Another theory for HV-charge vs HV

[ClarityBill]

1800-3500 rpms under moderate to heavy loads achieve the best efficiency.
High rpm’s above 5000 is when timing is adjusted back to favor power over efficiency. I don’t think clarity’s ice ever goes there. It’s a dedicated aktinkin cycle. Not a cheater one with infinite valve adjustment and a perpendicular crank.. Although I believe the clarity ice does benefit from some valve adjustment.
I read a good article on this a while ago. I’ll look for one.


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My Ford Van keeps the rpm's in the range of 1800-3500: and it does not need hybrid drive. That does not seem to be much of an advantage.

I have OBDII records of hitting 5420 rpm on a hill climb in the Clarity.

 

[ClarityBill]

1800-3500 rpms under moderate to heavy loads achieve the best efficiency.
High rpm’s above 5000 is when timing is adjusted back to favor power over efficiency. I don’t think clarity’s ice ever goes there. It’s a dedicated aktinkin cycle. Not a cheater one with infinite valve adjustment and a perpendicular crank.. Although I believe the clarity ice does benefit from some valve adjustment.
I read a good article on this a while ago. I’ll look for one.


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It looks like Clarity stays in Atkinson mode for ‘all’ driving, after the warmup is complete at 1500 rpm. I was at 4400 RPM during a hill climb, and the I-VTEC stayed engaged. There were minor changes to valve timing, that were relatively linear to the engine RPM.

I used the AutoEnginuity OBDII system to monitor Atkinson activation.

I found several parameters that seem to reference the Variable Valve Timing system (VTEC). I logged all of these for my first run, but they seemed to follow the first parameter, so I only logged the indicator command and VTC angle for subsequent runs.

I-VTEC Indicator Command (Bit) [0 - 1]
Rocker Arm Oil Control Solenoid Bank 1 (Bit) [0 - 1]
Rocker Arm Oil Control Solenoid Bank 2 (Bit) [0 - 1]
Solenoid Return Signal (Bit) [0 - 1]
VTEC Oil Pressure Monitor Switch Input (Bit) [0 - 1]
VTEC Pressure Switch Bank 1 (Bit) [0 - 1]
VTEC Pressure Switch Bank 2 (Bit) [0 - 1]
VTEC Solenoid - Commanded (Bit) [0 - 1]
VTC System Control (Bit) [0 - 1]
VTC Advance Angle - Commanded (Deg) [-20.0 - 107.5]
VTEC Changes To Hi V / T (Bit) [0 - 1]

When the engine first starts, it stays at 1500 rpm during the warmup phase. The VTEC is not engaged during this time.

VTEC is disengaged anytime the engine shuts off (while in HV mode), but is reactivated when the engine starts again.

I was disappointed the engine did not leave Atkinson mode for the hill climb. The engine was over 4000 RPM, and obviously working hard.

The articles I read show the Clarity has a two-intake cam system. One is Atkinson, and the other is standard 4-stroke. The valve selection is with oil pressure solenoids. The parameters available in OBDII seem to confirm this design.

 

[Clarity_Newbie]

This makes no sense that engagement is predictable based on speed/rpm thresholds unless you're only considering summer perfect weather data. How can I drive for hours in the winter between 65 and 70 mph on rolling highways and the gear mode never engages? There are clearly other factors besides the speed/rpm thresholds that control engagement of gear mode, I think both precipitation (humidity?) and temperature are factors..

David Towle

Data collected on the Clarity I drive indicates it is predictable. Data has been collected and observed through all types of driving conditions and for all intents and purposes...it acts the same. Sure temps/conditions may alter the pattern somewhat but the data curve remains within stated parameters.

My comments are based on data and data only. I report the findings. If the Clarity you drive behaves differently...therein lies the problem...which we are collectively ciphering on.

HagerHedgie

I’m pretty sure it only has to do with the SOC. Your driving style, speed, and the terrain all effect energy consumption. If gear mode can’t keep up with the power you’re asking for, then you won’t see it engage very often.

SoC, whether 30% or 90%, has little bearing on engine clutch engagement for the Clarity I drive. Just last week I drove 150 miles and started with 90% SOC...used EV mode at the destination...and returned home driving 150 miles on SoC 30%...engine clutch engagement occurred as normal though slightly less due to uphill bias on the return trip which is expected.

At the end of the day..."your driving style, speed, and the terrain all effect energy consumption"...which is the root cause of all the consternation over "how" this car operates.

My driving experiences with the Clarity involve typically rolling terrain to mountainous roads. I'm a sedate driver. Driving split 80/20 local/highway. Rarely exceed 65 MPH except on Interstate when 70 mph.

For those who are new to the forum/issue of the "gear icon" below is a link to an earlier thread with relevant info.

https://insideevsforum.com/community/index.php?threads/the-elusive-gear-icon.4112/

 

[Clarity_Newbie]

IMHO, the RPM data is a symptom of gear mode, and not the cause. Gear mode is determined by the SOC.

In HV mode, the ICE will not start until the SOC drops. After the ICE starts, the SOC will continue to drop while the ICE comes up to temperature. If the SOC drops too much during ICE warmup, it will be tough to get back to SOC and engage gear mode.

The HV reset can jump the gear mode setpoint, and get the car back into gear mode.

ClarityBill

..."RPM data is a symptom of gear mode, and not the cause"...
What came first...the chicken or the egg? Point is...whether engine clutch engagement occurs because of RPM or because gear mode sets RPM...regardless it kicks in at given RPM/speed.

Gear mode is determined by the SOC.
The data collected off the Clarity I drive indicates very little correlation to the SoC vs engine clutch engagement.

SoC, whether 30% or 90%, has little bearing on engine clutch engagement for the Clarity I drive. Just last week I drove 150 miles and started with 90% SOC...used EV mode at the destination...and returned home driving 150 miles on SoC 30%...engine clutch engagement occurred as normal though slightly less due to uphill bias on the return trip which is expected.

Just data. Mo folks need to report mo data.

 

[David Towle]

David Towle

Data collected on the Clarity I drive indicates it is predictable. Data has been collected and observed through all types of driving conditions and for all intents and purposes...it acts the same. Sure temps/conditions may alter the pattern somewhat but the data curve remains within stated parameters.

My comments are based on data and data only. I report the findings. If the Clarity you drive behaves differently...therein lies the problem...which we are collectively ciphering on.

HagerHedgie

OK thanks. The no gear mode conditions happened to me several months before I had my dash go blank and I had to pull the battery negative terminal to reset everything, and under cold weather conditions (around 0F). Maybe it will behave different now.I will let you know if i run into the no gear mode condition again this coming winter.

 

[Clarity_Newbie]

I normally wait until the ICE rev's up a little: Are you watching EV range, and resetting before ICE rev?

I don't find gear mode to be that mysterious, and it sounds like you don't either. This is my impression, do you agree:

It appears the control system uses an SOC setpoint to control the gear mode operation. A different setpoint is used to control the ICE start and stop. When you enter HV mode, both setpoints take a value close to the SOC when HV started. When I do a HV reset, the gear mode setpoint is changed (reduced), but the ICE start/stop is not changed (it stays higher): This keeps the ICE from cycling on and off as much.

A side note:
It looks like you are using EV range to monitor SOC. I use an OBDII monitor, and watch SOC directly. I find the
EV-range control-band changes with the full-battery range: The computer directly uses the actual SOC percentages for control range.

ClarityBill

I don't find it that mysterious at all. Still some unknowns sure but it is pretty predictable at given speed/request for power (ie) RPMs steady or rising due to increased request for power?

 

[Clarity_Newbie]

I mean the battery’s state of charge. You can go 300 miles in gear mode.
If you hit HV when the EV range is 30 miles then the car will tend to stay in gear mode (once the ice is warm) at speeds above 45mph as long as the EV range is at least 27. If, due to high energy demand, the charge level drops below that the gear will disengage and the revs will go up.
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HagerHedgie

Therein lies the problem with debates like this...everyone uses "their Clarity" as the "basis of information or perspective" or "what it is supposed to act like". Problem is not all Clarity's act the same. As I have noted, the Clarity I drive appears to act "differently" then yours. No right or wrong...just different reference points.

I tend to present my findings as data based and typically offer no opinion if the Clarity I drive is representative of the majority or not. I just offer what I find via data collection and offer it up for others to weigh.

Collectively perhaps enough data can be collected to learn mo n mo. Personally I value everyone's input and give all points of view consideration. That is the way it is supposed to work.

 

[Clarity_Newbie]

My other cheap OBDII unit has a memory card for long-term recording, but I have immediate questions that don't need long-term studies. Also, that one does not display SOC, which is critical in understanding the Clarity. It also has the option of alarm when RPM's exceed a level. I set it to alarm when RPM went over 3K, and I would reset the HV. The alarm got annoying in a snow storm, when EV range went to zero, and RPM could not stay below 3K: I have not used it since then.

ClarityBill

If you are referencing the PLX device w/SD card we discussed months ago...the device itself is perfectly capable of recording SoC etc. Problem is the native app which is provided by PLX and the only way to set the OBDll device into self-run mode is seriously lacking in features. If PLX would upgrade/update this app to current specs n standards...it would be a much more attractive option. I have emailed them twice but so far i haven't seen any improvement in the app.

I use the PLX self-run mode when I desire long term data collection requiring minimal user interaction. I have run PLX with Torque Pro and it displays much mo data...including SoC.

If you are using a different device...then disregard. lol

 

[ClarityBill]

It looks like Clarity stays in Atkinson mode for ‘all’ driving, after the warmup is complete at 1500 rpm. I was at 4400 RPM during a hill climb, and the I-VTEC stayed engaged. There were minor changes to valve timing, that were relatively linear to the engine RPM.

I used the AutoEnginuity OBDII system to monitor Atkinson activation.

I found several parameters that seem to reference the Variable Valve Timing system (VTEC). I logged all of these for my first run, but they seemed to follow the first parameter, so I only logged the indicator command and VTC angle for subsequent runs.

I-VTEC Indicator Command (Bit) [0 - 1]
Rocker Arm Oil Control Solenoid Bank 1 (Bit) [0 - 1]
Rocker Arm Oil Control Solenoid Bank 2 (Bit) [0 - 1]
Solenoid Return Signal (Bit) [0 - 1]
VTEC Oil Pressure Monitor Switch Input (Bit) [0 - 1]
VTEC Pressure Switch Bank 1 (Bit) [0 - 1]
VTEC Pressure Switch Bank 2 (Bit) [0 - 1]
VTEC Solenoid - Commanded (Bit) [0 - 1]
VTC System Control (Bit) [0 - 1]
VTC Advance Angle - Commanded (Deg) [-20.0 - 107.5]
VTEC Changes To Hi V / T (Bit) [0 - 1]

When the engine first starts, it stays at 1500 rpm during the warmup phase. The VTEC is not engaged during this time.

VTEC is disengaged anytime the engine shuts off (while in HV mode), but is reactivated when the engine starts again.

I was disappointed the engine did not leave Atkinson mode for the hill climb. The engine was over 4000 RPM, and obviously working hard.

The articles I read show the Clarity has a two-intake cam system. One is Atkinson, and the other is standard 4-stroke. The valve selection is with oil pressure solenoids. The parameters available in OBDII seem to confirm this design.

I have done some more runs, and the Clarity has stayed in Atkinson mode for all runs. I try to keep my engine away from the high rpm's, so there may be an upper limit. I wish I had this recorder on for my run with over 5000 rpm, but I don't want to replicate that one...

I am wondering if the 'Angry Bees' would be people experiencing the ICE coming out of Atkinson mode. I am thinking the exhaust noise would be significantly louder. (Atkinson reduces the pressure energy wasted out exhaust pipe)

I have convinced myself that the ICE is louder at 1500 rpm during the warmup phase (non-Atkinson), than when it hits 1500 rpm later in the run.

 

[Landshark]

FWIW: I had an opportunity while in gear mode to run the speed up to 85mph. Yes, miles not kilometers. It remained in gear mode up to that speed.

The engine noise was hardly noticeable. I believe I have experienced the higher revs that some find unsettling while climbing mountain passes with the batteries in a low SOC. At first it seemed unusual, then I figured it’s a 4 cylinder Honda, I can’t hurt it.

 

[HagerHedgie]

I wanted to revisit this thread. I have noticed in lower temps of 40F and below, the gear mode is less predictable. I’m not sure why.
My theory is that it’s Probably due to some algorithm that protects the battery from high charge rates at low temperatures. I think Honda could have done a much better job at this. I didn’t engineer the car but I can’t help but feel some corners were cut in the programming.
I like my clarity mostly. Particularly the $8900 in tax credits.
I hope to get a Tesla next time.


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[neal adkins]

I wanted to revisit this thread. I have noticed in lower temps of 40F and below, the gear mode is less predictable. I’m not sure why.
My theory is that it’s Probably due to some algorithm that protects the battery from high charge rates at low temperatures. I think Honda could have done a much better job at this. I didn’t engineer the car but I can’t help but feel some corners were cut in the programming.
I like my clarity mostly. Particularly the $8900 in tax credits.
I hope to get a Tesla next time.


Sent from my iPhone using Inside EVs

The Clarity's complex clutch/charge system may go out of direct drive to provide more charge during colder temps. It would make sence during colder temps due to more demand placed on the ev batteries from the heater.

 

[David Towle]

I wanted to revisit this thread. I have noticed in lower temps of 40F and below, the gear mode is less predictable. I’m not sure why.
My theory is that it’s Probably due to some algorithm that protects the battery from high charge rates at low temperatures. I think Honda could have done a much better job at this. I didn’t engineer the car but I can’t help but feel some corners were cut in the programming.
I like my clarity mostly. Particularly the $8900 in tax credits.
I hope to get a Tesla next time.


Sent from my iPhone using Inside EVs

Glad to see others are finding the unpredictability of gear mode at colder temps. Sometimes when I do the quick reset it goes right back into gear mode, other times it takes a half hour. I have not experienced this winter the very cold conditions where the car would not go into gear mode at all.

But I did find something new recently. As I've mentioned I never plug my car in due to the high cost of electricity here (that will change when I move to Florida soon). So I probably use HV Charge more than anyone else here. I have found the number of miles gained in HV Charge versus those driven varies wildly, but does not strongly affect total gas mileage. For instance I recently drove from New Haven to Old Saybrook, about 25 miles on a fairly flat interstate, at 71 mph, and only gained 1 electric mile in that time! Normally I get 5-7 added over that highway distance. And the wind was at my back, temps in the 30s. That tank gave me 39 mpg well within my normal winter range of 38-43.

Too bad I'm not competent to set up an OBD recording setup like others.

Apparently sometimes the engine is willing to work hard and add miles, sometimes it isn't.

 

[neal adkins]

Glad to see others are finding the unpredictability of gear mode at colder temps. Sometimes when I do the quick reset it goes right back into gear mode, other times it takes a half hour. I have not experienced this winter the very cold conditions where the car would not go into gear mode at all.

But I did find something new recently. As I've mentioned I never plug my car in due to the high cost of electricity here (that will change when I move to Florida soon). So I probably use HV Charge more than anyone else here. I have found the number of miles gained in HV Charge versus those driven varies wildly, but does not strongly affect total gas mileage. For instance I recently drove from New Haven to Old Saybrook, about 25 miles on a fairly flat interstate, at 71 mph, and only gained 1 electric mile in that time! Normally I get 5-7 added over that highway distance. And the wind was at my back, temps in the 30s. That tank gave me 39 mpg well within my normal winter range of 38-43.

Too bad I'm not competent to set up an OBD recording setup like others.

Apparently sometimes the engine is willing to work hard and add miles, sometimes it isn't.

I have a suspicion that the range prediction could be making adjustments. I charged last night to 100 percent and it showed I have 63 miles ev range. I am not using heater or ac very much. I've seen a few miles of range disappear rapidly times. Moral of the story is even after the dealer did an update for the range it still is flawed in my experience. That's why I think your overall gas mileage was in track. So I don't rely on the range estimate but just look more at current soc and go from there. This issue has caused many a clarity owners grief. But I do relate to the car not performing consistently in hav charge. I have seen a hiccup in cold climate where it would not gain any range. It's like I selected charge mode but the computer was overriding it. After I stopped for lunch and restarted things went back to normal.

 

[Landshark]

HV charge can provide the most aggressive charging protocol in warm weather. I’ve only used it a few times. In one case it brought the battery level up from 2 bars to 10 bars in about 30 minutes, after ~5 minutes of “warm up”. That equates to roughly 40 miles of added range per hour. Of course it stops charging at 12 bars. This is approximately a 1.0C charge rate compared to ~0.4C with a 32A Level 2 charger.

Lithium battery manufacturers provide a range of temperatures for which their batteries will accept a charge. Typically, 32F is the low limit, some go as low as 25F. It is likely that charging via HV Charge in mid-30’sF will be limited.

 

[Phil_Meyers]

HV charge can provide the most aggressive charging protocol in warm weather. I’ve only used it a few times. In one case it brought the battery level up from 2 bars to 10 bars in about 30 minutes, after ~5 minutes of “warm up”. That equates to roughly 40 miles of added range per hour. Of course it stops charging at 12 bars. This is approximately a 1.0C charge rate compared to ~0.4C with a 32A Level 2 charger.

Lithium battery manufacturers provide a range of temperatures for which their batteries will accept a charge. Typically, 32F is the low limit, some go as low as 25F. It is likely that charging via HV Charge in mid-30’sF will be limited.

What happens with regen while charging ?

 

[The Gadgeteer]

Don’t forget using the heater in cold weather has a big impact. The power going to the heater will reduce the ability of going into/maintain gear mode and reduce the amount of power available to charge the batteries during HV Charge mode.
Regardless you will still get better mileage than just about any non hybrid gas mobile.

 

[Landshark]

What happens with regen while charging ?

Possibly the same thing that happens when there is excessive regenerative energy and the battery is near 100% SOC.

Or the current from HV Charge may be reduced by the BMS so that the combined energy from the 2 sources does not exceed a specified parameter.

 

[css28]

Don’t forget using the heater in cold weather has a big impact. The power going to the heater will reduce the ability of going into/maintain gear mode and reduce the amount of power available to charge the batteries during HV Charge mode.
Regardless you will still get better mileage than just about any non hybrid gas mobile.

Doesn't the car use engine coolant for heat when the engine's warmed up?

 

[Danks]

What happens with regen while charging ?

In HV Charge the engine basically does the same thing with regen braking as it does in normal HV mode. If you are getting regen going down a long enough hill the engine will turn off in HV Charge. (At least it does on my 2019.)