Interesting Reddit Discussion from r/Prius

You could try presenting some and see. It's funny, this isn't the first time you allude to having provided "much evidence", but one struggles to find in what posts you've actually presented any.

Little highlight from earlier:

To present evidence on which of two possible things happens when the battery charges too far to accept regen, your test has to continue to when the battery charges that far and one of the two things happens. Neither of your efforts from the summer did so, which is why they add no information one way or the other.

That shouldn't stop you from trying again, if you're serious.

If your efforts are received skeptically, they could be getting "completely ignored by those whose minds are firmly made up", or they could just be getting the expected scrutiny from other members with test data and instrument datalogs of their own.

 

The groundhog-day repetition in even just this one thread (of several!) is striking. Just last September:

There is precisely one participant, in this whole group of threads, who insists that others' tachometer RPM datalogs aren't evidence, suggests others are "just making things up" when they quote the owners' manual (with screenshots, no less)*, chooses to run 'tests' of his own that go nowhere near the 'goalposts' even when carefully advised beforehand where the goalposts have to be, then complains the "goal posts move around", then wants to "wait for the facts to resolve the issue."

Which the facts have done long ago for the others here who get in their cars and drive around and notice when the engine braking happens, and see it on their tachs when they have tachs.

Not to mention also for the others who routinely come to PriusChat and post questions wondering why their engines revved up when coasting downhill in D.

Sure, let's wait for the facts to resolve the issue.

* yeah, "It's not in the manual ... Are you just making things up?" happened, links are in here:

 

which year and model had that shifter?

 

A video to show what happens in D once the battery can accept no more regen would have to be made with that purpose in mind and have to ensure that moment is included in the video. Otherwise you're just trying to 'prove' something doesn't happen by posting a video in which it wouldn't have anyway.

No moving of goalposts here; that's been stated clearly going back months in these threads.

Now, one video in which something didn't happen is better than nothing, sure, but not much when you're showing it to people who own these cars and believe their lyin' eyes and ears when it does happen.

I could have made a video of this test back in 2023, if I'd had a passenger or phone mounts and wanted to fuss with it. Same for any of my road trips through mountains out east or west. But that thread didn't involve you and I had no expectation that anyone was going to say it wasn't 'evidence' if I just reported what was datalogged. That's kind of a unique you thing.

 

(As you already suspect) That's not a Prius. It's a current generation European Corolla Hybrid. (he even says it late in the video)

 

deleted reply to a deleted part of previous post

 

That still doesn't prove anything. Nobody is say the Prius ALWAYS uses engine braking in D. We are saying the Prius uses engine braking in D when certain conditions are met.

Those conditions are:
1. The HV battery is reaching or has reached max safe battery capacity
2. There is no pressure on the accelerator
3. The car would otherwise be accelerating(going downhill)

Those conditions were not met in the video, so I don't know what you think it proves.

 

Yep. You got me. lol

I thought twice about what I was saying and realized I couldn't prove it. So I deleted it while you were typing your reply.

I also watched the video closer and realized the needle was actually physical(though it still could have been digitally controlled) and it seemed to be registering RPM in B mode while the engine was not running.

I still stand by my point that it doesn't show what Paul thinks it does, but it doesn't show what I said it did either.

 

Strictly speaking, I'm not sure (3) is necessary; rather, the car is programmed to provide a certain resistance to forward motion when your foot is off the pedal. It provides that amount of resistance whether the car is pointed down or up or flat. When pointed up or flat, that resistance slows you. When pointed down, it may still slow you on a mild grade, or maintain your speed on a grade a bit steeper, or not maintain your speed on one steeper than that. The car's not doing anything complicated there, just applying one programmed amount of foot-off-pedal resistance regardless.

And in D, that programmed resistance will be supplied by regen for as long as the battery can accept it, and start to transition to engine at 77% battery (in a gen 3 HEV, anyway), fully to engine at 80% battery.

The reason you're more likely to catch it happening on a downgrade is because that's when the conditions can be satisfied longest. Pointed up or flat, the programmed amount of resistance will slow you down quickly enough that there's not much window of opportunity for the effect you want to observe. I think you'd still observe it, though, if you carefully created the preconditions and instrumented the test.

The car's behavior is nothing super sophisticated, just providing a certain programmed level of resistance to motion, using the choice of means it has available. What it avoids doing is having that level of resistance suddenly drop to zero when the battery fills up, which Paul expects, but which would be a lousy trick to play on unsuspecting drivers.

More important than (3), I'd say, to being able to observe the effect, is simple speed. The car is programmed to provide a certain force (torque) resisting forward motion, but the power that must be dissipated to do that rises linearly with speed. At lower speeds, you will barely hear the engine RPM needed to twirl off the small amount of power. At high speeds, you'll be one of the people posting "why does my engine howl when I back off the pedal?" questions.

 

Well, it'd be beating a dead horse if there were no new information appearing, but what has happened here is a little more interesting than that.

Notice that Paul has made a new claim, twice now in fact:

What's new here isn't that Paul thinks that's what happens; that's been the case all along. What's new is that Paul is now claiming to have observed it in testing: the battery became full, and at that point the resistance to forward motion changed to "no resistance at all" or "like being in neutral".

Notice that claim of actual observation is new for Paul. He's always expected it, and last summer there were two times he described intending to demonstrate it, but neither time worked out because he did not reach the battery-full precondition either time.

But now ... now Paul is telling us of some other test or tests, that can't be the ones he told us about before, in which he actually reached the battery-full threshold ... and actually observed the forward resistance drop to zero when it happened.

More details on those test(s) that we've not been told about before would be pretty interesting—not least because that's the exact outcome we repeatably do not observe when conducting the same test.

So there is a discrepancy in experimental outcomes to be explored here.

The repeatable experimental outcomes many of the rest of us have recorded, some with datalogs, have been offered to Paul, who dismisses them as not enough evidence.

And here is Paul, claiming to now have completed the same experiment with a contradictory outcome. Something to follow up on. However, while the evidence others of us have accumulated, including datalogs, are not enough for Paul, the evidence Paul provides from his own experiment(s) still seems to be ... less.