Warm up?

I would REALLY like to hear from Toyota as to the reason that they seem to be so insistent about
warming up the gas engine. With my C, the cutoff speed is 10 MPH for the (limited) EV mode and it will not do EV at all after an extended cooling off period.......until after the "mandatory" warming up of the ICE.
I see no logical reason for this behavior.
Let the engine warm up WHEN IT IS FIRST NEEDED.

 

It happens because at speeds over 52km/h (32mph) your car enough potential energy to overcharge the already almost full cold battery if you hit full regen braking. So to protect the EV battery the computer starts the ICE to burn off some battery energy. If you keep it under 52km/h (32mph) and burn off some EV battery- you will be able to exceed the 52km/h (32mph) eventually.

 

Wait.....what ??
You can never gain BACK more charge via regen than you expended in getting up
to that speed......if the ICE is not running at all.
It is the first law of Thermodynamics, I think.

 

That was my point.
Don't start it unless and until it is really needed for something.
Just starting to warm it up incase it will be needed for something at
some unknown time and unknown reason in the future just
make no sense to me.

Then.....once you actually need to start it, let it warm up, sure.

 

Yes, going down a hill is a good example of possibility of overcharge to main battery.

Other thing is- that when you charge your car after work in the PM- and it's say 40f outside- the battery can take a full 100% charge at 40f so it does so when plugged in.
Now you go out to your car in the early AM and it's 18f outside. At 18f the battery can not take the same amount of charge as it did when it was 40f outside last evening. So you start driving and at the beginning of the trip before you get the chance to burn off a couple of EV miles you get up to say 50 mph and then have to stop for a red light- well at that speed and that low outside temperature the energy generated by the brakes would overcharge the main battery- so preemptively the computer starts the ICE to burn off some battery energy to avoid this situation.

 

The OP has a Plug-in-Prius just to be clear.
He's not starting it up- the computer is starting the ICE in cold temps as soon as he exceeds 32mph... just like it does with my PIP in cold temps to avoid overcharge conditions.

All the PIP's do this in cold temps when they have a full charge. One member here that lives on a hilltop actually only partially charges his PIP overnight so that when brake regen happens in the morning it's still below the "full charge" threshold that automatically fires up the ICE.

 

Maybe I misunderstood the situation and the question.
[edit] Maybe not. That makes even LESS sense. Why allow the battery to charge fully only to purposely waste some of it upon the next startup. I don't think I buy that, at least not "pre-emptively". [end edit]

With my C .....in Florida where it can't really be considered "cold"....the ICE starts EVERY morning, immediately; well after only a few seconds rolling back down the driveway and then it says "EV mode not available" if you push the EV button......AND after the engine is warm, it cuts off EV operation invoked with the button at 10 MPH.....EVEN though the hybrid logic can invoke EV up to about 35 MPH.

I got no problem turning on the ICE when you NEED to.......for ANY reason.
My problem is turning it on JUST to warm it up, when there is no other logical reason to
have it running. And then why cut off manual EV mode at 10 MPH, but that's another question.

 

o/p and easy rider, this has been covered extensively in many threads and the faq. many factors determine whether the pip starts the ice, not just speed and temp. it all makes sense when you understand it, it's not something toyota is going to change, it's a protective mechanism for the battery. if you want to understand it (to the extent that is possible) you have a lot of reading to do.

 

Easy Rider, if c behaves like gen2, you can't enter EV mode if you don't have enough charge. How many pips in your battery icon?

Manual EV was probably limited to 10 mph to extend battery life. C has less number of battery modules.

Back to topic, JEP is near freezing temp in Sweden. Battery cannot provide full 38kW at that temp. The available power would be around half. That's why you can't draw much amp before ICE running. I know, it would be nice if HSI bar adjust to it.

Fortunately, with Totque Pro app and custom PIDs, you see how much power hybrid system allow discharge/charge of the battery. That value changes depending on the temp and SOC.

 

Some factors in this discussion are fairly simple:
There are conditions that REQUIRE the ICE to run, a number of them.

If NONE of those conditions are present......which it seems that they are not for the C on the first start of the day, then there should be no reason to "blindly" start the ICE just to warm it up. Simple, at least in my view. Start it later
when one of the actual conditions requiring it actually occurs.

AND if the hybrid logic allows it to run in EV mode automatically up to ~ 35 MPH, there is no reason to NOT allow that to happen when EV is manually selected.......if no other factors enter in. It simply state something like: EV mode cancelled; going too fast.

AND.....there is some automatic protection for the battery from over charging or over discharging because the design only charges it up to 80 or 90% and only discharges it down to about 20%. The battery meter on the C actually shows that buffer. It may not on older models and it might be a recent convention for the Lithium batteries but I'm pretty sure it is a universally accepted standard now to only use the center 70-80% of the capacity. That gives longer battery life and gives a buffer for un-anticipated situations where that last 20% or so might be needed once in a great while.

It is possible that your car is set up that way but the battery meter is calibrated to show 100% when it is really 90 and 0% when it really is 20 or 10.

I don't consider this thread to be an argument........and don't want it to turn into one.
I KNOW I have a lot to learn; that's why I commented in the first place, to get some
additional information. Simply saying "You have a lot to learn" without providing some
references to accomplish that is kind of pointless.

 

understood, but you do come across as extremely frustrated over an issue most accept without too much problem. we might wish things were different, but we realize it is what it is.

 

There may be conditions you may not aware of. That doesn't mean they are not there.

Remember, the first priority for Prius is to reduce emission. Reducing fuel consumption is second. Prius must assume you can floor the accelerator at any time. It needs to get the catalyst converter hot enough to reduce emission.

You know if you will floor it or just want to move it out of the garage. That's why manual override EV button is provided to stop ICE from starting.

In hybrid mode, higher engine off speed may be allowed but power is limited to 10kW.

In EV mode, more power is allowed but speed is limited. It all comes down to battery life. The comprimise is better than no EV mode.

They are very good questions from your observations. I hope those answers shed some light.

 

That first part makes perfect sense. Issue closed.

The second thing about the battery, however, makes no sense at all.
If it REALLY is about battery life, the screen should say " Battery discharge rate too high" but it doesn't.
I've had it cancel the EV mode when coasting down a hill.......at 10 MPH.
And if the discharge rate is NOT too high when the system lets it to to 35 MPH for a half mile or so, what is the reason that having the button pushed is treated differently ??

Are you theorizing your answers......or do you have access to some "inside" information ??
Either is fine but it would be nice to know which it is.

 

or, they could emulate honda, showing 50 mpg epa when introducing, then 5 years later, detune the software to 45 mpg due to battery degradation and lawsuits.

 

My understanding is from my ownership experience with Gen2 and discussion on here since 2004 (boy, 10 years already). My observation also come from monitoring realtime data from Torque app with custom PIDs.

This is how the threshold is set:

HV Mode: Start ICE if 10 kw power or 35 mph is exceeded. For gen2, 42 mph. Gen3, 46 mph. This varies on region also. Europe has different thresholds.

EV Mode: Exit EV mode if 19.3 kW power or 10 mph is exceed.

If you want to roll downhill with ICE off up to 35 mph, switch the mode. Understand how it works and use it how it suits you. If you find anything on the contriary, pist here and we'll discuss.

 

32mph doesn't seem to be a fixed speed to me; after most of this winter in mine I'm fairly sure that it varies based on temperature and load requested from the battery. In very cold temperatures I can use only a very small amount of throttle before firing the ice until the battery has warmed up a bit.

At first it was frustrating, I've now come to understand it well enough that I can generally guess when the ice is likely to fire. As I'm still getting 65mpg on the tank I've been using during the coldest couple of months in recent memory, I'm happy enough.

 

You are right. Battery temp and its ability to discharge is also in the parameter.