Brake pedal to the floor?

Ahhhh! So when you touch the door handle, the pump fills the accumulator in preparation for the brakes to be used without the engine being engaged. Very clever! Thanks for the lesson!!

I get a lot of people looking worried and asking my whatthat noise is ("is it going to blow up?) Now I have a non-fiction story to tell them.

 

I come down a very steep hill, (SanFransisco Style) on the way home. I've been practicing not maximizing the regeneration. This leaves me with a little velocity on a very steep down grade with a little momentum at the very end of the stop. I'm not sure what is going on but as the system transitions from regen to normal braking as it must to remove the last few ft/s of velocity something feels like it "fades" I haven't figured out if the breaking fades, or the peddle fades but the end result is the last bit of the stop peddle feels soft and the stop is always a little long. I haven't closed in on the situation because my intial veloicty, regen management and stoping point all have to coincide to get it to happen so I'm not sure what is "sensation" and what is actually happening, but it feels like a bad master cyclender from days gone by although I'm pretty sure it isn't .

 

Cool! I'm going to find a steep hill and see if I can replicate this. The last time we saw it was test driving a 2001 Prius.

When we test drove the 2001 Prius (back in 2001,) I noticed that just under 5 mph there was a detectable transition from regenerative to hydraulic braking. It was subtle yet even my wife noticed it. But I've been driving our 2003 Prius (same NHW11 model) for nearly four years and I don't even notice it.

Thanks,
Bob Wilson

 

Qbee's whole post helps explain the brake feel results I found today while checking out OP's question. My brake is easily pushed down to some hard stop, and it is the same feel whether the car is Off, or On with ICE running. The car was parked during this test, and I've never needed to reach the hard stop while in motion.

I am accustomed to a far harder pedal feel when power assist is absent, from (1) farm equipment with manual brakes; (2) the first two cars I learned to drive, which were subject to stalling and loss of all assist; (3) the next car where the power booster gradually but completely failed; (4) the next car developed a slow vacuum leak in its booster, loosing all stored boost capacity a few minutes after shutdown; (5) the remaining pre-hybrid can be put into no-boost mode by simply pressing the brake multiple times while parked with the engine off.

In all cases, the brakes still worked just fine by simply stomping harder. If one knows what to expect, the resulting stiff pedal force is still manageable because the leg muscles are very strong.

Because the Prius automatically refills the boost accumulator even when the ignition is off, I can't test its non-boost mode by simple applying the brake multiple times until the boost vanishes. Presumably, that hard stop Qbee mentions and I feel is the master cylinder pushrod, ready for action if boost fails. Is it time to test this by pulling a fuse?