Toyota Prius braking problems

[doug]

Interesting:
from NHTSA.gov Don't know how to link to the exact report, but it's pretty easy to search for. Of note, this was just submitted today for a July 15th, 2009 incident.

ummm, yes.
It's discussed here and mentioned at the beginning of this thread. Just submitted today?

 

[efusco]

ummm, sorry. Perhaps I looked at the page wrong, but it had today's date and that appeared to be the submission date...but obviously it's been up since at least October.

 

[DrTaras]

Officially, Official: Toyota recalls 2010 Prius and HS250h for ABS fix — Autoblog Green
"Some 2010 model year Prius and 2010 HS 250h owners have reported experiencing inconsistent brake feel during slow and steady application of brakes on rough or slick road surfaces when the ABS is activated in an effort to maintain tire traction. "

I don't have sophisiticated knowledge of the Roadster's (or any car's) braking system, but when I read that I thought to myself that both my Roadsters have had that exact same problem. When I am braking and my car goes over a pot hole, mini-speedbump or crack in the road, for a few miliseconds the brakes let go, lunge forward and then regrip. Scared me the first few times I was exiting the freeway on my commute to work, but thought it was worth mentioning especially as I found it on both my 2008 & 2010 Roadsters!

 

[ChargeIt!]

In a "regular" (ICE) car ... when ABS activates, it is usually accompanied by a "stuttering" of the brake pedal while you press it hard and/or hit something slippery, but not much (at least from what the driver "feels" (note all the subjectivity here)) in the way of overall "loss of braking", at least not in the types of situations Dr. Taras describes.

In the reported issues on Toyotas (and other hybrids in general) the situation is probably exacerbated because the "computer" has so many more "things" to deal with, most notably regen.

The Tesla does not have the type of regen-activated-by-brake-pedal as does everybody else. But it too has to deal with the strong regen during deceleration (activated by the "go" pedal no longer being depressed while you step on the brake) at the same time as ABS and Traction Control monitoring. I am wondering if the "computer" is being overwhelmed, more so in the case of Tesla (due to extra complexity) than in Toyotas ?

It seems to me -- but I could be wrong -- that the Tesla has all that T/C+Regen+ABS centralized on a single CPU ... which leads to a number of other interesting questions (fault-tolerance, anyone ?). In addition, the Tesla seems to be much more "sensitive" about minor events (again, like those described by Dr. Taras and others, including Toyota owners). Is this the price that must be paid in a car with regen?

 

[raymond]

So, I don't really consider the Tesla system better...it may be smoother and avoid the transition, but it limits driver control of regen and probably reduces the overall effectiveness possible out of the regen system.

I don't think the Roadsters ESS is capable of storing the max amount of energy braking can generate. 56kWh capacity, with a max charge of 1C gives a max charge of 56kW. More than that will reduce battery life (unless you add a supercap to store the excess energy).

Do NiMHs accept a higher charge than Li+s?

 

[dpeilow]

On BBC2 now: BBC - BBC Two Programmes - Money Programme, Total Recall: The Toyota Story

 

[dpeilow]

This is repeated again tonight at 00:10 (UK time). Worth recording if you can receive it in your neck of the woods.

 

[dpeilow]

Toyota Corolla sales banned in Brazilian state