Jump to content

Custom Search




Welcome to the C-MAX Hybrid Forum


Sign In  Log in with Facebook

Create Account
Welcome to the C-MAX Hybrid Forum. You must register to create topics or post in our community, but don't worry this is a simple free process that requires minimal information for you to signup. Here's some member benefits:
  • Start new topics and reply to others
  • Subscribe to topics and forums to get email updates
  • Get your own profile page and make new friends
  • Send personal messages to other members
  • Create photo albums and post images. . .more!
Click here to create an account now
 
Guest Message by DevFuse

Get you C-MAX Hybrid Registered in the official Ford Authorized Registry. More here.


Photo

Mountain Driving Help


  • Please log in to reply
54 replies to this topic

#1 OFFLINE   fotomoto

fotomoto

    C-Max Hybrid Member

  • C-MAX Hybrid Member
  • 1,297 posts
  • Region:Decline
  • LocationSouth Texas
  • My C-MAX's Color:Ruby Red
  • Current Vehicle:C-Max SEL

Posted 06 August 2013 - 11:26 AM

I live along the coast and have no experience yet with mountain driving in my 4 month old CMax.  We will soon be taking a trip to the mountains up to 9,000 ft. and will, of course, experience significant downhill grades.

 

Manual says:

 

 

In prolonged mountainous driving, you may see the engine tachometer changing without your input. This is intentional and maintains the battery charge level. You may also notice during extended downhill driving that your engine continues to run instead of shutting off.

During this engine braking, the engine stays on, but it’s not using any fuel. You may also hear a slight whine or whistle when operating your vehicle. This is the normal operation of the electric generator in the hybrid system. 

 

Should I keep grade assist on all the time?  When or will I ever need to use L gear if using grade assist?  

 

I want to #1) not overheat friction brakes (safety) and #2) strive for best mpg.

 

 


Edited by fotomoto, 06 August 2013 - 11:28 AM.








Lose this advertisement by becoming a member. Click here to create a free account.


#2 OFFLINE   mtb9153

mtb9153

    Brother Mike (a.k.a. mtb9153)

  • C-MAX Hybrid Platinum Member
  • 1,523 posts
  • Region:U.S. Pacific Coast
  • LocationS.F. South Bay Area, Ca.
  • My C-MAX's Year:2013
  • My C-MAX's Color:White Platinum
  • Current Vehicle:2013 C-Max SEL with 303A, with Panoramic window using GasPods on the roof, born 9/9/12

Posted 06 August 2013 - 12:39 PM

I have found that I can maintain good fuel usage and economy by staying in the slow lane and watching the left screen where the Average MPG is displayed.  As I climb a hill I apply pressure on the gas pedal but keep the white line on the left side of the screen so that it never exceeds the 2-bar line.  This seems to give me better fuel economy.


Edited by mtb9153, 06 August 2013 - 12:40 PM.


#3 OFFLINE   DR61

DR61

    C-Max Hybrid Member

  • C-MAX Hybrid Member
  • 53 posts
  • Region:U.S. Pacific Coast
  • LocationRedding, CA
  • My C-MAX's Color:Ingot Silver
  • Current Vehicle:C-Max Energi, Mini ALL4

Posted 06 August 2013 - 12:57 PM

Should I keep grade assist on all the time?  When or will I ever need to use L gear if using grade assist?  

 

I want to #1) not overheat friction brakes (safety) and #2) strive for best mpg.

 

 

I think actively managing your car is best in mountain driving.  I use D on upgrades, so if I let off the pedal some momentum is retained.  I use L on very twisty sections so I can get high regen when backing off to slow for corners, hopefully without having to engage friction brakes.  I use L or grade assist on downgrades, depending on how curvy it is.  On some downgrades that are straight and lead to long flat sections or upgrades, I shift to D or N (if speed is safe) to maximize momentum for the upgrade.



#4 OFFLINE   BIG ROCCO

BIG ROCCO

    C-Max Hybrid Member

  • C-MAX Hybrid Member
  • 235 posts
  • Region:U.S. Mountain
  • LocationPHOENIX, AZ
  • My C-MAX's Color:White Platinum
  • Current Vehicle:2013 C-MAX

Posted 06 August 2013 - 05:34 PM

How does L differ from Grade Assist?



#5 OFFLINE   Ryan McEachern

Ryan McEachern

    C-Max Hybrid Member

  • C-MAX Hybrid Member
  • 108 posts
  • Region:Canada British Columbia
  • LocationMaple Ridge
  • Current Vehicle:Chrysler Town and Country Van (C-Max ordered)

Posted 06 August 2013 - 09:11 PM

Grade assist will use regen to try to maintain your speed when being pulled downhill by gravity. If you engage it at 50 miles per hour, it will apply progressively more are more regen as you speed up past 50 rolling downhill. It will not apply the friction brakes though. In one sense it is like a reverse cruise control for downhills. I like it very much.

Using low gear, is just forcing the regen to maximum as soon as you let off the gas pedal. It is useful for slowing down the car as fast as possible without using the friction brakes, however, once you drive the car for a while, you will get a feel for how much you can push the brake pedal to get max regen, without using any friction brakes. The problem with using low is that coasting is always more effecient that regenerating power and then burning it again, so for downhill driving, it is better to use "D" and engage hill assist to hold your speed down, because then it will let you coast more once the speed drops below the hill assist threshold. (yes, I know there is still a little regen all the time in "D", but it is much closer to coasting than "L")

#6 OFFLINE   zhackwyatt

zhackwyatt

    C-Max Hybrid Member

  • C-MAX Hybrid Member
  • 829 posts
  • Region:U.S. Mountain
  • LocationPhoenix, AZ
  • My C-MAX's Year:2013
  • My C-MAX's Color:Ruby Red
  • Current Vehicle:'13 C-Max Sel 303A

Posted 06 August 2013 - 09:35 PM

I believe L also does Engine braking.



#7 OFFLINE   wab

wab

    C-Max Hybrid Member

  • C-MAX Hybrid Member
  • 927 posts
  • Region:U.S. Southern Plains
  • Locationnorth texas
  • My C-MAX's Year:2013
  • My C-MAX's Color:White Platinum
  • Current Vehicle:C-Max SEL 303 with Glass Roof

Posted 06 August 2013 - 10:08 PM

Are you planning to hypermile up and down or just drive up and down safely?

 

 

I don't hypermile but have found that I can touch the brake just enough to regin and not use the friction pads.

 

You're battery will be at 100% quickly.

 

 

I use the hill descent but turn it off when our speed starts to drop.

When our speed builds I briefly use the friction pads.

Haven't used L.

 

 

Short version:

 

I drive it like a normal car but the people behind are probably thinking

:lol2:

 

" there goes another flat lander burning up his brakes."

 



#8 OFFLINE   bigalpha

bigalpha

    C-Max Hybrid Member

  • C-MAX Hybrid Member
  • 356 posts
  • Region:Decline
  • LocationTucson, AZ
  • My C-MAX's Color:White Platinum
  • Current Vehicle:CMAX

Posted 06 August 2013 - 10:08 PM

I made the mistake of using only brake while going down a mountain grade and I stopped for a break and I could smell the brakes - they were HOT.  At the same time, I don't like using the downhill descent control.  I feel like it uses way too much regen/transmission braking.  It was almost maxed out.



#9 OFFLINE   Plus 3 Golfer

Plus 3 Golfer

    C-Max Hybrid Member

  • C-MAX Hybrid Member
  • 1,657 posts
  • Region:Decline
  • LocationTN
  • My C-MAX's Year:2013
  • My C-MAX's Color:Oxford White
  • Current Vehicle:2013

Posted 07 August 2013 - 09:39 AM

With my C-Max once the battery level is virtually full, I "downshift" / "upshift" between "L" / "D" to help control speed going down long, steep grades and thus limit the use of the friction brakes and potentially overheating the brakes.


  • ptjones likes this

#10 OFFLINE   wab

wab

    C-Max Hybrid Member

  • C-MAX Hybrid Member
  • 927 posts
  • Region:U.S. Southern Plains
  • Locationnorth texas
  • My C-MAX's Year:2013
  • My C-MAX's Color:White Platinum
  • Current Vehicle:C-Max SEL 303 with Glass Roof

Posted 07 August 2013 - 09:45 AM

Plus 3

 

The car will continue to regin after the bat is at 100%, what does it do with the juice? Heat Sink?



#11 OFFLINE   Plus 3 Golfer

Plus 3 Golfer

    C-Max Hybrid Member

  • C-MAX Hybrid Member
  • 1,657 posts
  • Region:Decline
  • LocationTN
  • My C-MAX's Year:2013
  • My C-MAX's Color:Oxford White
  • Current Vehicle:2013

Posted 07 August 2013 - 10:57 AM

Plus 3

 

The car will continue to regin after the bat is at 100%, what does it do with the juice? Heat Sink?

 

That's a good question.  Because once the battery is full how does the algorithm simulate "engine braking" of a conventional car when coasting.  

 

My guess is the engine begins to spin once the battery is full. I doubt there's a heat sink (although I suppose the algorithm could use the friction brakes). I really never monitored engine rpm going down a long steep hill. In a few weeks I should be able to test this out. I also don't know whether my battery was completely charged in prior uses of "L" as the hills were not that long just steep.

 

When you shift the hybrid to "L", the generator MG1 must supply holding torque to the sun gear so that ICE begins to spin if ICE were stopped or spins faster if ICE were already spinning.   The increase in rpm of the spinning engine (no additional fuel supplied) acts as additional load on the final drive to slow the car down. So there is energy being used by MG1 to increase ICE rpm, slow down MG1 and slow down the car when one shifts to "L".  The traction motor could also be used to help simulate this shifting into a lower gear by generating energy that then is directly used by MG1 to keep ICE spinning.  So the net affect might be near zero change in electrical energy but for MG1 and MG2 losses.

 

The more I think about it, I believe ICE has to start spinning when the battery is near 100% full.



#12 OFFLINE   slampro

slampro

    C-Max Hybrid Member

  • C-MAX Hybrid Member
  • 211 posts
  • Region:U.S. Mountain
  • LocationEL Paso
  • My C-MAX's Year:Decline
  • My C-MAX's Color:Tuxedo Black
  • Current Vehicle:2008 Escape Hybrid, Cmax Hybrid Sel 303A, pano roof.

Posted 07 August 2013 - 06:41 PM

The more I read from +3, the more I am :confused:  :headscratch:  By the time I get done I feel like :twister:  hit me.

 

I love how technical you get, even if it mostly goes over my head. It has led to much learning, for many others as well, I am sure.

 

:worship:  :worship: 


Edited by slampro, 07 August 2013 - 06:43 PM.


#13 OFFLINE   ScubaDadMiami

ScubaDadMiami

    C-Max Hybrid Member

  • C-MAX Hybrid Platinum Member
  • 1,408 posts
  • Region:U.S. Southern Atlantic
  • LocationMiami Beach, Florida
  • My C-MAX's Year:2013
  • My C-MAX's Color:Oxford White
  • Current Vehicle:SEL, 303A, Panoramic Roof

Posted 08 August 2013 - 11:30 PM

Is there a max suggested safe speed for shifting to L?



#14 OFFLINE   Plus 3 Golfer

Plus 3 Golfer

    C-Max Hybrid Member

  • C-MAX Hybrid Member
  • 1,657 posts
  • Region:Decline
  • LocationTN
  • My C-MAX's Year:2013
  • My C-MAX's Color:Oxford White
  • Current Vehicle:2013

Posted 09 August 2013 - 12:17 AM

Is there a max suggested safe speed for shifting to L?

I don't believe there needs to be since the PCM controls MG1, MG2, and ICE. It's not like "L"is a fixed gear ratio like in a conventional transmission.
  • SOMD likes this

#15 OFFLINE   MtnMarty

MtnMarty

    C-Max Hybrid Member

  • C-MAX Hybrid Member
  • 177 posts
  • Region:U.S. Southern Atlantic
  • LocationAsheville, NC
  • My C-MAX's Color:Ruby Red
  • Current Vehicle:Ford C Max Hybrid

Posted 09 August 2013 - 06:49 AM

I wish I could use downhill assist but it doesn't work on my car. Dealer put in a query to Ford for me and they're supposed to fix it next week when I go in for the headliner. When I push the button on the side of the shifter, nothing happens.

#16 OFFLINE   fotomoto

fotomoto

    C-Max Hybrid Member

  • C-MAX Hybrid Member
  • 1,297 posts
  • Region:Decline
  • LocationSouth Texas
  • My C-MAX's Color:Ruby Red
  • Current Vehicle:C-Max SEL

Posted 09 August 2013 - 08:45 AM

Is there a max suggested safe speed for shifting to L?

 

From page 209 of the OM:

 

 

L (Low)
Provides maximum engine braking.
The transmission may be shifted into L (Low) at any vehicle speed. 


  • ptjones and ScubaDadMiami like this

#17 OFFLINE   viajero

viajero

    C-Max Hybrid Member

  • C-MAX Hybrid Member
  • 81 posts
  • Region:U.S. Southern Plains
  • LocationAustin TX
  • My C-MAX's Color:Ingot Silver
  • Current Vehicle:C-Max Energi

Posted 09 August 2013 - 05:27 PM

Someone on this forum reported that the ICE spins for engine braking on a downgrade once the battery is full, but I don't remember where it was.

 

I don't think the friction brakes will ever grab in any mode unless you press the brake pedal.  But, you can press the brake pedal to some unknown threshold and only get regen (no friction brakes).



#18 OFFLINE   stratosurfer

stratosurfer

    New Member

  • C-MAX Hybrid Member
  • 11 posts
  • Region:U.S. Southern Plains
  • LocationCentral Texas
  • My C-MAX's Color:White Platinum
  • Current Vehicle:CMax SEL Hybrid

Posted 10 August 2013 - 06:28 AM

Are you planning to hypermile up and down or just drive up and down safely?

 

 

I don't hypermile but have found that I can touch the brake just enough to regin and not use the friction pads.

 

You're battery will be at 100% quickly.

 

 

I use the hill descent but turn it off when our speed starts to drop.

When our speed builds I briefly use the friction pads.

Haven't used L.

 

 

Short version:

 

I drive it like a normal car but the people behind are probably thinking

:lol2:

 

" there goes another flat lander burning up his brakes."

Question: 

Is the brake light on when in regen braking??

I guess so huh?

Folks probably think I'm always riding my brakes.

 

Mark



#19 OFFLINE   wab

wab

    C-Max Hybrid Member

  • C-MAX Hybrid Member
  • 927 posts
  • Region:U.S. Southern Plains
  • Locationnorth texas
  • My C-MAX's Year:2013
  • My C-MAX's Color:White Platinum
  • Current Vehicle:C-Max SEL 303 with Glass Roof

Posted 10 August 2013 - 06:43 AM

Question: 

Is the brake light on when in regen braking??

I guess so huh?

Folks probably think I'm always riding my brakes.

 

Mark

 

Brake light switches are usually adjustable.

 

 

I'll crawl under there and see.

 

Would be good to regin and NOT have the light on.



#20 OFFLINE   fotomoto

fotomoto

    C-Max Hybrid Member

  • C-MAX Hybrid Member
  • 1,297 posts
  • Region:Decline
  • LocationSouth Texas
  • My C-MAX's Color:Ruby Red
  • Current Vehicle:C-Max SEL

Posted 10 August 2013 - 07:58 AM

Brake light is NOT on during regen nor is it required to be. 








Custom Search




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users

Privacy Policy TERMS OF SERVICE ·