Ebable sub-freezing regen...

[wwest40]

Ford has a US patent that decribes a technique wherein the regenerative braking is substantially reduced if the OAT declines to freezing and below. The patent also defines a technique wherein should impending wheel lockup be detected by the ABS system during actual braking regen will be INSTANTLY disabled.

Anyone tried defeating the regen reduction via an OAT sensor modification..??

[Formula413]

What he is saying is that the computer will disable regen braking under either cold conditions or wheel lockup. I'm not sure I would want to mess with this if it could mean losing ABS. Is the "OAT" sensor used to determine whether this occurs something different than the IAT sensor? You wouldn't want to mess with the intake air temps, at a minimum this would probably hurt fuel economy, if not the engine itself. If it is using a dedicated sensor that still leaves the ABS issue.

[wwest40]

Most modern day A/C systems include an OAT, Outside Air Temperature, sensor. And I presume that it would be this sensor that is used to determine when to reduce the level of regen used during coastdown periods and when braking is used.

[Formula413]

Originally Posted by wwest40

Most modern day A/C systems include an OAT, Outside Air Temperature, sensor. And I presume that it would be this sensor that is used to determine when to reduce the level of regen used during coastdown periods and when braking is used.

I'm not sure if my Escort has one. I know the manual says that when selecting defrost the compressor engages at temps above 45*F. I could see them being lazy and just using the IAT though.

Any idea why Ford decided to limit regen braking when temps drop?

[wwest40]

"Any idea...??"

Yes, the potential for encountering a patch of ice, BLACK ice, goes up drmatically, and inadvertently having up to ~35HP of regen braking applied to the front wheels upon full throttle lift could too quickly lead to loss of control.

It would be like having the brakes applied without driver input but with no ABS available should the braking cause wheel lockup.

Along the same lines the new VW uses a technique that up-revs the engine should the driver downshift the stick shift to a level that results in front wheel "slip" due to too much engine compression braking.

[Formula413]

Tell me again why you want to disable this???

[wwest40]

"want" is too strong...

In sub-freezing climates regen braking that is primarily from/on the front wheels cannot be used safely to fullest advantage. But disabling the technique would put the driver & passengers at risk.....a higher level of risk.

[gascort]

I've caused lockup before via downshifting (like the VW supposedly prevents now as stated above).
I could see ADVANCED drivers in cold regions disabling it, but would have to be people like us who are anal about controlling every part of our cars to get performance/mpgs.
For the everyday person, the shutoff via the computer of the regen braking is a good safety device.

[MetroMPG]

On the other hand, some cars have buttons that permit drivers to disable stability control/traction control.

But I can't think of one that permits the driver to fiddle with the brakes on the fly.

(Even though there are times when you'd be better of without ABS, for example). As gascort says, ADVANCED drivers only. The average driver wouldn't know when it might be advantageous to use. Applies to overriding regen logic in a hybrid or EV as well.

[wwest40]

Yes, a much more reasonable and functional Anti-lock system would be designed to NOT activate unless VSC indicated the need. No threat to loss of directional control, no needless/detrimental ABS activation.