I just started to notice how well my 08 FEH AWD does at holding its location when stopped at a red light going uphill. We have a few hills - not large ones - and if I'm stopped going uphill - I can take my foot off the brake and the car never rolls backwards. Its held its own on every hill I've tried. My other automatics will hold the car if the hill is slight but not on the ones the escape holds.

 

i believe suburu had this feature a while back where the brakes actually stayed on until movement was detected. could this be what is being done here?

 

What you are experiencing is creep-mode. So that the car feels like a normal car, the electric motors are programmed to ease the car forward at a very slow speed - much like any automatic tranny car would do. But, doing this costs you battery power. If you put the brakes on you turn creep mode off and will save you battery power and thus, gas.

It probably isn't good for the motors either to use them to hold hills.

 

Why not? I can't think of any reasons. The system is putting X amount of current through the motor. It doesn't matter if the rotor is spinning or not.

Of course this assumes that X is less than the max sustainable current, but we already know it is.

 

This creep in mode must have to learn how to work, within the first 100 miles of having my vehicle, I almost rolled backwards into someone on a moderate incline when switching from the brakes to the gas.

I actually went out and tested it for awhile on other inclines because Ford was going to fix this problem. I called the dealer, and they said to wait till the first tank of gas was gone, and then the problem would go away.

I havnt noticed it since.

 

I don't know, maybe it isn't BAD for them but maybe it isn't good for them either. There is a reason it is disabled when you have your foot on the brakes.

Many electric motors get cooling air when they spin. You would be generating heat by using X amount of current and heat certainly isn't the friend of electric motors.

Or maybe I just wanted to see how long it would take someone to say I was wrong?

So, your choice I guess. Put the brakes on and disable the creep mode and save some gas in the process or sit there and let your electric motor hold you on the hill.

 

This is addressed in a Ford patent:
Torque control strategy for management of rollback in a wheeled vehicle whose powertrain includes a rotary electric machine


http://www.freepatentsonline.com/6321144.html

GaryG

 

Be careful of this.

If you touch the brake VERY gently, it will make electrical contact with the brake sensor, but NO contact with the regular contact brakes.

This in effect, puts the car in "neutral" and you will roll back.

This is called "deadband" by some people, and is desired ( in forward ) those times you wish to coast for good MPG.

Same effect happens with a very gentle gas pedal press.