Powerboost Winter driving and handling characteristics

Norheat

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Has anyone noticed that their Powerboost hybrid wants to lock up the rear tires and pull the arse end around under breaking, on winter snow and ice covered road conditions?

It only seems to happen under light breaking when the battery is charging.





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chrisp993

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Normally, braking system is designed (since under braking the weight/grip transfers to the front) so that more braking force (bias) would be applied to the fronts than rears.

Most people are familiar with the "engine braking" aspect of decelerating in gear - in a 2WD, this braking force would be through the driven i.e. rear wheels ... and if regenerative braking is in play, in 2WD, this force would also be through the rear wheels.

It would make sense to design the F150s braking system for normal operation - not regenerative braking - meaning that when the regenerative braking is in play, the rear wheels see significantly more braking force than they normally would = tendency to slide out?

Does the same thing happen in 4H, when the regenerative force would be spread between front and rear tires?
 
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Norheat

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Normally, braking system is designed (since under braking the weight/grip transfers to the front) so that more braking force (bias) would be applied to the fronts than rears.

Most people are familiar with the "engine braking" aspect of decelerating in gear - in a 2WD, this braking force would be through the driven i.e. rear wheels ... and if regenerative braking is in play, in 2WD, this force would also be through the rear wheels.

It would make sense to design the F150s braking system for normal operation - not regenerative braking - meaning that when the regenerative braking is in play, the rear wheels see significantly more braking force than they normally would = tendency to slide out?

Does the same thing happen in 4H, when the regenerative force would be spread between front and rear tires?
Yes, it does not appear to make much difference whether in 2wd or 4H.

I was also in the slippery setting. Braking works fine if you actually brake.

It would have been nice to have a brake bias control so I could put more to the front like my racecar 🤔🤣. The problem seems to be only under light breaking. The regenerate braking and charging of the battery, does not appear to be that good in the snow and ice. Going to take a few trips to get used to it.

You definitely can feel the right rear grab first and want to pull you around. Especially when slowing down for a corner.

This was on full snow and ice covered roads. The system is fine in wet or dry pavement. Very light brake pressure is when it grabs. Makes it different to drive on ice and snow.
 
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don.mullins

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Yes, it does not appear to make much difference whether in 2wd or 4H.

I was also in the slippery setting. Braking works fine if you actually brake.
I thought Slippery Mode went to 4A.
 
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Norheat

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I thought Slippery Mode went to 4A.
yes it does. I drove in Normal, slippery and 4H with the same results in each. Traction was not the issue while accelerating, it was the braking and when I say light, I mean gentle , like gliding to a stop or slowing around a corner. The rear brakes are grabbing and want to lock up. I did have a Hill assist fault on my Ford Pass App that they could not find on the trucks computer. I wonder if Hill assist is all part of the traction control etc. I think that I will mention it to the dealer and see what they say.
 
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Roger350

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yes it does. I drove in Normal, slippery and 4H with the same results in each. Traction was not the issue while accelerating, it was the braking and when I say light, I mean gentle , like gliding to a stop or slowing around a corner. The rear brakes are grabbing and want to lock up. I did have a Hill assist fault on my Ford Pass App that they could not find on the trucks computer. I wonder if Hill assist is all part of the traction control etc. I think that I will mention it to the dealer and see what they say.
This is very concerning. I was hoping the weight of the battery was going to help winter driving responses, but would not have guessed the regen-braking was going to make the vehicle harder to control. It would be great for the rest of us if you have a wheel speed sensor fault or something that is causing this, but I'm not going to hold my breath on that possibility. They may have missed something when programming all the computers that do the hand off from regen to hydraulic braking.
 
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This is very concerning. I was hoping the weight of the battery was going to help winter driving responses, but would not have guessed the regen-braking was going to make the vehicle harder to control. It would be great for the rest of us if you have a wheel speed sensor fault or something that is causing this, but I'm not going to hold my breath on that possibility. They may have missed something when programming all the computers that do the hand off from regen to hydraulic braking.
I am going to have the dealer investigate. I almost backed it into the corner today coming off the Hwy onto the off ramp. Hardly touched the brakes and it again wanted to pull the ass around.

It is significantly worse in Normal mode in 2wd. I went and did some testing in all of the drive modes.

It appears to be working as close to normal in A4 in Normal mode. Slippery mode helps a lot for acceleration, as you can actually feel (what feels like all 4 brakes)holding back the truck on acceleration,

4H also seems the rear brakes are grabbing as well, but not nearly as much as 2wd.

Honestly, if you were driving in 2wd and didn't switch to 4A and tried to brake on Snow or ice, you better hang on.

I really hope that it's just a problem, if not wow it's going to be a problem that needs addressed.
I will keep you posted.
 
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TheGoodLife

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I am going to have the dealer investigate. I almost backed it into the corner today coming off the Hwy onto the off ramp. Hardly touched the brakes and it again wanted to pull the ass around.

It is significantly worse in Normal mode in 2wd. I went and did some testing in all of the drive modes.

It appears to be working as close to normal in A4 in Normal mode. Slippery mode helps a lot for acceleration, as you can actually feel (what feels like all 4 brakes)holding back the truck on acceleration,

4H also seems the rear brakes are grabbing as well, but not nearly as much as 2wd.

Honestly, if you were driving in 2wd and didn't switch to 4A and tried to brake on Snow or ice, you better hang on.

I really hope that it's just a problem, if not wow it's going to be a problem that needs addressed.
I will keep you posted.
Please do keep us in the loop here. I do a lot of driving in the snow, and am coming down a twisty/windy mountain pass at least 1x/week. We are often crawling down the mountain with slow, snowy hairpin turns every 2-300 yards where we are constantly downshifting and doing the slow gentle braking you described. This is one reason I’m really looking forward to my truck. I’m super excited about my powerboost, but if it handles worse in the snow and ice when braking, that would honestly be super dangerous in my situation. I’m tremendously excited for the powerboost and will take the hit to payload and quirks that come with new technology, but if the handling is worse under the most dangerous conditions, I’d rather have the standard V6 ecoboost.

Please keep us updated. My truck was supposedly built this past Wednesday...

Thank you!
-Ryan
 
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Please do keep us in the loop here. I do a lot of driving in the snow, and am coming down a twisty/windy mountain pass at least 1x/week. We are often crawling down the mountain with slow, snowy hairpin turns every 2-300 yards where we are constantly downshifting and doing the slow gentle braking you described. This is one reason I’m really looking forward to my truck. I’m super excited about my powerboost, but if it handles worse in the snow and ice when braking, that would honestly be super dangerous in my situation. I’m tremendously excited for the powerboost and will take the hit to payload and quirks that come with new technology, but if the handling is worse under the most dangerous conditions, I’d rather have the standard V6 ecoboost.

Please keep us updated. My truck was supposedly built this past Wednesday...

Thank you!
-Ryan
Ryan, you are going to love this truck. It's just awesome. I will take it to the dealer this week and let you know when I find out anything.
If you put it in A4 Normal, or slippery it appears to work fine. 2wd is dangerous! I am very surprised that there is no anti lock on the rear regen mode in 2wd. Trust me, you will only forget to put it in A4 or Slippery once 😂.
It also does not take alot of snow to make this issue happen.
I will keep you posted.
 

don.mullins

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Has anyone noticed that their Powerboost hybrid wants to lock up the rear tires and pull the arse end around under breaking, on winter snow and ice covered road conditions?

It only seems to happen under light breaking when the battery is charging.
OK, I just had to run some errands, so I have an initial impression. I tried Deep Snow/Mud (4H, no locker) and Normal (4H).

I saw higher engine revs in Deep Snow. Since I was seeing a mix of clear and patchy snow/ice on the roads, I didn’t keep the rear locked, which is the default for this mode. I saw more electric only in Normal (4H). Acceleration was smooth in both modes. Braking felt controlled in both. Maybe I was too patchy with too much clear road to get a good comparison.

I did hear/feel some knocking in Deep Snow mode while turning before I disengaged the rear locker. I was on 6” or so of snow and crawling along to get out of my alley when I felt that. I disengaged since I knew the roads were clearing. I am new to 4x4 and not sure when I should or shouldn’t lock the rear, but I do understand why there is a differential (that locking disables).
 
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Yes, deep sand and snow is definitely got what I would call a power surge, if you compare it to slippery mode in 4A.

The locking rear end will also only engage below a certain speed. I have never used it.

I was out most of the day driving in snow covered roads in slippery mode with it in 4A. It worked fine.

I have appointment with the dealer Thursday. They want to look at it and are speaking with Ford to get an idea of what the answer maybe.

I said, I bet they say the answer is don't drive in 2wd normal mode in snow conditions LOL..

But they are going to look at it anyway.
 

Jus Cruisin

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I'll be picking up my Powerboost Thursday. Sounds like this hybrid will have a learning curve....
 
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The dealer is looking at my truck for the next day or so. I have spoken with the Ford dealer shop manager and they are going to get to the bottom of this.
I should know more tomorrow afternoon.

I think I know what the problem is after speaking with the shop manager. I learned alot about how a hybrid works.
What I am calling regen braking is actually a motor and really has nothing to do with the brakes, other than it uses the rear wheels to spins the motor. At least that is the way I see it in my head. Don't quote me on it. Lol.

I think it is the drag on the regen motor that causes the rear wheels to slip or lock on ice and snow covered roads.
Only in 2wd normal mode and only under very lightly touching the brakes.

They are going to get back to me and I will let you.
 
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Roger350

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Yes, that is my understanding of how regen braking works also. It is really old fashioned "engine" braking letting the drivetrain drag slow you down. The electronic controls and special electronic master cylinder are just allowing this parasitic drag from the drivetrain to occur with light application of the brake pedal with no engagement of the hydraulic friction brakes, and then at some point the computer decides it needs the hydraulic friction brakes involved and it hands it over to them. The "engine" braking turns the electric motor into an electric generator, charging the battery.

It's been a long time since I've driven in bad winter conditions so I could be completely wrong on the rest of this, but I'm assuming that the drivetrain drag in the PowerBoost is a little too significant, kind of like engine braking in too low a gear, so it is not the gentle let your foot off the brakes and coast type dynamic response. Instead the heavy drivetrain drag is causing you to lose the tail because it is trying to decelerate too much too soon.

I would assume that in 4wd the fronts being engaged is splitting the braking torque more equally among all 4 wheels so none are locking up.

Not sure there is going to be a way to fix this. The fix would likely be some complex reprogramming of the software that controls the hand-off between the regen function and the hydraulic friction brakes.

Honestly this hand-off is the number one complaint of every journalist and driver (including myself with my Hyundai Sonata Hybrid). Weird brake feel due to trying to juggle regen and hydraulics. I think they should just leave it like the old days, when you apply even slight pressure to the brake pedal you ought to be getting hydraulic breaking, and if you just coast with no foot on either pedal you get regen. I can't remember who it is, if it's the GM Volt/Bolt or Tesla or someone else, but they added a paddle or thumb button to the steering wheel that you can use when you want regen braking to be more active. That would be a better solution in my mind than this computer hand-off BS.

Long rant over, sorry TLDR I know.

I think we're all just going to have to use Slippery mode when conditions are slick. Will be interested in seeing how it responds on rain covered roads, if it is as noticeable, or if it really needs to be slick snow/ice to set up this undesirable behavior.

Thanks for keeping us posted!
 
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Norheat

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Yes, that is my understanding of how regen braking works also. It is really old fashioned "engine" braking letting the drivetrain drag slow you down. The electronic controls and special electronic master cylinder are just allowing this parasitic drag from the drivetrain to occur with light application of the brake pedal with no engagement of the hydraulic friction brakes, and then at some point the computer decides it needs the hydraulic friction brakes involved and it hands it over to them. The "engine" braking turns the electric motor into an electric generator, charging the battery.

It's been a long time since I've driven in bad winter conditions so I could be completely wrong on the rest of this, but I'm assuming that the drivetrain drag in the PowerBoost is a little too significant, kind of like engine braking in too low a gear, so it is not the gentle let your foot off the brakes and coast type dynamic response. Instead the heavy drivetrain drag is causing you to lose the tail because it is trying to decelerate too much too soon.

I would assume that in 4wd the fronts being engaged is splitting the braking torque more equally among all 4 wheels so none are locking up.

Not sure there is going to be a way to fix this. The fix would likely be some complex reprogramming of the software that controls the hand-off between the regen function and the hydraulic friction brakes.

Honestly this hand-off is the number one complaint of every journalist and driver (including myself with my Hyundai Sonata Hybrid). Weird brake feel due to trying to juggle regen and hydraulics. I think they should just leave it like the old days, when you apply even slight pressure to the brake pedal you ought to be getting hydraulic breaking, and if you just coast with no foot on either pedal you get regen. I can't remember who it is, if it's the GM Volt/Bolt or Tesla or someone else, but they added a paddle or thumb button to the steering wheel that you can use when you want regen braking to be more active. That would be a better solution in my mind then this computer hand-off BS.

Long rant over, sorry TLDR I know.

I think we're all just going to have to use Slippery mode when conditions are slick. Will be interested in seeing how it responds in rain covered roads, if it is as noticeable, or if it really needs to be slick snow/ice to set up this undesirable behavior.

Thanks for keeping us posted!
Thanks Roger350.

Yes, I think that is what is going on. On dry, wet roads there is no problem because there is enough friction to maintain control of the contact with the road.
On Snow and ice the wheels slide instead of rolling, is the way I see it.

If this is the case, I am not sure how you would fix it, other than drive in slippery. It's the first report so they are involving the ford engineering department to try and figure this out.

Fingers crossed it is nothing but a required update.

I will know Friday afternoon.
 

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