Can I Use The Electronic Brake To Much?

What do you mean "electronic brake?"

You have the regular brake pedal and the parking brake pedal. Those are the only two ways to apply the brakes in your Prius.

 

Perhaps the OP means the "B" 'gear shift' position?

 

nailed it

 

If you mean the B mode on the shift lever, yes you are using it too much. You should never use it in normal driving. The brake pedal invokes regen braking automatically and is more gas efficient.

B mode is (in theory) for engine braking on long mountain pass downhills. Even then the brake pedal does the same thing and invokes engine braking if needed.

In all cases the brake pedal uses regen to provide optimum regen and mpg.

 

Not to mention you don't get 'Jake Brake' sound effects in "B".

 

Although the car is able to use both regen and engine braking at any time, outside of B mode it prefers regen right up to when the battery is near full, then transitions over to engine braking. B mode tells it to start that transition earlier, so by using more engine braking and less regen, it puts less stress on the battery. The idea is if you are on a long downhill, the battery is going to end up full by the time you reach the bottom either way, so it's gentler on the battery to do a bit weaker regen and use more of the hill to fill it.

In any situation other than a long downhill, B mode will tend to reduce your fuel economy, both because it slows more strongly in general when you back off the go pedal, and because it uses engine braking for more of the slowing it does.

 

i wonder if some people think b mode (low) is saving brake pad material

 

does that slow the car down faster than simply releasing the gas pedal?

 

Releasing the gas pedal in B slows the car down faster than releasing the gas pedal in D.

In both cases, the amount of slowing is just what was programmed into the car to make it feel like other cars (which slow down when you release the gas pedal). The amount of slowing is just a number programmed into the ECU, and for B they programmed in a larger number, so it feels like releasing the gas pedal in another car downshifted.

So that difference is not terribly interesting. Shifting between D and B swaps one number for another number inside an ECU. You could get the same slowing in D by releasing the gas pedal and going lightly on the brake.

In either case, the slowing will be done by regen, or by a combination of regen and engine braking, or by engine braking. The car will decide, based on the battery state and how much regen it can accept.

But here's where the other difference between D and B comes in. B mode biases the car to do a little more engine braking, and a little less regen, than it would be doing in D for the same battery conditions. So it can give the battery a bit of an easier life if you are descending a long hill. Otherwise it doesn't do anything to benefit you much.

 

I missed that on my Prii. Does the brake foot pedal really include engine braking in its mix?

Yes, that brake pedal does use whatever regen capacity is available, and friction pads for the rest. But over my 15 years of driving a Prius, I completely missed it ever using engine braking too.

Prius brakes, properly used, already last several times longer than the brakes of non-hybrids. Corrosion may be a more important issue than brake pad life.

B mode charges the battery less than, or slower than, the alternatives. Except on long downhills that fully charge the battery regardless of which plan you use, (or for a certain low speed corner case where B mode doesn't spin up engine braking), B mode will recover less battery charge than judicious use of the brake pedal.

For maximum battery charging, avoid engine braking. B mode (in non-plugins) almost always uses engine braking.

 

I think I remember noticing it, but it isn't something I've ever set out to document as I have with cruise control in D. Maybe something I can double-check next time I'm in some hilly region.

 

I was in the Colorado mountains in July and tested it. No need to use B mode.

 

I do remember engine braking in cruise control, though didn't use it very often.

I used B mode on 2000+ foot mountain descents very many times, throughout the West. Though at lower than typical Texas-style speeds, so having relatively less air drag to dissipate the energy, so more energy goes to heating the friction brakes.

While it might not have been truly necessary on the shorter mountains, it is necessary on the taller ones. I remember at least one, maybe two past members here who had to repair overheated brakes after mistakenly using D on lower speed 3000+ foot descents. One did it twice before understanding that the "D-mode is enough" advice from certain members was not correct. And Pikes Peak road in Colorado had a mandatory brake checkpoint, where the attendant checked brake temperature, and vehicles that flunked were directed into a 30-minute cooling off zone before continuing the descent. While my spouse was in the adjacent gift shop, I witnessed (visually and very aromatically) one vehicle (not a Prius, but with Florida plates) ordered into that cooling off section. It was stinking to high heaven with that overheated brake smell.

 

My apartment in Detroit normally didn't get the Ford Rouge foundry aroma, but in some atmospheric conditions it did. It's pretty much the same smell, in my experience.