Battery only above 42 MPH in 2007?

<div class='quotetop'>QUOTE(jharvey963 @ Dec 12 2006, 07:56 PM) [snapback]361179[/snapback]</div>

Yep,

You are right. You do not have a full understanding of the PSD (power sharing device) and or the terminology people are talking about on here. The MFD will display all battery drive above 41 mph, I have actually seen it pop in yellow arrows (battery) only as fast as 65 mph, in relatively flat Illinois here. That does not mean the car is in what is called on here "Warp Stealth". People with bigger hills see it jump into electric drive above 41 mph all the time, downhill.

Due to the PSD, which is a planetary gear set that interconnects in a clutchless manner, the engine, generator and motor (motor chain drives the final ratio gear set), the generator is overspeeded if the engine is not rotating, and the car is rolling faster than 41 mph. Warp Stealth is defined as when the engine is stationary , and in electric drive from I guess about 35 to 41 mph. Above 41 MPH one can get into an all-electric drive, but to do that the engine has to begin free-wheeling, to drop down the speed of the generator. There still is no gas being pumped into the engine, thus the yellow arrows, but its not too efficient, battery to drive wheels. Since the battery is driving the free-wheeling engine, too.

Regular stealth is when you pull out of a stop light at a slow rate in all electric mode.

 

It's a bit confusing.

The engine has to spin above 39MPG (I think that's the number) in order to keep the Power Split Device (PSD) from overspeeding. If you are coasting down a hill or are in any other condition that doesn't require much power above 39mph, the gas engine will be spinning even though most of the energy is being absorbed by the electric motor and used to charge the batteries. Because the gas engine isn't being given any fuel, the display shows it as not running.

This is my understanding of what's going on, anyone care to correct or elucidate?

 

That was a pretty good explanation, however, to be a little more specific, it's not the Power Split Device that runs the risk of overspeeding, it's actually MG1. It is limited to 10,000 RPM (in the HSD) so it has to spin the engine to keep it's rotational speed below that value. Normally MG1 is used to start the engine, but if the engine is not needed at that time, the computer doesn't send the engine any gas or spark. Since there is a conventional oil pump, all the engine components stay nice and lubricated.

This is a relatively unique situation, and more typically the engine would be running at the higher vehicle speeds.

 

<div class='quotetop'>QUOTE(8AA @ Dec 12 2006, 06:39 PM) [snapback]361208[/snapback]</div>

I've had an indication of Battery drive only at speeds of 75 MPH under downhill "trailing throttle" conditions. That is when the downhill slope is not steep enough to maintain the speed, so you are depressing the "gas" pedal to supply just enough power to keep from slowing down. I wasn't aware til this thread that the ICE was turning. I guess, with the way the planetary gears turn that MG1 would tend to overspin if the ICE weren't turning.

I don't think the Japanese designed the transmission. I think it came off of an alien spaceship

 

Just tonight I did a test for this before I read this post. Darell recommended trying this test out and it was pretty cool. Park safely near a freeway on ramp. I was in a shopping mall parking lot. While in a parking space, keep your left foot on the brake then put the car in gear, at the same time push the accelerator with your right foot. The battery will charge. When you have all green bars, check for traffic and when it is clear. Take your foot off the accelerator and start to drive normally on to the freeway. Get up to freeway speeds normally. Here in Houston the speed is 65 mph. Once up to speed you will see with all that extra power you can maintain speed with just yellow bars showing. I was able to go about a mile at 70 mph and showing 99.9 mpg during the test. Very cool. Thanks Darell! Now I can't wait for my PHEV conversion done.

 

Speed relationships can be seen in Graham's original nomograph at
http://ecrostech.com/prius/original/Unders...s/Nomograph.gif
6500 rpm is considered the limit in both NHW11 "classic" and NHW20
third-gen [commonly called "prius II"] even though MG1 was upgraded.
Note carefully that over reasonable engine RPM and road speeds, MG1
is the component that's going to be lashing back and forth most
wildly, and it is the limiting factor. Bringing the ICE on around
42 mph gives you a whole 'nother range to play in, in effect.
.
The difference you feel in your butt between fuel cut in high speed
[foot-off coasting or warp stealth] and injecting a little is *very*
subtle, and the MFD reads 99.9 in both cases so you can't go by that.
.
_H*

 

<div class='quotetop'>QUOTE(Cheap! @ Dec 13 2006, 01:52 PM) [snapback]361327[/snapback]</div>

When you were exceeding 42 mph, the ICE started and was running at about 1000 rpm consuming 1 cc of gasoline for about 2 sec to start your ICE.

Ken@Japan

 

WARNING WARNING WARNING!!!

THE PROCEDURE DESCRIBED BELOW CAN BURN OUT MG1, THE MAIN DRIVE MOTOR/GENERATOR!

<div class='quotetop'>QUOTE(Cheap! @ Dec 12 2006, 08:52 PM) [snapback]361327[/snapback]</div>

When you hold your foot on the brake and press the accelerator at the same time, current is being sent to MG1 to try to drive the car, but MG1 is not turning because it is linked to the wheels through a fixed reduction gear. This can burn out the motor. You will charge the battery, as described, but a full battery will do you no good if you fry MG1.

At the alternative fuel air in Lacey, WA, Frank Hudon showed us a burned-out motor from a Prius. He believed this was precisely how the owner managed to burn it out. (But that gave us the opportunity to see the motor and also the PSD, which was very interesting.)

 

<div class='quotetop'>QUOTE(daniel @ Dec 13 2006, 05:54 PM) [snapback]361913[/snapback]</div>

Thank you for that information. I won't try it agian! You probable just saved my MG1.