The computer decides when to start the ICE based on probably dozens of parameters, of which you have control of only two (speed & gas pedal position). After a lot of experience you can get an idea of how to encourage E mode as much as possible, but even if you perform the exact same inputs (ie speed and gas pedal) two times in a row the TCH may do something different simply because it is considering far more parameters then just what you are doing.

Keep in mind that the ICE will run (or at least rotate) at all speeds above 65kph. It is physically impossible to exceed this speed without the ICE turning due to the way the ICE, generator (MG1), and electric motor (MG2) are inter-connected thru the power split device (CVT tranny). It is still possible to run on battery alone above these speeds (usually downhill or with a tail wind), but the instant FE gauge will register 0L/100km instead of "E" because the ICE is spinning but using no fuel.

There are two camps, one that says encouraging E mode is counter productive to maximum FE because of energy conversion lossed involved with charging then using the battery and the other that believes using E mode as much as possible yields best FE. I personally lean towards maximizing E mode because in practical experience when I don't my FE gets worse, but I think the true answer lies in the nature of each owner's daily driving conditions.

 

haha...

Well if the catalytic converter is still cold, it won't go into glide.


I don't like my battery dropping lower than 5 bars. It seems to be yielding good results (by staying out of EV and gliding instead since gliding is a "free" ride while EV has greater battery drain). I'm getting at least 0.5L/100km (even up to 1L/100km) than the "average" driver in my area.

 

Please note that the no arrow gliding is not "free".
It consumes 3A to 7A HV battery discharge current.
http://priuschat.com/index.php?showtopic=34344&st=2

Ken@Japan

 

I know, that's why I have quotes around the word free. I think it was Evan at PC that told us how many amps it was drawing.

 

I agree with this. We have hills where we live, and when we're on a flat or a slight downhill, I'll maximize the coast, under 40mph so the ICE doesn't turn on, and very slightly push on the gas to maintain a little electric power. If the ICE turns on or I start to slow down, I'll "pulse" to a higher speed and then "glide" down to the speed I want.

In terms of recharging the battery, since we have hills, the battery will be charged when I'm either coasting downhill and not going on the gas, or when I have to actually turn on the ICE uphill.

Interestingly, after I gave my wife the car, I pointed her to the "pulse and glide" explanation websites which she had no patience to read, but she ended up figuring out the technique on her own and gets way better milage than I ever did when I drove it (she's hovering between 38-40).

Benny

 

benny — You can't fairly assess fuel efficiency using only partial or one-way trips. For meaningful results, it's necessary to look at FE on round-trips only, so that hills are traversed both up and down, and the car ends up at the same altitude that it starts at. It's also necessary that the NiMH battery should be charged to the same level at the end as at the beginning of the trip. Give us some FE data from just such trips please! I'm afraid that (as mentioned by Droid13 in Post #11) I'm one of the people questioning the common "wisdom" that maximizing EV-mode maximizes FE. No-one has yet provided data to refute my claims, whereas I have provided data that supports them. Have a look at the thread "An Unpalatable Fact (with apologies to Al Gore!)."

By the way, I agree with almost everything that Droid13 has said in his excellent posts in this thread!

Stan

 

Well SPL... I have the same believes also. That is why I am questioning the TCH design/computer program. The gas paddle seems too sensitive, the slightest acceleration will trigger the ICE to come on instead of pushing it in the EV-mode.

ACE

 

Ace — As Droid13 said, the ICE probably comes on because the Toyota computer system believes that, at that moment, this is the most efficient way to provide you with the power that you are requesting. I'm puzzled because, if you do agree with me, then why are you trying to over-ride the TCH's ECU and force as much EV-mode operation as possible? My belief is that this is, in general, counter-productive, and will likely lower your FE.

Stan

 

The difference is that if you are forcing ev mode, you MIGHT, and I stress MIGHT, be driving in a generally more fuel efficient manner and the savings are not coming from the EV mode vs ICE running, but the manner in which you are driving.

I was going to collect data, but in my normal commute, there proved to be way too many factors affecting mileage (the biggest was wind) so I could not get any meaningfull data. One day I would have 20 + MPH head wind, the next a quarting wind the next a tail wind, the next... nothing I felt gave a good fair representation. I also felt my commute had too much highway driving to actually test the Ev possibility. You need more transition period driving (35 - 45 MPH) to be able to have a good EV vs ICE data collection set.

 

That's the essence of it. I think SPL and I agree on what's going under the hood and the "potential" for extended use of battery alone to be counter productive. The reason I stay in the pro-EV camp is that I still believe it is a very low power consumption state for the car to be in and adapting your driving style to maximize low power consumption states is a good thing.

That said, I certainly don't go overboard by using EV at every possible opportunity. I tend not to use it for accelerating as ACE suggested except if I know my accel. will be short (upcoming traffic, lights, stop, etc.) but I will usually operate the gas pedal in such a way to always try to "encourage" the TCH to spend more time cruising or coasting in EV when practical even if it means giving up speed gradually when appropriate. And I do recognize that ultimately the car is more efficient at cruising speeds above EV so I don't deliberately drive extra slow just to stay in EV (and possibly some efficient battery charging happens here ).

Is there a point at which you can overdo it, probably. This is the dividing line between SPL and myself, but finding that line will be very tough. SPL has shared with us a lot of very cool mathematical simulations of power requirements at various fixed speeds and energy costs from battery charging, etc. I can't argue the math (I usually have to read it 3 times to understand it ) but I recognize that there are significantly more variables that the HSD is dealing with in making its logic decisions concerning ICE vs EV. Even doing physical testing will be tough to control the variables and collect fully accurate data. I'm putting with faith 11 of my 12 eggs in the basket that says the logic control will be charging the battery with better efficiency than I'd get otherwise, after all thats what the hybrid concept is all about. How I would love to see the code that makes these decisions.