I think what irks me about this feature (and perhaps some other owners by the sound of it) is that it happens in situations where it is so obviously unnecessary. While the amount of gas used to warm up the engine may not amount to much, it simply flies in the face of efficiency. The two most common scenarios where I have had engine starts while braking with a full battery are leaving home and leaving work. In both cases, I am moving a few hundred yards and then coming to a stop sign from maybe 20 MPH and on the brake pedal softly for a few seconds. Hard to imagine a circumstance where the friction brakes are not up to the task of stopping the car from 20 MPH. If I was rolling down a mountain road at highway speed, I can see the case for engine braking. I have learned how to successfully work around it in my common situations, either by stopping charge short of 100 percent or, if I know the battery is charged to 100 percent, by shifting to neutral before touching the brake pedal.
Battery fully charged but running in full motor/gas mode?
- Thread starter Jason90405
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fotomoto
Active Member
To reduce speed on major downhill descents, hybrids can use the MG to spin the ICE as an air compressor via variable valve timing and fuel shut-off (if warmed up already). My Prius has B mode while my C-Max calls it hill grade assist. In both, it sounds like the ICE is running "normally" but the fuel economy gauges max out (999mpg).
As to the Clarity PHEV, one of the conditions that will almost always exist when regenerative braking energy triggers the ICE, will be a cold ICE. It isn’t a Prius or a C-Max. Those cars will perform differently than the Clarity, particularly if we are discussing the non-plug-in hybrid models. Those engines are on and off constantly and the tiny battery wouldn’t be able to accept a high level of regenerative energy, so it just uses an already warm engine to provide some engine braking. The driver won’t even notice.
The Clarity, on the other hand, defaults to EV mode on start up. It can be driven 20-odd miles to a destination and 20-odd miles back to the original starting point completely as an EV. Much like the Spanish Inquisition, no one would expect the engine to fire up when stopping for a red light, 5 blocks after beginning a drive. It will then continue to run through a warm up cycle, burning fuel, for 3-5 minutes. Some owners have reported that the engine will run indefinitely, once started, and will only stop if the car is shut down.
It seems wasteful and inefficient for a vehicle that is equipped with 4-wheel disc brakes that are more than capable of stopping the car and allowing it to remain in EV mode.
fotomoto
Active Member
Even though these other hybrids have different sized batteries and, just as importantly, battery chemistries, the behaviors are the essentially the same as the clarity.
The Clarity is not different. It can activate the ICE ANYTIME (lots of FAQ’s here about that). Even the Volt has a couple of scenarios that will automatically start the ICE so even it wasn’t 100% EV operation 24/7.
If I lived on top of a hill and had to grapple with this every morning, I’d want a Hill-Top reserve charging feature to allow room for regen and not replace brakes every xx,xxx miles like a regular vehicle. For a plug-in without this setting, I’d setup a timer on the EVSE and short-charge as best as I could. Another suggestion from other forums is to set HEAT to MAX to burn off some kW before the descent via pre-conditioning while unplugged.
As mentioned previously, I can activate my Energi’ s ICE via the brake pedal even on level ground if: I recharge on L2 a hot battery in hot conditions and then drive it in L gear (more regen). Our workaround? We avoid “opportunity” charging during the day and rely on hybrid operation instead. Our Clarity is fine in this same scenario (no major hills locally). It’s liquid cooled pack has a much higher threshold than the air cooled design.
Would I prefer in my C-Max scenario for it to only use brakes? YES! Would I prefer it to only use brakes in the living on a hill top scenario? NO!!!!!!! This is a situation where the next level of AI and GPS will combine things like “seeing” the road conditions ahead, understanding the drivers driving habits, their route, etc to decide to either use the brakes or regen. Toyota and Hyundai have some rudimentary versions of this right now. Heck, even my ancient C-Max has EV+ which learns my home and office locations and allows an extra EV mile or two pulled from the hybrid portion of the pack so one can reach these destinations without activating the damn ICE (a block from home). Nice feature.
How so? By flooring the accelerator? I avoid that maneuver whenever possible. I’ve driven for hundreds of miles, for weeks on end without activating the ICE. I don’t want the frigging ICE to come on, unless I want the ICE to come on. Does that make sense?
I don’t want to dick around like that. I want to get in the car, operate it as an EV, because that’s the mode I selected, and not have the ICE start. Who, on God’s green Earth, wants to turn the heat on Max if it’s 100 degrees outside? Is this a rational solution? Why should I have to micromanage charging to avoid an undesirable outcome? I don’t limit filling the fuel tank in the Clarity or any other vehicle to prevent an undesirable outcome.
Artificial Intelligence is an appropriate description. It is mostly Artificial. In the case of the Clarity, it isn’t intelligent enough to use the brakes. It isn’t smart entry know that I’m not about to rear end an oncoming vehicle on a curve. Fortunately, a human included a switch to disable the Artificial Intelligence. I’m not going to cook the brakes prematurely slowing for a curve or stopping at a few red lights. The brakes only need to be used when the battery is full. He’ll, this intelligent device won’t even let me type hell. There, it did it, finally. I drove my last car 145K miles and replaced the pads and rotors once. Too much is made of wearing out the brakes.
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fotomoto
Active Member
Common remarks across plug-in forums over the last decade. Ultimately you want a BEV without the petrol baggage. In the early days (circa 2011), I use to feel this way too but not any more. Now a decade later, I just read this morning from a BEV owner about range:
“ I am tired of hearing that this much range is not required. I have owned a model 3 since 2018. It was originally rated at 310 miles, then upgraded via software to 325 miles. However, three years and 33k miles later, the max it charges to is 285 miles. In addition, on long drives, with a family of four in the car, at 80 mi/hour, it barely gets 80% of that i.e. 228 mi. With auto-pilot (that's one big plus), we can easily drive 6 hours or more without any fatigue. So STOP telling me more range is not important. When they say 400 miles or range is needed, it better be REALLY 400, which means the car should "start" at at least 500 to account for battery degradation over time and real world scenarios.
We don't want the acceleration (now THAT'S not needed), but range IS.
Disclaimer: Long TSLA (check out my previous comments before you think I am anti-TSLA).”
A 500 mile EV is going to be a $100,000+ vehicle in the 2021/22 timeframe. Umm, OK. I’ll stick with a PHEV and all of its “warts” till the cons outweigh the pro’s. I’m thinking parity is about 10 more years away going by the rate of advancements happening today. This includes COSTS.
Sorry, but you’re dead wrong on what you think I want.
Let me emphasize that I do not want a BEV, of any sort, now, and likely, not 10 years from now. Understood?
To me, a PHEV is a much more versatile vehicle. I’m more than happy to lug around all that baggage. Thank you for your concern. I believe that the fact that the car starts the engine, while braking under certain conditions, demonstrates a poor engineering decision. I actually like to call it a flawed design, even though it accomplishes the intended goal. In my humble opinion, a PHEV, while operating as an EV, should not start the engine, to slow down or stop, under any circumstances. Make sense?
I’m obviously missing the point of the quote that you posted as it pertains to this discussion. It just sounds like a pissed off BEV owner who bought a car that doesn’t deliver as promised.
fotomoto
Active Member
Like a BEV.
I should have said, “You want a BEV without the BEV baggage”.In some instances of ICE activation, I’d rather want friction brakes but for major or frequently reoccurring events (living on a hill) I’d want regen to battery reserve first with ICE activation blended with friction brakes as the backup/secondary.
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No, I still don’t want a BEV, with or without baggage.
If there’s no battery reserve to accept the regenerative energy, I’d prefer friction brakes exclusively. I’d want it to remain exclusively friction brakes until there was adequate reserve battery capacity to accept the regenerative braking energy.
It defies logic that a car operating as an electric vehicle would start an internal combustion engine to slow down. I don’t know how else to say it.
Mass Clarity owner
New Member
Offering up my data point, in case it helps. And also offering up a few theories.
I've owned the Clarity (base model) since Sept 2020. It is a used 2018 model. I have never seen this behavior happen (* see below, for a possible exception), where the ICE kicks in as a response to getting rid of excess energy when the battery is fully charged. I am still enamored and curious as to how the car works, so I watch and observe closely what is going on. So I cannot imagine I have missed it.
My typical start of any journey from home base:
car fully charged (using just our household line, no 240v level 2 charger)
default EV mode
back out of the driveway, say, 50 ft
forward 50 yards of level driving
fairly steep (5% grade?) downhill for another 50 yards, coming to a complete stop (mostly); always need to brake, always flick the paddles to 4 chevrons and also depress the brake pedal
then level driving onwards
In this scenario I have never had the ICE engage.
* There is only one occasion (now that I read all your postings about the ICE coming on) when this might have occurred with my car. This was when I charged at a state park with a level 2 charger (charging to full) and then drove away. It was level ground, but I had to immediately use braking for stop and go traffic. I heard the ICE go on and I was confused. As this happened early on in my ownership, I thought it must have been some routine engine maintenance procedure. So I did not worry about it.
Reading your stories/scenarios and comparing them to the factors of my typical scenario, here are some questions/theories:
I've owned the Clarity (base model) since Sept 2020. It is a used 2018 model. I have never seen this behavior happen (* see below, for a possible exception), where the ICE kicks in as a response to getting rid of excess energy when the battery is fully charged. I am still enamored and curious as to how the car works, so I watch and observe closely what is going on. So I cannot imagine I have missed it.
My typical start of any journey from home base:
car fully charged (using just our household line, no 240v level 2 charger)
default EV mode
back out of the driveway, say, 50 ft
forward 50 yards of level driving
fairly steep (5% grade?) downhill for another 50 yards, coming to a complete stop (mostly); always need to brake, always flick the paddles to 4 chevrons and also depress the brake pedal
then level driving onwards
In this scenario I have never had the ICE engage.
* There is only one occasion (now that I read all your postings about the ICE coming on) when this might have occurred with my car. This was when I charged at a state park with a level 2 charger (charging to full) and then drove away. It was level ground, but I had to immediately use braking for stop and go traffic. I heard the ICE go on and I was confused. As this happened early on in my ownership, I thought it must have been some routine engine maintenance procedure. So I did not worry about it.
Reading your stories/scenarios and comparing them to the factors of my typical scenario, here are some questions/theories:
- could this occur in conjunction with level 2 charging?
- could traveling first in Reverse make a difference?
- could this be some sort of firmware difference between our cars?
Thanks for the perspective.
Level 2 charging could be a contributing factor. Particularly, if driving immediately after charging. It is likely that the battery is warmer after L2 charging. Much like you, I’ve charged almost exclusively using L1, with a few workplace opportunities that had L2 charging. In those cases the charging was completed and the car was moved from the charging spot several hours before driving.
In my experience I don’t believe that driving in reverse, first, is a factor. When in LA, I backed into a carport, charged overnight and pulled forward to the street where there was a mile of slightly downhill to a freeway entrance. The engine never started, in probably 200+ attempts, despite a stop sign and two traffic lights. Now in Oregon, I pull forward into the garage and charge. I back out about 100’ to a turn around spot and then head down the driveway 500 or so feet to the road that is downhill in either direction. The engine has never started.
Anything is possible with technology, however, my spidey senses tell me that a difference in firmware/software is unlikely.
Maybe then it would be like driving an Accord Hybrid (and Insight), which turns off the gas and spins the deadened engine to use up excess power.
JFon101231
Active Member
Interesting - I guess that would be slightly better than current, including its more "temporary" (rather than ICE running for the 5 mins I'm in town and could most effectively use EV which also would reduce likelihood of it happening AGAIN).
I'm with Landshark, IMO the current design is poor
I'm with Landshark, IMO the current design is poor