Regen braking - when does friction kick in?

The Prius tries to use regen as much as possible. The exact details may vary with your newer Prius, but in general here are the limits:

1) Speed. At low speed MG2 rotates too slowly for effective regeneration, so the Prius transitions to friction. This happens at around 7 mph with the Gen II Prius.

2) Capacity. Regeneration is limited by the ability of MG2 to produce current and the ability of the HV battery to absorb the current. Heavy braking or a high SOC on the battery will limit the amount of regen.

3) Loss of traction. If either of the front drive wheels loses traction, the Prius immediately transitions into ABS friction braking.

4) Panic stop. If you mash the brakes, the Prius assumes that it is a panic situation and goes directly to friction braking with brake assist.

Tom

 

I saw somewhere that there are varying hydraulic pressures to the pads. These pressures would be applied at the point the controller brain thinks they are needed.

I only saw a small handful pressures, though the actual pressure(s) may be much more variable.