High speed in N (and ICE @ 0 RPM)

He should try shifting back into D to see if it'll even start the ICE at that speed...

Anyway, if hes applying the brakes to slow back down in neutral, hes wasting more energy then hes saving by going ice-off.

 

He will eventually destroy MG1. There is obviously a "safety margin" built in, otherwise he would have already heard a terrible crunching sound as MG1 destroyed itself and the rest of the HSD. But if he keeps doing it the MG will eventually disintegrate, taking out the rest of the drive system with pieces flying/floating around in there.

Isn't coasting in N downhill illegal in Italy? It is here in North America. I don't understand why anyone would do it. Too lazy to use the accelerator pedal to find "hyper stealth"? He -may- have saved a few euros in fuel. He -may- do about 3000 euros in damage real soon now.

 

I agree that that's a heck of a hill, because I think the most
I've ever touched in warp-neutral is 68, maybe 70 MPH by which
time both air-resistance against the car and the windage from
the MG1 rotor screaming around a touch over 10K RPM were exerting
significant retarding force on the vehicle! MG1 is likely good
for shortish bursts of that sort of speed; you wouldn't want to
spin it that fast all the time, and it would be almost impossible
to do so. But in random experiments with engine-out conditions
I've made the butt-dyno determination that over 50 or 55 MPH,
warp-stealth [spinning the engine too] is less drag on the car.
.
_H*

 

Tell him that his action re-inforces unfortunate stereotypes of Italians and machinery :_>

 

Nothing will happen, by driving the car in neutral while going down a hill no matter how fast you go. I don’t know why everyone keeps getting this wrong. I have posted this information in the past and everyone keeps getting it wrong, still. Its like an urban legend.

The computer software is designed to take care of the car to prevent it from being destroyed. It is all written up in the 2004 Prius New Car document.

What is dumb about going down the hill in neutral is that you don’t regain any energy to charge the HD battery, because it shuts off all the output transistors that would normally charge the HD battery. So the SOC of the HD battery just decreases going down the hill.

The software will take it out of neutral automatically, without you knowing, under the following conditions:

1. When breaking: it takes the car out of neutral. This is hidden from you and the car as far as you are concerned is still in neutral.

2. When the speed of the car gets too fast it tuns on the engine to prevent MG1 from over revving.

There is another reason, but I can’t remember right now.

 

I was not wrong before either. I am not making this up. Here is a direct quote from the Toyota documentation. Look it up yourself:

On Page TH-5 (3. Hybrid Tansaxle)

Clutch-Less System

A clutch-less system has been adopted to mechanically link the front wheels and MG2 via gears and a chain. To disengage the motive force in the neutral position, the shift position sensor outputs an N position signal to turn OFF all the power transistors in the inverter (which connects MG1 and MG2). As a result, the operation of MG1 and MG2 shuts down, thus rendering the motive force at the wheels to zero. In this state, even if MG1 is rotated by the engine or MG2 is rotated by the drive wheels, no generation of electricity occurs because both MG1 and MG2 are inactive. As a result, the SOC (state of charge) of the HV battery decreases as the shift position remains in the “N†position.

On Page TH-46 (3. HV ECU Control)

Shut Down Control

Generally, MG1 and MG2 are shut down when the shift position is in the “N†position. This is because MG1 and MG2 must be stopped electrically as a means of shutting down the motive force, since MG2 is mechanically joined to the front wheels. However, the shut down function is canceled under the following exceptions:

· During driving, if the brake pedal is depressed and a wheel lock up, the ABS with EBD is activated. After rotation of the wheel. Even if the shift position is in the “N†position at this time, the shut down function is canceled to allow the wheel to rotate. After the wheel rotation has been restarted, the system resumes its shut down function.

· When the vehicle is driven in the “D†or “B†position and the brake pedal is depressed, the regenerative brake operates. At this time, as the driver moves the shift position to the “N†position, the brake hydraulic pressure increases while the request torque of the regenerative brake decreases gradually so as not to create a sluggish brake feel. After this, the system effects the shut down function.

· When MG1 and MG2 operate at higher speed than the specified level, the shut down function is canceled.

 

Hi Rolf,

Regarding #1 above: the car is taken out of neutral only to the extent that a wheel has locked up. If no wheel is slipping, then the system will return to N. See the last sentence of the first bulleted text in your quote below.

Regarding #2 above: I ask that the contributors to this string read the last bulleted text below.

Does anyone have instrumentation that shows MG1 RPM? If yes, has that individual allowed MG1 RPM to exceed 11K to see what would happen? (I had the Ecrostech scanner for my 2001 which did show MG1 RPM, but at that time I did not have the idea to put the car in N at high speeds...)

 

Hi Evan,

OK, if the MG1 speed limit is supposed to be 6K RPM and you got MG1 above 10K RPM, then it would appear that the NCF text is not correct. This wouldn't be the first time that the text was found to be inaccurate...

 

if what u say is true, why can t the Prius be towed?

it specifically states you must flatbed it