Battery fully charged but running in full motor/gas mode?

You can ask Chrysler too, because my 2018 Hybrid Pacific will do the same thing. It’s only happened to me a couple of times when going down a steep hill starting out at 100%.

 

The PHEV is more prone to consistent overcharging (since people plug it in every day) and so they are probably much more careful about keeping a buffer on the battery. The pure hybrids probably bake in a buffer too, but are willing to blow through the buffer occasionally under the theory that it would be a rare occurrence (plus they may bake in the buffer like the HV charge mode--60 someodd %)

 

Wow. When you have finally come to the end of your time with your Clarity, don't sell it or trade it...have it bronzed. Mine drives me crazy with ICE startups on a full charge going down the hill I'm on. I can't even look at the paddle, or the brake pedal without it firing up.

 

Don’t the non-PHEV hybrids have relatively small capacity batteries? Somewhere in the 1KWh range? We rented a Ford Fusion hybrid for a week and it rarely got above 70% charged and rarely went below 40%.

I’d guess that a car like that isn’t capable of creating the regenerative energy that a PHEV or BEV generates. That small battery just couldn’t take it. So, it gives a little and takes a little and just stays in that 40-70% range. It was an awful driving experience.

 

The Clarity Electric (and BEVs in general) just reduce the regen energy produced when the battery is full or very cold. The driver has to use the brake the friction brakes to make up the difference. There is no reason for "excess energy" to be created when the battery is full, the amount of regen is variable (the whole purpose of the paddles).
Some BEV owners complain that it is dangerous to need to use the brake pedal when you are used to not doing so. Maybe Honda was trying to keep a consistent regen level so lifting off the throttle always produced the same amount of slowing.
The Clarity doesn't allow for more than a middling amount of regen even in it's strongest mode and there is only a nod towards true one pedal driving. BEVs with a full one pedal driving mode have figured out how to cope without having a running ICE to somehow shunt energy away from the batteries. Honda has done the same on the Clarity Electric. Why the PHEV acts the way it does (for most owners?) is puzzling.

 

We're on a top of a hill too. Our driveway also is steep. I don't recall the engine ever starting when going down. We've already put 40k miles in a year and a half.

 

There’s no doubt that it does happen. What is irksome, is that Honda opted to utilize the engine in a situation where the amount of regenerative energy produced exceeds the ability of a fully charge battery to accept that energy. The brains of the operation knows the battery SOC at all times. It limits regenerative energy when the battery is at or near a full charge. Yet, it isn’t smart enough to limit regen AND apply the friction brakes a bit more. Instead, it fires up the engine.

This is on a car that is promoted as being extremely efficient. A car that defaults to EV mode upon start up. A car that has the potential to greatly reduce carbon emissions. However, when we do our part and fill it with electrons, we discover that it is designed to fire up the engine when we hit the brakes.

You can’t make this stuff up.

 

Some BEV’s allow for living on a hill by having the option to stop fully charging the battery (80% typically) thus allowing some reserve for the decent.

Hot or full batteries can’t accept a lot of regen. Hot+full can mean no regen+ICE start. Here is south Texas, I can get my Energi to ICE start via regen on a level street if the battery is hot+full from a level II session. Being air-cooled, its parameters are even lower than the Clarity.

Landshark is in Oregon. Phil Meyers is located where?

 

I think many are too hard on the Clarity PHEV designers with respect to the engine starting during braking when the traction battery SOC is high. Compared to the Accord hybrid, the Clarity is not running in EV mode while Accord hybrid engine is usually running (and warm). So, when the Clarity engine is turned over for absorbing excess electrical energy, the engine needs to complete a warm up cycle and use fuel. And, turning an ICE engine off when slowing down (either coasting or braking) is not uncommon for normal ICE vehicles. My 1991 Toyota pickup turns the engine fuel injection off when the accelerator pedal is not pressed and the engine is running at higher than about 1500 rpm.

The Clarity PHEV's engine running during moderate or hard braking when the traction battery SOC is high is not, in my opinion, a design fault. Some have wondered why disc brakes are not just used to a greater extent in such situations. Note that the Clarity PHEV brakes are about the same size as those on the Accord Hybrid while the Clarity PHEV has a nearly 700 pounds greater curb weight. The Clarity system as a whole is obviously designed around having the regen providing a significant portion of the braking force and energy absorption. I am of the opinion that when cold the Clarity brakes can adequately stop the vehicle without overheating. However, that is probably not the case when the brakes are already hot from prior use. The Clarity PHEV does not appear to have any brake (disc or caliper) temperature sensors, so the vehicle's electronic management system does not know if the brakes are hot. So, the system just assumes, whenever regen cannot be used when the traction battery SOC is high, that the engine needs to absorb some of the energy (thus, starting and running until warm). I do wonder when the engine is already warm, if the engine will actually keep running after the braking engine absorption is no longer needed. I do not plan to test this.

Finally, we often need to brake going down a hill when leaving home after a full charge. The engine sometimes started when braking. We got around the engine starting by turning on both seat heaters to high when leaving home with a full charge. We seem to need only about three minutes of seat heating to eliminate the engine starts when braking moderately or hard.

LeoP

 

FYI: It was 100F in Oregon yesterday.

 

Would the BEV be unable to slow or stop if it were pointed downhill, on a hot day, immediately after a full L2 charge? It must have some way to stop that doesn’t involve running an internal combustion engine.

I’d imagine that the larger capacity battery is able to absorb some regen, but it might also ask the friction brakes to join the party.

 

We hit that in March.......

Of course, it’s the average that’s important. Here in the summer my garage stays about 10 degrees below ambient. During peak summer temps and parked outside, my Energi battery can often stay above 100f during the day and well into the night. 113f is the software cutoff and it’s ICE only after that till it cools down. Drivers that try to level II charge the battery at those temps are greeted with the ICE only message upon startup.

 

Sorry, I just don’t see the relevance of comparing a PHEV to a Hybrid, or a BEV for that matter.

Put me in the group that colors it a design fault, please. A car which operates as an EV by default, that needs to run an ICE to slow down, is a car with a design fault.

What amount of braking effort would be required to heat the brakes to the point of reduced braking performance? Would several, spirited 0-60-0 efforts do the trick? Just a couple of 0-60 runs will reduce SOC by 5-10%. Once that’s done, we’re back to full regen braking capability. With the exception of several miles of a steep downgrade, immediately after a full charge, it would be a challenge to heat up the brakes without depleting the battery to some degree.

There just has to be a more elegant solution than running the ICE.

 

I disagree... In my opinion, this is a triviality in the life of the vehicle and not worth all of the discussion that it seems to inspire.
Energy is energy, and if the battery can't take it, you have to dissipate it somehow. You could dump it to the friction brakes (then people would squawk about excessive brake wear). Dumping it to the engine has some merit, and it seems clever to me. There is really no significant wear, and the engine is just idling for a short time and the gas that's used is truly trivial. There are reasons to run the engine occasionally anyway, and this fits in with that desire.

 

Well, since you’ve attempted yet again to squash a discussion you disagree with, while at the same time carried on the discussion you feel isn’t worth having, let’s keep it going.

Do you really believe we’ll wear out the friction brakes if they are used exclusively while we burn off the top 5% of battery capacity?

There’s wear every time something is used. Start the engine, use the friction brakes, roll down the window, push the Climate button. It’s an electric car that uses a gas engine to slow down. How is that clever? It’s turning clean energy into CO2. We make the car go with electricity and we stop it with gasoline. This doesn’t strike you as a flawed system?

Sure, it doesn’t happen frequently. It’s never actually happens to me in almost 2 years. The fact that it can happen, and that a group of engineers thought it was a good idea, is more than trivial and should be the topic of a lengthy discussion.

 

Nope - Not at all. My statement was that 'people' would squawk about brake pad wear. Personally, I don't feel it would be an issue, but my observations in the forum lead me to believe there are those who would take exception.

Nope - Not a flawed system... You haven't told me what you would do with this small amount of excess energy. Would you dump it to the friction brakes? If so I agree that would have been an acceptable solution. It is not "flawed" when another perfectly legitimate design trade was made by a group of very competent engineers !

You are making a mountain out of a mole-hill (my opinion). Your own words - "It’s never actually happens to me in almost 2 years"... My experience mirrors yours !!
It IS trivial, but if you want to perpetually debate something as insignificant as this, feel free. I have expressed my viewpoint, and I will allow others to debate this further if they desire. When I express my opinion that something does not warrant further discussion, that is my perspective. By no means am I trying to stifle a lively debate that others may want to continue with !!

As always, thanks for your perspective !!!

 

See my words below from this thread. I’ve voiced this before. Perhaps you missed it.

Maybe a qualified “flawed” would be more enlightening. Environmentally, ethically, morally, conceptually, etc flawed. Simply because something works doesn’t mean it isn’t flawed.

Thank you so much for granting permission to allow us to continue the conversation. I really would have felt terrible about myself if you hadn’t been so kind.

 

You're Welcome !

 

They could have done what they do on railroad locomotives for additional braking, called "dynamic braking" on the rails. The traction motors on the locomotive are switched over to become generators, like the traction motor on the Clarity, and that energy is fed to heating coils that create a huge load and thus lots for the motors to overcome.

Yeah, I know, what would be done with all the heat that would generate wherever on the car those coils would be placed?

 

If you're just dumping the heat somewhere it's like using the brakes and not much better than burning a little gas to somehow mysteriously use up the regen power the fully-charged battery is not able to accept.