Clarity Issues

I measured 0-60 times at 9 seconds for my Clarity PHEV (Econ/Normal/Sport, all the same if you floor it). It was cold, maybe 30F, but I was coming from garage around 50F. This will probably limit battery performance some. I will test again when 80 or 90F when battery will produce more power. For comparison, my Gen 1 Volt I measured at 10 seconds or so in identical conditions. Driving this fast will make the Clarity sound like a bunch of angry bees (buzzing at a constant high RPM).

On EV only (Econ without pushing past detent/click point on go pedal), the Clarity was 0-60 in about 13 seconds. This doesn't sound particularly fast, but it is faster than other traffic starts most of the time, and the 5-45 acceleration is pretty good, faster than most other traffic usually drives. What I am saying is it likes to drive briskly should you want to.

I measured using Torque! Pro, multiple runs each direction.

 

The Clarity uses the same I-MMD (intelligent Multi Mode Drive) two motor hybrid system that was originally used in the 2017 Accord. The best explanation of that system I have found is the caranddriver article;
https://www.caranddriver.com/features/explaining-the-honda-accords-shrewdly-designed-new-hybrid-system-tech-dept
The Clarity has two motors both can also be used as generators. The first motor is the propulsion motor which is connected thru gears to the front wheels. It is the only motor use to propel the vehicle. It is used when decelerating or breaking as a generator to put power back into the battery. The second motor is the starter/generator motor which is used to start the engine when needed and to provide power to charge the battery or to power the propulsion motor when the engine is running. There is also a clutch between the engine and the propulsion motor which may engage at speeds over 46 mph when in HV mode.

There is no CVT transmission on this vehicle. The gear ratio is always fixed. In hybrid mode with the clutch not engaged between the engine and the propulsion motor there are two separate systems. The engine is generating power to charge the battery and/or to provide power for the motor, but the two systems run independently from one another. At speeds above 46 mph in hybrid mode, the clutch may be engaged and the engine is directly connected to the wheels through a set of fix gears.
The Clarity also has no planetary gears in the drive train. There is a planetary gear in the grey area of the caranddriver article, but it is used to allow the two front tires to turn at different speeds when the vehicle is turning. (Same reason there are planetary gears in a differential)

If I know I am going to be driving far enough to drain the battery, I will put the car in HV mode when I am traveling over 46 mph. In that case the clutch will be engage and the engine does not sound like it is racing. Under speed of 46 mph I put it back into EV mode, but if the battery is drained the engine will generate power to supply the propulsion motor and will race depending on how much power is required.

 

It is a CVT transmission, just not what you are thinking of as a CVT. It uses some variation of a planetary gear setup (epicyclic gearing) just without a ring gear. Depending on the RPM of the motors they can allow the engine to run at different RPMs.

Read the first comment on that article for CandD you link to and they are complaining about technical issues with the writing.

The tech specs even indicate the varying gear ratios.

https://automobiles.honda.com/clarity-plug-in-hybrid#

Electronic Continuously Variable Transmission (E-CVT) with Sport Mode and Deceleration Paddle Selectors
Ratio
2.454 ~ 0.805

Final Drive
3.42

 

PS, those CandD and other articles all mislead and seem to link back to an old source.

The Clarity works similarly to a Volt or Prius in that it is a power split transmission that can operate in either series or parallel mode. Yes, it doesn't have a classic planetary as such (might still be called one, not sure), but all these physically link the engine to the wheels directly through gears using a clutch or more than 1 clutch, depending on what little variations they want.

http://www.mate.tue.nl/mate/pdfs/8335.pdf

 

FWIW, I ran my VIN on the VIN decoder on the NHTSA site and it said it had a CVT. I’m w Viking on this one.

 

Hi Viking79, although the Honda Clarity and Chevy Volt are both plug in hybrids and have similarities, they do differ in their transmissions.

The Chevy Volt 2 has planetary transmissions as explained here: http://gm-volt.com/2015/02/20/gen-2-volt-transmission-operating-modes-explained/

As mentioned in another post on this forum: "The first generation of this drive train was released in a short run of Accord plug in models in 2014, this is the update unit as they took a few years to clean up the rough spots" the Clarity is a development of the i-MMD system in the previous Accord as explained here: .

As you said, they are both power split transmissions that can operate in either series or parallel mode, but the Honda patented one is simpler and requires the electric traction motor to accelerate the car to the speed at which the single clutch can connect the engine to the wheels.

 

For nerds like myself, I think that the Honda patent which describes the Clarity arrangement is here, happy reading

 

Sorry Viking79, you're wrong. The Clarity has no transmission and the gear ratios are all fixed. There is no continually variable transmission. The reason the engine varies speed under 46 miles per hour is because it is an independent system running at variable speeds depending on the amount of current the propulsion motor needs and controlled by the vehicles computer.
I stand by my statement.

 

Fidzio, thanks for info and link. The question of CVT, no CVT, eCVT, or CVT-e may just be a matter of semantics as to exactly how it’s implemented.
You’ve definitely earned your 10 smileys from our previous discussions on the transmission. PM me w address and I’ll send you a little piece of 3M 8 mm paint protective film (left over from protecting door sills) to cover the blue back of your key fobs to prevent scratches. It’s the least I can do for such a nice Canadian.

 

Well that settles that! Thanks Fidzio and bpratt for the technical background that corroborates every article and video I've combed through about the technical details and differecnes in Honda's innovative iMMD drive.

We can thank Honda's Marketing dept for using the term eCVT to make this more difficult.

 

I agree. I think they should have called it eCVEG (electronic Continually Variable Engine Generator) instead of Transmission. To me an automobile transmission is a series of gears (or metallic belts in a CVT transmission) that changes the gear ratio from the engine to the wheels. The Clarity uses a fixed gear ratio between the propulsion motor and front wheels and varies the engine speed to provide the correct generator output to the propulsion motor.

 

When clutch is disengaged, the 2 electric motors can act as a CVT between the running engine and the wheels. Pretend that the electrons flowing between the two are your virtual belt. This is how the Volt, Prius, Energi, etc can operate as CVT. They really are CVT, just called electronic variator instead of a belt variator. Hence the name e-CVT.

When the clutch is engaged the engine is connected directly to the wheels through a simple gear reduction transmission.

Please remember that transmission just means how you transmit power from the power source. The Volt can do this through its gearing as well (the contested mode that made environmentalists hate it for some reason, even though it is more efficient).

 

Thanks, will watch the video later. I was never trying to imply that they are the same, only that they are similar in that they are both power or input split devices. They have slightly different modes of operation, but they are for sure "transmissions" (the mechanism by which power is transmitted from an engine to the wheels of a motor vehicle), and multi-mode ones at that. I.e., both eCVT mode and simple gear reduction mode are common between Volt and Clarity (implemented differently).

Each company has to make their own multi-mode transmission if they don't want to pay licensing fees.

 

The difference is the Prius and the Volt use both motors to drive the vehicle through planetary gears which is a mechanical transmission. The Clarity only uses the starter/generator motor to start the engine (as a motor) and to generate electricity to power the propulsion motor or charge the battery. So the Clarity transmission is strictly electronic and the Volt and Prius are mostly mechanical. So I guess we agree. My problem, with my mechanical engineering background is I have trouble calling the drive mechanics of the Clarity a transmission since there is no gear changing.

 

Has anyone figured out how to make the ice turn off (without a restart) after it kicks on for whatever reason. As soon as I see that white line I imagine dollars being sucked out of my wallet...lol...

 

Brady, I hate that feeling too.
I think the consensus is that when the ice starts, it’s going to run until it warms up to a certain level even if it’s not needed after initial request. That might be to prevent overly large numbers of cold starts and condensation which are both bad for engines.

 

This happened to us on our Santa Fe trip, with one distressing side note - mine dropped to 0.0 EV range, and HV Charge mode would not work - over twenty miles and not even 0.1 on EV range gauge. Still, I think it works best this way because if I have been driving HV I usually want it to restart in EV anyway.

 

But if it kept HV then every time you used it the next day you would drive in HV instead of EV. That seems worse

 

I wasn't clear - I was voting FOR switching back to EV (its default mode).