Gliding in Neutral

The best example of the MFD being inaccurate is yesterday evening driving home from work. Cold and dark out side temp in the low 40’s. I start up the car drive 2 blocks to a streetlight that is typically a long wait. The engine temp at start up and after thermos dump is at 78 F now at the light it is up to 112 F. The MFD shows me stopped with ICE off but I can feel it and hear it. The RPM on the scan gage are ~1200 range and the car is warming its self up. Did I mention I turned the defrost on? I go through the light and get stopped at the next one. The coolant temp is now 147 F. The ICE is still running but MFD shows it off. I turn off the defrost and the ICE now stops and I can feel it shutter. I am sure most of us have had the same experience at one time or another. Having an independent monitor of systems is invaluable to learning about this complex car, not to mention fun!

 

To have any success in messing with neutral, you HAVE to be able
to tell when the engine is running. Because if it's already running
and you go to Neutral, it *STAYS* idling regardless of what you do
next, until you put it back into D. The only way neutral really
benefits gliding is if you're *sure* the engine has shut down prior
to you shifting to N. Which is why many people opt for the foot-
controlled glide, since in that state the MFD at least gives a
little more indication.
.
Neutral might give more benefit [at least in the way you were
thinking] in a conventional car, where the engine's always running
but keeping it down at dead idle might be better than leaving it
in gear at higher RPM even if the throttle's closed. Actually,
with many modern conventional cars it might not make much difference
since they tend to go to zero-injection "fuel-starve" when being
dragged along in gear anyways.
.
_H*

 

The ICE will go on if the battery gets to low. Been there done that.

 

I know this is an old thread but I thought I would add my experience with Neutral.

For me I found it difficult to glide, to put just the perfect amount of pressure on the pedal. I can do it for speeds below 40mph but not any higher. Tips are welcomed...

I use Neutral only under these conditions:

• There are no cars behind or beside me (just in case - I don't want to cause an accident)
• Only on a down grade
• Usually when I know I am coming to a point where I need to slow down anyway, like when I pull off to an exit.
• I always put the car back in gear when I am about to brake so I can capture some of the regenerative energy back into the battery.

I know there are a lot of recommendations on "not" using Neutral. From what I read, most people seem to think that using Neutral does not add the distance traveled to the MPG calculation. I can't disagree more. MPG will increase while using Neutral since the distance accumulated are still being added to the total miles - which changes the MPG.

Any tips on gliding above 40mpg are welcomed.

 

The ICE cannot re start in neutral. It will continue to idle if it is running when you go to neutral, but once in neutral it cannot start if it is not running no matter how low the HV battery gets. This is the one condition where the systems cannot look after themselves. The battery can be run so low particularly with the AC on that the battery will not have enough charge to start the ICE. The only cure after this is to have the HV battery charged at the dealers with a charger they have to order in from Toyota. There are I believe only two of these in the US.

John (Britprius)

 

Is it safe to roll at over 42 mph in neutral? Will MG1 still spin up the ICE in order to protect MG2 from overspeeding?

The PSD doesn't have a way to actually disconnect in N, right? Isn't it just kind of a simulated N that stops the energy flow?

 

No it is not safe. The MG's are disconnected electricaly in neutral so MG1 cannot spin or start the ICE. This means MG1 can be over sped (not MG2). MG2 is connected to the wheels of the car and spins at a fixed rate for a given road speed.

John (Britprius)

 

You are correct about the PSD not being able to disconnect, it also does not have a reverse gear. This is accomplished by reversing MG2.
Have a look at the link below and play with the sliders to get a good understanding of how it all works.
Toyota Prius - Power Split Device

John (Britprius)

 

haha--I was just playing with that simulator when I saw your last post.

I guess since if the ICE is spinning when N is activated, it will continue to spin so the only danger is entering N without the ICE spinning and then rolling downhill to past 42 mph.

Hmm, according to the simulator, max speed in reverse is 25 mph?...

Thanks for the clarification.

 

The ICE will continue running if it was running when shifting to neutral, but when it gets up to temperature it will shut off it then cannot restart. This obviously still makes it dangerous to be in neutral above 41 mph.

John (Britprius)