Owners manual for the 08 clearly states EV starts at 40 and below. I have already watched my tach bounce to zero just under 40 several times.

Cris

 

No. In reality the computer decides what to do based on efficiency or the charge state of the battery.

The computer tends to prefer to use the DC motor to handle initial acceleration (as long as it's gentle acceleration - if it's hard acceleration it'll use both motors simultaneously). Once it decides to swtich to combustion it'll usually use all combustion and no electric. That's good because combustion engines are least efficient when trying to accelerate -- but they're fairly efficient if all they have to do is maintain a constant speed on level ground.

If you need to accelerate a little faster (say the speed limit switched from 35 to 45 mph) then it'll still probably use just the combustion engine or maybe just a tiny boost from the electric. If you need to accelerate harder (say you need to pass another car) then it'll use both motors (which is how it gets performance that compares to the V6 Escape.)

Remember that all electricity in a car originated as gasoline. The hybrid just tries to capture the energy that other cars would waste (preferably as you brake).

 

All Ford Escape / Mariner Hybrids 2005-present are capable of driving with the gas engine off at any speed under 40 MPH.

It is difficult to reach 40 MPH when accelerating, but easy to have the engine kick off at 40 MPH when decelerating from a higher speed.

0-25 MPH is most typical, and that's what Ford published.
Also, I just learned there are old laws on the books in many states that say:
"An electric vehicle may not exceed 25 MPH on public roadways."
A hybrid is not a pure electric, but is Ford ( and others ) allowed to break these laws even if the law is obsolete? They might state "Zero to 25 MPH in electric only mode" just to keep some lawyers happy. -John

P.S. The motors are "AC" not DC. There is an inverter between them and the battery.

 

So are the 'EV vs conventional' settings user configurable? Maybe I can hack the firmware? lol

 

I would have to disagree GPSman, that is not what Ford published in my manual, nor is it how the 08 behaves.
The 08 FEH I test drove rarely started the ice under 40. It actually was almost predictably starting the ice just under 40, say around 38-39. I did lots of stops and go's in my neighborhood just to see how it behaved. This was under fair to light throttle. If I tried to take off "quickly" from any stop, it started the ice under 40 every time.
Just my observation when I drove the 08 FEH about 4 weeks ago.

I have also copied and pasted a quote from my 08FEH owners manual in pdf.

Conditions that
cause the engine to start up or remain running include:
• Driving request for moderate to rapid acceleration
• Vehicle speed above 40 mph (65 kph)
• Ascending a hill
• ECON mode not selected (while Climate Control is ON)
• Selection of climate control defrost mode or defrost/floor mode
• Charge level of high voltage battery is low
• Very high or low outside temperature (to provide system
cooling/heating)

 

My 08 FEH seems to selects EV or motor+ICE based on throttle position vs. speed. If i take off carefully, it stays in EV mode. If I make a fast or large change in throttle, it starts the ICE.

When I am working to hold it in EV, a curve will also start the ICE. (A curve causes + acceleration).

 

Sean, the 2008's are improved for sure, but what I stated IS how the 2008 behaves.
As you get faster and faster towards 40 MPH, the relative torque, and the relative power the electric motor alone can provide gets less and less.
It is a curve. As you approach 40 MPH, your chances of staying in EV get less and less. As a comparison, I can almost climb walls ( say a 25% slope ) at speeds of 15 MPH or less, as the torque at slow speeds is huge.
Ford's mass media campaign still cites "up to 25 MPH from electricity alone" even for the 2008 models. 40 MPH is the upper mechanical limit. It is impossible to go 41 MPH for example. But zero-25 mph is what 'most' drivers will see in every day driving. If you are reading this, then you are not a typical driver, and have learned, through practice and patience to get the full zero to 40 MPH in EV mode.
-John