In 4A or 4H does regenerative braking operate on all four wheels?

[hpwjr]

I got to wondering how regen braking works. Does it work on all four wheels or just rear wheels and is 4 wheel regenerative braking tied to whether you have the truck in 4A or 4H instead of normal 2wd? I might be taking a trip up north into snow country and thought it might be a disadvantage if regenerative braking only worked on rear wheels. It could produce enough drag to upset the truck’s equilibrium if only the rear wheels slowed down in regeneration braking. What do you experts say?

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[Goldeneye36]

Despite the name, regenerative braking doesn't involve the brakes at all. Very basically: when you let off the gas and coast or lightly press the brake pedal the flow of electricity to the electric motor reverses and acts as a generator that pumps electricity back into the battery. In these trucks, the motor is located between the transmission and the gas engine so the braking force is directed through the transmission into the drivetrain.

Thought experiment and theory crafting to follow:

I'm guessing this thread comes up due to some information posted recently in another thread about PowerBoost trucks being sketchy in the snow in certain situations. Sitting here and pondering it, how that Regen is transferred should, in theory, depend on what 4wd mode you are in and what transfer case you have. Since the rear wheels are always driven, they will always see the effects of Regen braking. Seeing as how the transfer case is mounted on the output side of the transmission, any Regen braking should be transferred to the front wheels as well if the transfer case is engaged. Does this differ between the ESOF (mechanical locking) vs TOD (clutches) transfer cases? Maybe, maybe not, I can't say for sure. I would need to go back and re-read the threads mentioned to see what trim levels the OPs have. I've yet to drive my XLT PB in the snow so I can't offer any anecdotal experience, just guesses based on what I know about these trucks mechanically.

 

[DT444T]

Braking. It's spelled braking.

>Does it work on all four wheels or just rear wheels
Regen braking can only work on driven wheels. If you're in 2wd it can only brake through the rear wheels.

>Is 4 wheel regenerative braking tied to whether you have the truck in 4A or 4H instead of normal 2wd?
Yes. But it does it less in 4A/4H (any non-2wd)

If you look at the Eco Coach screen it shows the little gauge that says Hybrid or Electric while driving it will show a larger available regenerative braking available when in 2wd. When in anything that's not 2wd it will limit the amount of regen. This seems counter-intuitive to me, but what do I know.

 

[FaaWrenchBndr]

Regenerative braking is done through the electric motor in the transmission. It has zero to do with the actual wheel mounted brakes.

 

[hpwjr]

Please don’t tell my mother I spelled braking breaking. But I see the key question now since the generator is tied to the transmission before the transfer case. I understand it does not use the disc brakes (not breaks), but it does “brake” as it converts kinetic energy of forward motion into electrical energy to store in the battery. So I suppose it all depends in 4A whether the electronics are sending torque to the front wheels. In 4H I would expect it to be constant both front and rear. Is this correct? Is there a way to go back and edit my title and original post so my mother will never see it?

 

[DT444T]

In 4H I would expect it to be constant both front and rear. Is this correct?

Yes, because the torque split is 50/50 with a transfer case.

 

[Aonarch]

Regen braking on a EV/ PHEV is always through the electric motor and NOT through the hydraulic brakes.

 

[Nassau]

I got to wondering how regen braking works. Does it work on all four wheels or just rear wheels and is 4 wheel regenerative braking tied to whether you have the truck in 4A or 4H instead of normal 2wd? I might be taking a trip up north into snow country and thought it might be a disadvantage if regenerative braking only worked on rear wheels. It could produce enough drag to upset the truck’s equilibrium if only the rear wheels slowed down in regeneration braking. What do you experts say?

The technical answers you got in this thread earlier, but it took a while to get there. The answer to your important question about driving on icy roads is this. I have had my PB f150 for a year now. And have driven on really icy roads and on slick snow covered roads. I never once noticed any issues or concerns with how the regen works and interacts with the true brakes. Not once. So don’t sweat it at all.

 

[hpwjr]

I’m going back to sleep. It did make a lot of sense that the regen brake force could alter driving dynamics while coasting. But I’ll believe real world experience.

 

[Goldeneye36]

The technical answers you got in this thread earlier, but it took a while to get there. The answer to your important question about driving on icy roads is this. I have had my PB f150 for a year now. And have driven on really icy roads and on slick snow covered roads. I never once noticed any issues or concerns with how the regen works and interacts with the true brakes. Not once. So don’t sweat it at all.

For data: what trim level is your truck?

 

[hpwjr]

Lariat high

 

[SonarChief]

Lariat high

If your trim has the drive mode “slippery”, then using this mode means regen braking isn’t used.

 

[Nassau]

For data: what trim level is your truck?

Lariat 502A

 

[JumboJVT]

My related question about 4A in bad conditions applies to non-PB's as well: does 4A transfer compression braking to the front axle? Obviouly locked in 4H it does.

I've seen just in the last two weeks (snow every day, roads not-so-hot) running in 2W, brake a bit and get a downshift from the transmission (it will shift down under braking, too bad it won't under light accelleration) that adds to the rear axle's braking effect causing a loose rear end. The antilock can release the friction brakes but can't do anything about the compression braking being applied to the hind end. Things can get squirrly fast. Simple answer on my non-4A 302A is 4H. But does 4A activate regardless of which wheels are moving slower. i.e. does it activate when the rear wheels are turning slower than the fronts, as well as when turning faster than the fronts? If it doesn't, could this be exactly why the regen braking on a PB is disabled in "slippery" mode? Even simple compression braking applied to all 4 wheels isn't always desirable when things are sketchy.

 

[TheGoatman]

You need to combine the eco coach in 4wd and eco coach and power distribution to see in 4a.

If eco coach shows regen and power distribution is up for the front wheels, then the fronts are doing what you’re asking

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