Driving in hilly terrain, what is the best practice?

If you open the link below and scroll to near the bottom of the page there is an animated representation of the Prius transmission.

If you operate the slider button for mg2 upwards you will find that mg1 is running backwards at -6400 rpm at 42 mph. If you take the button up to 65 mph without the engine running then mg2 is running at -10,000 rpm "3500 rpm past it's red line" at 85 mph it is at -13,000 rm if the engine is not running. Double it's maximum design speed. Mg2 is connected through the differential to the wheels and turns at whatever rate the wheels are turning at.
If the engine is started the speed of mg1 drops dramatically and even reverses direction depending on engine rpm, but if the engine is only idling at 1000 rpm at 85 mph mg1 is running dangerously fast at -9400 rpm. You will also notice that the speed of the car has nothing directly to do with the speed of the engine or mg1.

Toyota Prius - Power Split Device

John (Britprius)

 

That's true. The more you use something the sooner it wears out. Mountains are bad for steepening the charge and discharge cycles of batteries, which is a major factor in shortening battery longevity.

 

Exactly

 

Oh really? The brake pads only come into play when the generator can't bleed off any more kinetic energy from the drive-train. Why waste energy making hot air in "B" when you can charge your battery?

 

B mode is additional mechanical engine friction. No more, no less.

Why and When use it ? Never in Calgary, rarely outside of Colorado:

1. You want to spare the friction brakes, e.g. from over-heating
2. You want to slow the traction battery recharge rate. We (the collective drivers of mountains every day) know that rapid charging and discharging of the battery every day is one of the causes of shorter battery life. B mode lets a smart driver modulate that charging rate.

When I had problem (2) I always ended up with 8 bars by the end of the hill, but I planned it with B mode to happen gradually during the descent.