Shift to B

Anyone who overheats the Prius brakes has to have tried very hard! They barely get warm even when the car is driven hard. I guess you could speed up to highway speed, brake hard, do it again, do it again, do it again, etc. You can't even "ride the brakes" as the car won't let it happen.
But if you must have brake failure, keep making up imaginary circumstances.

 

I'm not even going to try. Nearest mountain for B mode is about 1500 miles away. On a race track Renault Megane from 2008 (basic version) needed only 12 minutes of driving to have a smell of burned brakes inside the car

 

I take it you haven't driven up & down Pikes Peak?

 

This will warm up your brakes nicely

http://www.oregon.gov/ODOT/MCT/docs/EmigrantHill.pdf?ga=t

 

so I will be in the mountains on a road trip 4900 elev, I should use the B when I am coming down the mountain? and lay off the brakes and let the car do it?

 

My son and I just took a trip that included the skyline drive in Virginia. It only took a few downhills before the battery was fully charged and would take no more charge. The B setting was helpful in controlling our descent speeds without using the brakes constantly. At times in B we saw 3800 rpm with no fuel flow on our Scanguage. The battery had quite a workout as well

 

Yesterday I discoverd another use of "B" mode.. in highway/country side, in heavy traffic condttions, with a number of stops and go, "B" helped a lot, reducing the required force on the brake pedal, and also keeping the battery well charged despite the AC running. Scangauge tells me that using B, when you accelerate, the behaviour of HSD is the same, when you release the accelerator pedal the generator charge starts immediately, before you hit the brakes pedal. Maybe it is just a coincidence, but yesterday I obtained one of my best results in terms of consumptions, 27km/l (63 MPG) .Hot day, light weight (driver only) Turanza 17" tyres, car mileage 54000 km.

 

You could think of 'B' this way. I'll use riding a bike to illustrate. Normally on a bike, you pedal to gain speed, you stop pedaling to glide, and you press the brake to slow down or stop. If your bike had a 'B' mode and you press on it, that would like you use your feet to slow the bike down. Basically, your feet will be adding resistance to the movement of the bike. In the Prius, 'B' uses the engine to add resistance and at the same time, use regen to slow the car down. The kinetic energy that the engine resistance took away are not recovered by the battery, therefore it's lost.

 

Use "B" as you like, but it's intended to help add drag when descending long hills. However you use it you will not cause any problems, other than, in certain situations, slightly worse mileage.

Keep in mind the Prius has very low drag, both aerodynamic and mechanical. It will "take off" down hills!

Finally, for those who worry about overheating your brakes, it is -very hard- to overheat the brakes on a car! Trucks yes. Cars, probably not. You can certainly heat them up, but not to the point of failure unless you try very hard. Even the idiot who tried to make them fail so he could collect from Toyota failed to cause them to fail.

DO make sure the brake fluid is changed every 2-5 years (it absorbs water from the air and from surfaces that travel in and out such as the brake cylinders, and yes, even though they are "sealed" behind rubber diaphragms, some water can get in). Brake fluid is based on glycol (unless you are using some kind of special fluid such as the silicone type). The more water it absorbs, the lower the boiling point. In hard braking (such as a car race) you can actually boil the fluid in the slave cylinders, causing loss of braking (due to the lines containing a gas rather than a liquid).
The idea is that having the fluid absorb water will cause the water to be diluted in the entire system, rather than pool at the slave cylinders, the hot spots in the system. This gives you lots of time to change the fluid before you are likely to get a boiling incident. Note that "racing fluid", the silicone type usually, is changed often because any water WILL pool at the slave cylinders! Some do so before each race. Some let it go for a year (and some wait so long that the brakes fail and they crash, and THEN they change the fluid as they rebuild the car ).

 

Great point, David