I know that I can't tow the car w/ all wheels on the ground, but can I coast in neutral when going down a hill, etc. w/o damaging the vehicle?

What cars do and do not have issues with the coasting in neutral trick?

 

NO NO NO NO

Coasting in neutral is not only dangerous, but illegal in many states.

If you want to save a few pennies in gas, try car pooling, bike riding, taking mass transit or walking.

Please don't consider this silly stunt to squeeze a few extra miles out of a gallon of gas.

It is dangerous and illegal (and could cause damage to your car)

 

I have a lot of backroads w/ no traffic. That's where I was talking about and since the brakes and power steering are electric, those are unaffected. I would NEVER do that with traffic around. BTW, shutting off the engine in these things is really dumb (tried it once, again, with zero traffic on a little traveled backroad). Holding the stop/start button for 3 seconds turns off the engine and the car is pretty useless. You CANNOT restart until you come to a stop and place it in park. You cannot resume/restart in neutral or any other gear for that matter. So, turning it off is dumb.

Anyway, just thought I'd ask. I was more concerned about mechanical damage than anything else. I have zero pts on my license and my last speeding ticket was in 1995....so I'm not some reckless tard. I put safety first.

Mark

 

I seem to recall that there was at least one (maybe more) thread in this forum on the topic. If memory serves me, the general concensus was that it does increase the risk of damage to the car (althouth I'm not a mechanic).
Try this thread

 

You do realize that coasting in neutral contributes to depletion of the traction battery. There is NO way to charge the traction battery when in neutral. It's the design of the system.
So all electrical accessories, DRL's etc. even though they are 12 volt ultimately are powered by the traction battery via the inverter to recharge the 12 volt battery.
So when you stop coasting an get out of neutral you'll just have to replace that energy at a cost.

It's like the Fram Oil commercials... Pay me now or pay me later.

Personally, regenerative braking without actually pressing the brake pedal at least somewhat is just about NIL. I notice very little deceleration difference leaving it in "gear" as opposed to neutral.
The safety/legality issues have been address previously.

 

Ok...sounds good and also sounds like the risk and other items don't make it worth it. So, does the 12v battery charge from the HSD system and not an alternator? I haven't looked, but that does make sense. Regen w/o hitting the brake takes forever to do any sort of charging, so I'm in agreement there...it's that quest for a bit more that made me ask. Now, the regen, how does that work exactly (I know the electrical part on electricity generation) in terms of where does the electricity get generated, how much, does it change with pushing the brake pedal, does it increase with a harder push on the brake pedal, and finally, how much of the braking is the regen and how much is the braking system when a normal stop is done? I did notice that when you hit the brake and just before you trigger the lights, it increases drag and makes that mechanical "I'm generating electricity sound" :-)

 

The concern regarding "neutral" (in quotes as there really is NO neutral in these cars) is the following:

You start on a downgrade in "stealth" mode (ICE off) somewhere under 42 miles per hour. As you pass 42 MPH the ICE will not start. Without the ICE running MG1 will eventually overspeed.

As a practical matter you would have to be on quite a steep and long downhill grade. And you would have to go well over 42 to overspeed MG1. (I'm sure there is a lot of margin in the design).


One thing to consider on the TCH (vs the Prius) is that the arrows showing battery flow are "more sensitive" than those on the Prius. So while people "glide" in the Prius without arrows there really is a bit of current running into or out of the battery. The TCH simply shows these lower levels of current.

To glide, teach your foot to makes the arrows just disappear or reverse direction. If you don't move your foot you are hardly drawing or regenerating any current. With a little practice this is easier than shifting into and out of "neutral".


As for this being a "dangerous stunt" let's get a grip. The reasoning behind the no "neutral" laws dates back to the Model T. Cars back then had no brakes to speak of. So going downhill in neutral was dangerous as the brakes couldn't stop the car. With the advent of disc brakes 40 years ago this is no longer a problem (unless you are descending Pikes peak or Mount Washington).

 

This brings up a good question...I'm a tard and I'm sure this is in the faq, but at 230am, I'm going to ask anyway. What does MG1 stand for (I'm assuming this is the electric motor/generator) and what does an overspeed condition do? I'm not doing the neutral thing, but just making sure I have things straight. That making the arrows disappear is VERY hard on the TCH. However, leaving the drain from the battery going and having it minimal did the best.

Also, what if the ICE is still running when you are in neutral? Is there a risk of overspeed then?

Thanks,

Mark

 

Another situation that might come up (under rare situations) is the need for an emergency evasive maneuver (if you ever find yourself in the Delta Quadrant). I can't describe when this scenario would occur, but let's assume you are gliding along and need to have both hands on the wheel to swerve and you need to accelerate (again, it seems like an unlikely situation). The action of taking the hand off the wheel to put the car in gear creates a potentially dangerous situation.
I guess, the rule of thumb is, what would you tell a teen aged child to do?
Let's assume one has a teen ager and you are taking them out for driving lessons. Would you say, "put it in neutral when you are on the highway" or would you say "keep your hands on the wheel, pay attention to the road and don't play around with the gears"?
Yes, the advice is overly simplistic, but how much money is someone going to save by putting it in neutral? $5/year? $10/year?
Why take a chance?

 

mlarma — If the ICE is not rotating, the relation between the road speed RS and the speed Ns [rpm] of MG1 (Motor-Generator 1) is:

Ns = -73.37 RS [for RS in km/h] = -118.08 RS [for RS in miles per hour]

(See the thread "Heretical Mode" for more information.) At the car's governor-limited top speed of 185 km/h (~116 miles per hour), this means that MG1's speed would be ~-13 573 rpm. The MGs are rated by Toyota up to 14 000 rpm. So from this point of view, things seem to be safe. But in 'N' the freely spinning MG generates a high open-circuit back-EMF voltage, which can cause electrical breakdown and failure of the electronics module under these conditions (which would also apply to "wheels-down" towing in 'N'). This is probably the more relevant concern about coasting at speed in 'N.'

When the ICE is spinning at speed Ne [rpm] say, the relevant formula is:

Ns = 3.60 Ne -73.37 RS [for RS in km/h] = 3.60 Ne -118.08 RS [for RS in miles per hour]

One can see that the speed Ns of MG1 is reduced to safe levels when the ICE is running at idling speed (~1000 rpm) or faster. Normally, when not in 'N,' the ICE is being spun at ~1000 rpm (in "fuel-cut" mode) whenever the car's speed exceeds ~64 km/h (~40 miles per hour) to offer this protection.

I agree coasting at speed in 'N' is not a good idea.

Stan