(B) braking.

It won't hurt your car, but it will hurt your MPGs. Use the 'B' only when going down long hills. Otherwise, use your regenerative braking to slow the car. The friction brakes don't come into play until about 7 mph.

 

The B-mode (engine braking) runs the ICE without fuel to act as an air pump to slow the car. It will never hurt the engine to do this.

As stated above, the main purpose for this is for going down long downgrades. After the battery gets fully charged in regen, it will stop taking a charge and kick out regen. You will have to use either the friction brakes or B-mode. This is when B-mode is most effective.

Having said that, I like to use B-mode every now and then when going around corners. It reminds me of downshifting in a manual.

 

i have never used B in 8 years. what would posess you to do that?

 

I have been using the B mode to slow down at highway speeds.
Most times I can slow down without using the brakes and charge the battery at the same time.
Just remember to shift back to Drive or your economy will be suffer.
Have been getting at least 50 MPG and many times more.

 

Well, just maybe, when one is following a long downgrade, it makes sense, just like down-shifting.:attention:
Huh? Maybe? Ya think?
Sheesh!hwell:

 

not in this part o the country. never downshifted in any automatic i've owned around here. havn't been out to the rockies.

 

If you want to slow down and charge the battery, press the brake pedal. Using B mode throws away energy that would otherwise go into the battery.

Tom

 

And again, B mode is less fuel efficient than normal braking, it is poor at recharging the HV Battery. Just think what your mileage could have been if you did not use B mode.

 

More flat-lander jibberish.
In the mountains, "B" recharges the battery just fine.

 

maybe, but caug is from boston.

 

i am speechless.

 

One thing I found useful is using ( B ) braking when I need to brake hard. Engine braking like characteristic helps the car stop much faster/shorter distance.

Caug, just think of B braking as engine braking. If you put a Prius on a B mode and drive, the car will put RESISTANCE against the car going forward.

Another example would be....Prius's drag coefficient being lower, allowing less wind RESISTANCE against the car, thus assisting in the car's fuel efficiency (the car doesn't have to work harder to move).

I don't have any technical background/document to back this up. This is solely based on my assumption using my common sense. So...I could be wrong.

 

He lives on Long Island. You point out the mountains on Long Island and I will retract everything I said.

I have consistently praised B mode on hills with more than a 600 foot drop.

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

 

B mode substitutes engine braking for a portion of regen braking. Better to use the brake pedal for greater regen EXCEPT where the slope is long enough to fill the battery before reaching bottom.

 

It hurts mpg when you spin the engine instead of putting more of that energy back in the pack. Spinning the engine requires energy. Recharging the pack requires energy. The kinetic energy of the moving car is fixed at a point in time, so it is a zero sum game. That which goes to spinning the engine cannot go to the pack. The brake pedal does not spin the engine unless the pack is full.

B on long descent is not a problem since the pack gets full by the bottom anyway.

 

Think of it like this: If you tie an anchor onto the bumper of your Prius and drag it around, will it help or hurt mileage? B mode is like tying an anchor to your car. It deliberately wastes energy. That is its one and only use, to toss away excess energy.

Your Prius recaptures energy during standard braking, which is why it is called regenerative braking. In B mode it recaptures *less* energy.

Tom