Do You Use "B" Mode Much?

Using B mode may save some wear on your brakes, but even that is questionable, since the car will use regenerative braking rather than mechanical brakes for all but panic stops or where your speed is less than 7 mph. In those circumstances, B mode will not slow the car sufficiently and you will be forced to step on the brake pedal anyway. These cars are famous for preserving brake linings, even just driving them normally, because of the regenerative braking using MG2 to provide stopping power rather than mechanical brakes. Our Gen 2 did not require new brake pads until it had reached ~200k miles and I think that is fairly typical.

The area where you will notice a difference in using B mode frequently is in your MPG. Instead of allowing MG2 to recapture kinetic energy as your car slows, you are forcing that energy back through the Internal Combustion Engine, where it is of no benefit. Although there is no gasoline being used when your engine revs to slow you down in B mode, there is still a cost, that being that your HV battery is not being charged as it could have been by stepping on the brake pedal and using regenerative braking. I believe most of the members here would only recommend using B mode on a long downhill ride, where the battery will reach a full charge before you reach the bottom of the hill. Under those circumstances, the car will cease using regenerative braking and stepping on the brake pedal will apply mechanical brakes only, so that using B mode in that situation will save your brake pads some wear.

 

@davecook89t

wow, well said!

@Lukey51

yeah no reason to use it all the time, but hey your car...drive like you wanna

I use "b" mode in my "c" like a couple times a year.
I used it a few days ago when I had a tailgator behind me for shits and giggles

 

If you can use your brake pedal gently for at least 7 seconds before stopping, you'll get the best energy recovery into the battery.

Remember, a discharged battery is the capacity of your electric brakes. Once the battery is full, you no longer have electric brakes.

B mode is a way to tell the car to fill the battery more slowly and also divert torque into traditional engine-braking. Advantage: once the battery is full, the car automatically diverts all torque into the engine without any further input from the driver. Safer for long mountain descents.

 

The display on the dash is lying. Even when it says full, the battery is really at about 80%. When the display says it is empty, the battery is at about 40%. This is because the battery lasts far longer when you never use the top or bottom extremes.

The way I see it, the gauge is lying and generally distracting. And I paid good money for automation. So I never look at the thing. We set ours up to show the "simple" display which is just a big fuel gauge, clock, outside temp and average MPG.

You didn't hurt your car at all by using B mode. No gears ever decouple or reconnect. The computers always prevent harm to the battery.

Slowing down in any car converts your kinetic energy into some other form.
In a Prius in D mode, you are converting it into electricity for the battery and heat at the friction brakes.
In a Prius in B mode, you are converting it into less electricity for the battery, heat at the friction brakes and noise/compressed air in the engine.

Green for energy that is recovered
Red for energy that is wasted forever.

So you aren't hurting anything, you're just deciding if you want one total-loss energy drain or two. Sometimes you need two to stop the thing.

 

6 out of the 8 bars is where the battery is considered normal.
Mine will sit there "most" of the time.

When I keep my gas pedal in the "ev" range I can drive in electric and battery may go down 1 or more bars
When I stop I will keep my brake in the "regen" range to recoup most of the charging battery may go up one or more.

I will teeter best regen and best ev use to get best mpg and best coasting to hyper mile.

It takes some practice but you can become a champ and it will be second nature after a while.

There are some "tips" videos on hypermiling and should watch a few to see best way to
get most out of natural inertia and hills, and braking and such.

let me see if i can find a good one....

 

Use B going down that hill.

Yes, B mode charges the battery less- because what happens if the battery fills up when you are only halfway down the hill? Any pressure on the brake pedal there would trigger the friction brakes without you necessarily realizing it, since the computer substitutes them in automatically. Result: overheated brakes halfway down the mountain. Bad.

B mode tells the computer to recover a little power into the battery and also to seamlessly dump energy into the engine once the battery is full. That way your friction brakes stay cold and ready for service.

In a nutshell, any time you want to prevent a mountain road runaway is when you would want your Prius in B mode.

 

here is a quick vid. most tips on point.
it is basically saying how all people should drive to get higher mpg, and
with the prius it will just give you more mpg

The flooring of the gas, and slamming on the brakes is how most people drive.

 

I really disagree with the advice he gives at the end of this video about turning your vehicle off while sitting at a red light.
IMO Prius/Hybrids are very specifically designed to turn off the ICE when possible BUT they constantly allow for on demand instant movement if needed.
Standard ICE vehicles do NOT do this.
I've seen accidents happen at intersections involving cars that were at complete stops. Point is....you never know when you might want or need to move-instantly or on demand. SO IMO with a regular ICE vehicle sitting at a red light with your engine turned off, is dangerous.
It's NOT worth it.
Might even be illegal.

 

/\ /\ /\ yeah that would be stupid for an ICE driver to do that,

but yes Prius does it well.

Then you have the start/stop ICE which I think is just weird.
I have been seeing (hearing) those around a lot in the past 6 mo

 

*shrug* I think most hypermiling techniques are incompatible with or unfriendly towards public traffic, but to each their own.

We just buckle up and drive, trusting the computer to save fuel. It's been working.

 

Having owned a Prius and then gone back to a ICE.
I would say the Prius does teach you how to be an economical driver.
I don't think you have to be too Draconian in application of any techniques. And as I point out above, there are things a Hybrid does by design that ICE shouldn't or can not do.
But I also have found that just casual application of some of the "common sense" techniques, such as looking ahead, using momentum, and avoiding hard stops and jack-rabbit starts can really help boost MPG, with even a regular ICE vehicle.

 

I rarely use it.

I think post 11 offers the best advice, use on long downhills, such as highway I-5 into the Los Angeles Calif area.

Not sure if I would say B mode enhances driving fun if "racing" around.
Engine braking/ compression can be a benefit, but again I rarely use it.

FWIW Nascar Richard Petty quote, "Brake parts cost less than engine parts".

 

I suppose as long at there is a Prius Chat, and as long as Prius has a "B" mode the re-occuring theme of people thinking they have found a new, better, or additional way of using "B" mode to advantage is going to keep coming up, over and over.

IMO...
Just use "B" mode as the owners manual recommends. Which is on longer downhill descents.
THAT'S IT.

You own a very specialized vehicle now. With an mechanical and computerized HSD system designed to be working in concert.
You don't own a manual stick shift vehicle. In some ways "B" might mimic the "feel" of downshifting. But it's NOT downshifting.
JUST DRIVE IT.

If you want to downshift? And make those human driving input decisions? You're driving the wrong vehicle.
Toyota has gone to a lot of lengths to over decades design both the mechanical and the computerized side of the HSD system. WHY people continually think they know better than the system?

IMO you don't need, nor should you be using "B" mode for ANYTHING beyond what the owners manual recommends.

 

never