Took my 2008 Prius down a huge mountain for the first time yesterday and noticed something strange. While applying the brake my ScanGauge would only read a 83% max charge level even though I was applying the brake well beyond when it reached 83%. Also, once I was at max charge for quite awhile (and still pressing on the brake peddle) my Prius started increasing its RPMs on it own and the charge level started to drop. It's like my car didn't like being fully charged and decided on it's own to go back down to 62%. Normal? I thought by the time I got down the mountain I would have a fully charged battery, but this was not the case.
do not know. Wonder if you went down the same steep mountain I did (Rt 40 in PA westbound). What I noticed was after the battery went all-green, there was subtle increased noise. I took this to mean once the battery was charged, some change happens. I probably should have gone to B mode, from reading posts.
You cannot "fully" charge the HV battery. The normal SOC range is 40%-80%. The engine RPMs went up because the car was using the HV battery to spin the engine. At this point, all, or almost all braking would have been hydraulic. Next time use B.
I wouldn't worry about it. You were not using any extra fuel while the engine rev'd up and your battery was as full as it was going to get. It is weird to experience it though it is by design. It's only happened to me 4 or 5 times.
Why do you think 55 MPH is too fast for B mode? I'm pretty sure B mode works all the way up to 110 MPH.
I can speak only for GenIII, but B mode doesn't have a speed limit, at least within the speed range I use. If B mode gives too much braking, then (1) the 'mountain' isn't very steep, and (2) press the gas pedal very lightly to reduce the degree of engine braking, adjusting it to the amount you want.
While I don't like the screaming jet engine howl of the ICE spinning at 4500 RPM in braking mode, it shouldn't be any worse than spinning it that fast while burning fuel to climb the hill.
The climb was quite something. Fully loaded with 5 people and gear. 96 F outside. Water temp got to 210 F. The ICE was screaming! But she performed like a champ. It's the hardest I've ran this car. Just turned 60K miles.
Uhhh, why would you say that? I have been in B mode to at least about 75-80 MPH - if the hill is steep enough.
It is approximately equivalent to a downshift in an old technology car when decelerating. When applying power to maintain or increase speed, it doesn't really do anything.
[ame="http://www.youtube.com/watch?v=fIF9ys-hJn0"]MGB parachute advertisement‏ - YouTube[/ame] Darn, I remembered the commercial, but it does not look like the car ever had a chance at terminal velocity. There was a persistent rumor that this was the second drop, the chute did not open the first time. (yes, they needed a second car)
What is the benefit of B mode? I thought that it is only to be used to provide more breaking and not for the whole ride down a mountain.
