    ClarityBill Active Member

    Nope. No HV charge mode.

    HV reset means just pushing the HV mode button twice. When the ICE is getting ready to rev due to lost charge, doing the HV reset gives it a new target, and it will not rev up.
     
  20. 2002

    2002 Well-Known Member

    Got it. Some people switch to EV as a way to avoid high rev's climbing a hill, hoping to gain it back through regen on the way down, although of course it doesn't always work out that way. And also EV will get used up pretty quickly depending on the speed while climbing the hill, in essence merely postponing the inevitable. Whereas using HV during the hill climb won't of course be perfectly silent but usually not too bad, and it can maintain that for much longer. As SOC drops and it does begin to get a little noisy some people are perfectly fine with that, but I can see how HV reset can be used as a way to minimize the noise. Although at some point as craze1cars mentioned you might wind up using up all of your EV range and not be able to silently cruise the streets of Telluride or wherever.
     

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