ICE runs after going down a hill at the beginning of my drive.

I finally decided to open my own ticket complaining about ICE turning on randomly after topping off and the failures to activate hondalink. Let's see if these problems will continue falling on deaf ears.

 

Thank you. We need to stick together on this issue. Flood Honda with tickets.

 

The ICE coming on at full charge/battery is something that also occured with the NSX hybrid system and happened much more frequently due to the small battery in that car.

Albeit annoying, it's not out of the ordinary and highly doubtful Honda is going to change anything to "fix" a non-issue.

 

Yup. If indeed Honda has engineered the Clarity PHEV to at least occasionally turn on the ICEgine as part of a system check to see if everything is working okay, as some have suggested, then from Honda's viewpoint it's neither a malfunction nor a "problem", and thus nothing that needs to be fixed.

As has been pointed out, there is no "EV mode" in the Clarity PHEV. There is an "Econ mode", which does not imply any promise that the car will run 100% in EV mode.

​

 

Guys, Bob is not complaining that his ICE comes on. We all know it’s a PHEV and not a BEV and p 13 of the manual gives us 5 scenarios where it will come on.
Bob is complaining that his ICE is coming on excessively. And certainly his posted experiences are very atypical compared to the rest of us.

 

My apologies for not reading more of this thread before posting a comment.

Can you explain the issue with the ICEngine starting when someone starts his trip at the top of a hill? I guess I missed something in the conversation.

I can understand why the car would limit regen under that circumstance, but not why it would turn on the ICE.

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There has been much speculation on this in several threads, but the bottom line is no one can say for sure. We can say that it’s happening often enough and to enough of us to call it a real event. It appears that somehow the traction motor, starter generator, and ICE In some combination are called upon for braking when the HV battery is completely full (allowed useful capacity) and the algorithm limits the amount of regen normally allowed. The prevailing and reasonable assumption is that this is to protect the HV battery from overcharging past the limit set by Honda. It doesn’t happen all the time and the additional triggering events are not understood either.

The Clarity Brain Trust has postulated several reasons how this might work and several reasons why it can’t possibly work. So it’s kind of like the bumble bee. Everyone knows it can fly, but until recently nobody could explain how.
What we all wouldn’t give to have some Honda engineers sit down and explain it all to us.

 

Now that it has been reported in another thread that regen can achieve an EV range readout of 84.5 miles, I'm totally at a loss as to what constitutes a fully-charged Clarity battery, and even more puzzled why the Clarity would start its engine soon after starting a trip with an EV range readout of way less than 84.5 miles.

I guess the 84.5 mile range isn't actually how far the Clarity could go on EV power.

 

So far Honda is in denial. I have said this a few times. All who are experienced being ICEd need to open a ticket with Honda. If they get enough, perhaps they will pay attention to it. Apple does this with bug reporting. I get feedback from Apple when engineers need more info. So, Apple is paying attention.

 

Bob, I wish you the best but you
are in a very, very, very small minority of Charity owners with this problem so you will have a hard time getting enough tickets made on this for Honda to notice like on the HV Range fix.

 

It doesn’t matter how few owners have the issue. They need to report it.

 

I guess the following has already been theorized, right? EV cars emulate engine break by regen. If the battery is 100% full and so does not accept any regen, there are 4 options:

1-Skip engine break. Act like the gear is N
2-Dissipate the regen by passing it thru a large resistor
3-Lightly apply the breaks
4-Start the engine

It looks like Honda is doing the 4th, which is the easiest and least expensive. Maybe #1 is not done for safety reasons. #2 and #3 might be engineering nightmare.

So what does pure-EVs do for this? Anyone knows? I have been driving a Leaf for 5+ years and don't know that. I bet it is #1 though.

 

We had Leaf for 7 years. Would like to know how regen is handled with full battery. Unless it is never fully charged.

 

1-People need a way to perform pseudo engine braking. You wouldn't to use brakes all the way down a mountain.
2-A very large resistor that would be difficult to find a good location for in the car
3-Again, you wouldn't to use brakes all the way down a mountain.
4-When the engine is running, it's producing electricity. I'm unclear how it could dissipate electricity.

The to achieve pseudo engine braking, the Accord Hybrid cuts off the fuel to the engine and uses the starter motor/generator to spin the unfueled engine. The compression of the engine provides resistance to use up the excess electricity. No one has reported this happening in their Clarity PHEV.

 

How much battery is used in driving .3 miles? How much is generated by braking? Hard to believe that braking would generate.3 miles worth of battery capacity. Why doesn’t ICE come online immediately on first braking?

 

Perhaps this is nit-picking, but an EV's regenerative braking literally is engine braking... or to be more precise, motor braking.

#GrammarNazi

Or...

5. Turn regen to 0%, turn normal (friction) braking to 100%, no need to start the engine.

Seems that should be the simplest and most efficient way to handle it. Apparently Honda's engineers don't agree.

Also...

I'm not seeing how starting the ICEngine would in any way affect how much or how little energy is generated by the electric motor being used as a generator, in regenerative braking mode; nor affect the ability of the battery pack to absorb that energy when it's full.

Turning on the ICEngine in response to the battery being full is, for this armchair engineer, nothing short of bizarre. No doubt Honda's engineers can explain why; no doubt the situation is much more complex than my limited understanding. But it leaves me utterly baffled.

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I think of a coffee urn that holds 30 cups of coffee. Open the spigot. Coffee runs out rapidly. Take off the top and use an eye dropper to fill the urn. That is what it seems to me how the battery is used to propel the Clarity, while the regen is refiling the urn. In the Leaf we had, there were 12 bars indicating how much charge was left in the battery. No matter how much regen there was, even an extended downhill run, the bars never went back up after being depleted. In other words, no amount of regen can charge the battery as quickly as a 240v or even a 120v source. Further, the last 20% of charging takes much longer than the first 80%. Presumably this is a safety measure to keep the batteries from overheating and perhaps exploding. And, why does the ICE sometimes come online at first brake application, but sometimes not?

 

My apologies Bob. Didn't know the ICE coming on was excessive, beyond it kicking in when battery is full. Either you've got something wrong or the battery in your car is kept topped off all of the time.

Speaking of topping off batteries. We took a little 250 road trip today which allowed for some experimenting. In HV mode at freeway speeds, the computer would not allow any regen to occur after about ~35 miles of EV range when attempting to charge further in parallel HV mode (part throttle). It would keep kicking the car into EV mode via a small section of blue bar (to about 11 o'clock) in the power gauge. Perhaps it is the computer's way of forcing battery discharge?

 

In the following graph, you can see that the Clarity PHEV intermittently activates EV drive mode when cruising. Honda's engineers have determined that's the most efficient way to propel the car.

 

Bob: I saw our leaf gaining 2% battery charge in a matter of 30-40 seconds when going down a steep hill (those who know Austin, it is the end of the Jester road). But of course I was breaking heavily.

Does the engine turn on also when the battery is not 100% full? Like 50%? You probably answered this on your other thread but I am too lazy to search for it :-(.

My house is at the top of a steep hill, but that direction goes to a dead end so I never took that direction. Let me try to go that direction today.