CC, full charge on Battery and compression braking down a steep grade.

[OneSpeed]

I took the FFH over the Grape Vine today. Going up the hill the car was outstanding. I hate not having a tep gauge but oh well. On the way down the grade before the battery got charged to the max, I had cruise control on and the engine compression braked like it has done before on much smaller grades. Then I noticed that the Battery must have fully charged because I no more battery current indicator showing power going in the Battery. Then I noticed that the engine no longer compression braked to slow the car, the electric motor was now used to slow the car. The charge indicator was discharging as if the motor was powering the car.

[hybridbear]

Then I noticed that the engine no longer compression braked to slow the car, the electric motor was now used to slow the car. The charge indicator was discharging as if the motor was powering the car.

I think the motor was powering the car. One thing I've found when driving on hills is that our eyes and brain are a very poor judge of elevation and road slope. I found many times when we were in Cali a few years ago on vacation that the road looked to be going down but the way the car behaved told me that we were climbing.

[md13ffhguy]

I have noticed that the cruise control works very differently between the standard CC in my wife's 2014 and the adaptive CC in my 2013. Going downhill in the car with ACC, the set speed is essentially maintained, however, with standard CC, the car tends to run away, picking up a significant amount over the speed limit on some downhills.

[md13ffhguy]

OneSpeed, have you tried engaging the grade assist on downhills?

[corncobs]

OneSpeed, have you tried engaging the grade assist on downhills?

This will offset some of the runaway once the HVB can't take anymore charge.

[Hybrider]

... I hate not having a tep gauge but oh well...

 

You can have the temperature gauge displayed as one of the options in the MyView screen, in the left hand display.

[mwr]

I have noticed that the cruise control works very differently between the standard CC in my wife's 2014 and the adaptive CC in my 2013. Going downhill in the car with ACC, the set speed is essentially maintained, however, with standard CC, the car tends to run away, picking up a significant amount over the speed limit on some downhills.

My 2015 using standard CC behaves just the opposite. It maintains the set speed going downhill.

[OneSpeed]

My 2015 using standard CC behaves just the opposite. It maintains the set speed going downhill.

I think you may have misunderstood, the did maintain a constant speed at were I set the Cruise Control. At first the engine was used to slow the car and maintain the set speed going down the grade. Then the HVB reached a full charge, the car took a different technique to maintain down hill speed=it used the electric motor to slow the car not the engine. I could see this by the way the HVB started to show the discharge arrow as if the motor were driving the car. Basically the motor was running as a type of brake.

[OneSpeed]

 

You can have the temperature gauge displayed as one of the options in the MyView screen, in the left hand display.

How? I thought I looked through all of the options, no Temp, no Tach?

[Easy Rider]

Mine has adaptive cruise and grade assist.

 

The first time I engaged grade assist, it was AFTER I was already speeding down the mountain.

It worked but the transition was rather unsettling, with some jerking and roaring.

 

Next time I engaged the grade assist as soon as I saw the warning signs and it worked extremely good along with the cruise.

Smooth and steady, with a sound from the engine not unlike downshifting a conventional car.

[OneSpeed]

This will offset some of the runaway once the HVB can't take anymore charge.

No, that never crossed my mind. I will try it today going over it again.

[Texasota]

How? I thought I looked through all of the options, no Temp, no Tach?

You can have two functions displayed in the "My View" display. I have the tachometer and the temperature gauge configured.

 

From page 97 of the 2015 Owner's Manual:

 

 

MyView

You can choose what to display in this view. Selecting Change MyView in the options menu allows you to scroll through two columns of content choices.

• Press the up or down arrow to view content.

• Press OK to save your selected content.

• You must select content in both columns before you can save your new MyView.

Edited December 24, 2014 by Texasota

[Hybrider]

And on page 95 of the 2015 Fusion Hybrid OM, it lists the available options for the MyView selections.

 

[OneSpeed]

You can have two functions displayed in the "My View" display. I have the tachometer and the temperature gauge configured.

 

From page 97 of the 2015 Owner's Manual:

 

Got it done thanks.

[hybridbear]

I think you may have misunderstood, the did maintain a constant speed at were I set the Cruise Control. At first the engine was used to slow the car and maintain the set speed going down the grade. Then the HVB reached a full charge, the car took a different technique to maintain down hill speed=it used the electric motor to slow the car not the engine. I could see this by the way the HVB started to show the discharge arrow as if the motor were driving the car. Basically the motor was running as a type of brake.

The motor can't be used to brake. You must have been going uphill or on flat ground at that point.

 

When descending a steep grade the car tries to store all the energy in the HVB first. The charge limit is 35 kW which isn't a lot when you have a heavy vehicle moving at high speed down a grade. Thus, the ICE will come on with no fuel being injected to work as an air pump to burn off the excess energy. The electric motors don't have a method to slow the car down other than charging the battery. The traction motor consumes electrical energy to power the vehicle in EV mode and the generator motor consumes electrical energy to start the ICE.

[OneSpeed]

The motor can't be used to brake. You must have been going uphill or on flat ground at that point.

 

When descending a steep grade the car tries to store all the energy in the HVB first. The charge limit is 35 kW which isn't a lot when you have a heavy vehicle moving at high speed down a grade. Thus, the ICE will come on with no fuel being injected to work as an air pump to burn off the excess energy. The electric motors don't have a method to slow the car down other than charging the battery. The traction motor consumes electrical energy to power the vehicle in EV mode and the generator motor consumes electrical energy to start the ICE.

Do you know this as fact, or just a hunch? I am sure the electric motor was not driving the car to speed up down hill.

I used the Down Hill assist, and it seemed to work the same with or without it. The engine compression braked in both mods and the speed was maintained where it was set in CC.

[hybridbear]

I am sure the electric motor was not driving the car to speed up down hill.

I agree. My guess is that what you perceived as downhill was actually uphill. As I stated before, this is very easy to do. Thus the electric motor was powering the car & the HVB was discharging.

 

It's very easy to misjudge this, particularly at night. Read this scientific study for more info: http://www.sciencedirect.com/science/article/pii/S0042698904004511

 

Basically the gist is that while our eyes & brain are perfectly designed, we can't always believe everything we see since perception plays a big role. If you expect to be going downhill an uphill grade can appear downhill to the eyes.

[GrySql]

we can't always believe everything we see since perception plays a big role. If you expect to be going downhill an uphill grade can appear downhill to the eyes.

There is a 20 mile section of I-70E, just past Salina in western Utah, that while the highway elevation rises (GPS & road signs) the river next to it is going downhill. Nevertheless, the water appears to be going uphill.

That is the most disorientating sight, it never fails to amaze me to see such a disparity in an actual vs perception situation. We did this trip again in May and even knowing what I was looking at didn't help the rational of how I could see one thing and the opposite was really occurring.

[Texasota]

Nevertheless, the water appears to be going uphill. That is the most disorientating sight, it never fails to amaze me to see such a disparity in an actual vs perception situation.

I have experienced this same phenomenon in the Colorado rockies. It is very weird.

[OneSpeed]

I have experienced this same phenomenon in the Colorado rockies. It is very weird.

It could be that I did level out and the motor kicked in to maintain speed, but I doubt it. This was a steep constant grade. I did bump up the MPH two or three clicks to test the CC brake but when the speed built up, the cycle started all over again.

 

But I do feel the need to ask again if you are sure the motor does not slow the car when the HVB is fully charged, or if you just think it cant?

[lolder]

The traction motor can only slow down the car when charging load is put on it. If the HVB is full, that doesn't occur. Some or all of these eCVT Ford-Toyota type hybrids may have a mode of braking where continuous application of the brake pedal on a long downhill automatically enables compression braking by the ICE once the HVB is full. I don't know if the ACC in the Gen III 2013+ does this or not.

[OneSpeed]

The traction motor can only slow down the car when charging load is put on it. If the HVB is full, that doesn't occur. Some or all of these eCVT Ford-Toyota type hybrids may have a mode of braking where continuous application of the brake pedal on a long downhill automatically enables compression braking by the ICE once the HVB is full. I don't know if the ACC in the Gen III 2013+ does this or not.

Mine is a 2015 and I was not on the brake. I let the car do what it wanted, and just watched.

 

Today going down hill with cruise on, I tapped the - to lower the CC speed, the car almost instantly compression braked. The engine reved up to 4G to slow the car from 55 to 53.

[Easy Rider]

Mine is a 2015 and I was not on the brake. I let the car do what it wanted, and just watched.

 

Does the '15 still have "descent assist" ?

That sound pretty much like what happens when it kicks in.

[Texasota]

Does the '15 still have "descent assist" ? That sound pretty much like what happens when it kicks in.

 

My 2015 does have the Grade Assist button on the gearshift lever. This is the description of it in the Owner's Manual:

 

 

D (Drive) with Grade Assist (If Equipped)

Press the transmission control switch on the side of the gearshift lever to activate grade assist.

 

Grade assist:

• Provides additional grade braking with a combination of engine motoring and high-voltage battery charging to help maintain vehicle speed when descending a grade.

• As the vehicle determines the amount of engine motoring and high-voltage battery charging, you may notice the engine speed increasing and decreasing to help maintain your vehicle speed when descending a grade.

• The grade assist lamp in the instrument cluster is illuminated. The grade assist lamp will appear in the instrument cluster when grade assist is turned on. Press the transmission control switch again to return to normal D (Drive).

[corncobs]

Mine works as described in the OM.