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

[Texasota]

Mine works as described in the OM.

Mine too, but the elevated ICE RPMS can sometimes be unsettling and annoying.

[corncobs]

Mine too, but the elevated ICE RPMS can sometimes be unsettling and annoying.

True but safer than riding you brakes and eventually losing them due to overheating. I remember my dad had this problem a long time ago while driving thru the alps pretty scary situation.

[GrySql]

Mine too, but the elevated ICE RPMS can sometimes be unsettling and annoying.

FYI...

The ICE looks after itself and won't over-rev.

 

Engine RPM Limiter

The PCM disables some or all of the fuel injectors whenever an engine RPM or vehicle over speed condition is detected. The purpose of the engine RPM or vehicle speed limiter is to prevent damage to the powertrain. The vehicle exhibits a rough running engine condition, and the PCM stores a diagnostic trouble code (DTC) P0219. Once the engine returns to the normal operating mode. No repair is required. However, the technician should clear the DTCs and inform the customer of the reason for the DTC.

Excessive wheel slippage may be caused by sand, gravel, rain, mud, snow, ice, or excessive and sudden increase in RPM while in NEUTRAL or while driving.

[hybridbear]

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?

As others have stated and as I have stated before: the only way the electric motors can slow the vehicle is by turning kinetic energy into electrical energy and storing it in the HVB. If the electric motors are consuming electrical energy from the HVB there are only 2 possible options:

1. The generator motor is spinning the ICE up to speed to start it
2. The traction motor is converting electric energy to kinetic energy to propel the car

[Easy Rider]

There could be a mode where the traction motor is sending energy to the ICE with the fuel cut off to accomplish "compression" braking without sending anything to the battery, or very little.

 

I don't know for sure that is what is happening but it sure sounds like it.

[OneSpeed]

 

As others have stated and as I have stated before: the only way the electric motors can slow the vehicle is by turning kinetic energy into electrical energy and storing it in the HVB. If the electric motors are consuming electrical energy from the HVB there are only 2 possible options:

• The generator motor is spinning the ICE up to speed to start it
• The traction motor is converting electric energy to kinetic energy to propel the car

I know I sound like I am trying to argue, but I am not.

I am not convinced that you answered my question. Are you certain that the electric motor can't be used to slow the car, or are you just guessing?

If the electric motor can propel the car in forward and reverse, why couldn't it be used to slow the car when the HVB is full and can spare the power? All it is going to do is make heat that can be dissipated.It would be the equivalent of a slight excelleration.

[OneSpeed]

I have the owners manual and I know what it says but it does not say exactly how the system works. It is not a technical shop manual. It is more like a advertisement than a manual.

The system inner workings are very likely to complex for the average owner to care about.

[corncobs]

I know I sound like I am trying to argue, but I am not.

I am not convinced that you answered my question. Are you certain that the electric motor can't be used to slow the car, or are you just guessing?

If the electric motor can propel the car in forward and reverse, why couldn't it be used to slow the car when the HVB is full and can spare the power? All it is going to do is make heat that can be dissipated.It would be the equivalent of a slight excelleration.

Once the HVB is "full" the computer will not allow the traction motor (electric motor) to run as generator because it has no way to get rid of the electricity the generator produces.

 

The brake resistor you would need for this job would be rather big and heavy which takes up space and adds unnecessary weight when instead you can just run the ICE as an air compressor.

 

There is nothing wrong with that since there is no fuel injection and therefore no unwanted use of fuel.

[OneSpeed]

Once the HVB is "full" the computer will not allow the traction motor (electric motor) to run as generator because it has no way to get rid of the electricity the generator produces.

 

The brake resistor you would need for this job would be rather big and heavy which takes up space and adds unnecessary weight when instead you can just run the ICE as an air compressor.

 

There is nothing wrong with that since there is no fuel injection and therefore no unwanted use of fuel.

No brake resistor, reverse. Or a very slight current in reverse, just enough to slow the car.

[lolder]

When the HVB is "Full" and braking is required, electrical power is applied to MG1 ( from MG2, the traction motor ) to cause the eCVT transmission to spin the ICE for compression braking.

[OneSpeed]

When the HVB is "Full" and braking is required, electrical power is applied to MG1 ( from MG2, the traction motor ) to cause the eCVT transmission to spin the ICE for compression braking.

Thank you.

[Easy Rider]

All it is going to do is make heat that can be dissipated.It would be the equivalent of a slight excelleration.

I don't know either but that could be a SUBSTANTIAL amount of heat and dissipating it is not a trivial task.

[OneSpeed]

I don't know either but that could be a SUBSTANTIAL amount of heat and dissipating it is not a trivial task.

As I understand it, the drive motor is inside the transmission. The transmission could have a cooling system the could easily keep up with the HP that this can make.

[GrySql]

Take a look over here, we're reviewing the eCVT.

http://fordfusionhybridforum.com/topic/9602-ffh-factoids-parts-quiz/?p=91409

[lolder]

No braking heat energy is intentionally dissipated in the transmission. It is separately water cooled as both the motor generators have internal electrical losses that produce heat. Braking energy is absorbed first by the HVB, second by compression braking of the ICE and third by the power disc brakes. The disc brakes are also used at any time the desired braking level exceeds the braking available from regenerative braking. I heard an anecdotal item supposedly from a Ford engineer about the Gen I Escapes that if a heavy book on the front of a passengers seat didn't fall forward during a stop, mechanical braking wasn't used. That's a pretty hazy statement. The Gen III HVBs can absorb over twice the power of the Gen I and IIs.

[OneSpeed]

No braking heat energy is intentionally dissipated in the transmission. It is separately water cooled as both the motor generators have internal electrical losses that produce heat. Braking energy is absorbed first by the HVB, second by compression braking of the ICE and third by the power disc brakes. The disc brakes are also used at any time the desired braking level exceeds the braking available from regenerative braking. I heard an anecdotal item supposedly from a Ford engineer about the Gen I Escapes that if a heavy book on the front of a passengers seat didn't fall forward during a stop, mechanical braking wasn't used. That's a pretty hazy statement. The Gen III HVBs can absorb over twice the power of the Gen I and IIs.

I was about to let this thread die, but now I want more answers.

[Easy Rider]

More answers are going to require more specific questions.

[acdii]

In Theory, the MG could be used to brake by consuming energy from the batteries, but I doubt the Fusion has this ability as it would generate a lot of heat. It is also something that 3 Phase motors do, but single phase I don't think can do it, and I don't believe the eCVT is 3 Phase.

 

My RC planes have the ability to brake the motor, they are 3 phase motors running off the same type of batteries the Fusion uses, when in braking mode they stop the prop and hold it against the forces of the wind pushing against the blades so it doesn't freewheel, which also helps to slow the plane. If there is enough forward speed on the plane, the prop can take a bit to slow down, which causes more current draw on the pack and speed controller, and temps go way up. Knowing this, I doubt the eCVT will have this ability, the heat produced would overwhelm the cooling system going down a steep grade.

 

I have to agree though with one of the other posters, you more than likely were on a portion of highway that leveled off. I noticed a lot of times where you think you were going downhill, but were actually climbing, all due to the angles of the rock layers. My recent trip down south through the hills of TN, there were a few times I thought we were going up, but was heading down, and just the opposite too.

 

I don't know if you were looking, but what was your instant MPG showing at the time? Was the ICE on at the same time or just EV only?

[mwr]

Braking energy is absorbed first by the HVB, second by compression braking of the ICE and third by the power disc brakes. The disc brakes are also used at any time the desired braking level exceeds the braking available from regenerative braking.

I've been surprised at how little pressure on the brake pedal causes the friction brakes to engage (as evidenced by a low-ish braking score). Seemingly, anything more than conscious gentle pressure on the pedal, particularly at the beginning of braking, causes the brake score to go below 90, and even below 80 or 70..

[hybridbear]

I've been surprised at how little pressure on the brake pedal causes the friction brakes to engage (as evidenced by a low-ish braking score). Seemingly, anything more than conscious gentle pressure on the pedal, particularly at the beginning of braking, causes the brake score to go below 90, and even below 80 or 70..

This has to do with physics... When your car is moving at a high rate of speed it possesses much more kinetic energy. The maximum charge rate of the HVB is 35 kW. When you're traveling at highway speeds decelerating at a rate of 35 kW is very slow to decrease your speed. In the city you can stop pretty quickly without exceeding 35 kW. The equation for Kinetic Energy (KE) is: KE = 0.5 x mv². Mass is in kilograms and velocity in m/s. The result is KE in Joules. Suppose your car is traveling 60 MPH (26.8 m/s). The FFH weighs about 3800 lbs with car & driver (1723 kg). Thus your KE is 618,763.8 Joules. That equals 171 Wh of energy. It's important to note that 1 Joule equals 1 W/s. That means that to slow the car to a stop at a rate of -1 W/s it would take 618,763.8 seconds to stop the car. Discounting aero drag & friction to stop your car moving at 60 MPH at a constant rate of -35000 W/s would take 17.7 seconds. To slow from 60 MPH to 40 MPH (17.9 m/s) you would be going from 618,763.8 J to 276,033.2 J. Notice that a 33% drop in speed is a 55% drop in KE, this is because velocity is squared in the KE equation. To decrease your KE by 342,730.6 J at a rate of -35000 W/s you'd need to be slowing down for 9.8 seconds. That means you must start braking well in advance to take 10 seconds just to slow down from 60 to 40 MPH (ignoring friction & drag). If you don't brake far enough in advance you won't get a 100% brake score.

 

As your speed drops you're no longer able to slow the car down at a rate of -35000 W/s via regen braking alone. As the RPM of the traction motor drops (its RPM is a linear function based on wheel speed) it can no longer apply so much braking force. Thus your maximum regen braking becomes less than -35000 W/s. At slower speeds this isn't much of a factor though since you have so much less KE than at higher speeds.

Edited January 9, 2015 by hybridbear

[corncobs]

That was "one" great engineering and math post!

 

Thanks HB

[GrySql]

That was "one" great engineering and math post!

 

Thanks HB

This ^^^^ !

 

We need to pin that Post.

Edited January 9, 2015 by GrySql

[lolder]

Look here at the 10 second charge capacity of the C-Max in HVB battery testing ( same drive train ): http://avt.inl.gov/hev.shtml

It's about 48 Kw. That's about 64 hp. The regenerative braking that this would produce is the reverse of what acceleration 64 hp would produce which is about 1/3 of the available which is substantial. Maybe the net effect is only 35 KW. It's difficult to know the braking procedure poster mwr is using to get the lower brake scores.

Edited January 9, 2015 by lolder

[mwr]

Look here at the 10 second charge capacity of the C-Max in HVB battery testing ( same drive train ): http://avt.inl.gov/hev.shtml

It's about 48 Kw. That's about 64 hp. The regenerative braking that this would produce is the reverse of what acceleration 64 hp would produce which is about 1/3 of the available which is substantial. Maybe the net effect is only 35 KW. It's difficult to know the braking procedure poster mwr is using to get the lower brake scores.

My brake scores are fine except when there's an unusual need to brake harder than the normal gentle braking I use. But "harder" really, to me, isn't very hard. Definiitely not hard nough to dislodge anything sitting on the passernger seat; not even close.

[GrySql]

My brake scores are fine except when there's an unusual need to brake harder than the normal gentle braking I use. But "harder" really, to me, isn't very hard. Definiitely not hard nough to dislodge anything sitting on the passernger seat; not even close.

I haven't driven a 2105 FFH and wonder if Ford adjusted something in the Powertrain Control Software (PCS) making the '15 FFH act a bit differently than my 2013.

I can stop pretty hard and still maintain Regen braking, that is why my brake pads were measured today and after 36k miles they have very little wear.

 

Your description makes me think that your car either has a new PCS system or there is something not working correctly. It really couldn't hurt to take the car in to the Dealer and have your brake system looked at - each wheel, rotor and pad. Plus, get the car hooked up to the Ford IDS laptop (Integrated Diagnostic Software) to look for trouble.