Explain to me 'B' on the shifter

It's really engine braking. Btw, do the brake lights turn on when I use it? Do they if cruise control reduces speed?

Jörg

 

The brake lights only come on when you press the brake pedal. They do not come on with engine braking or cruise control. So you need to be aware of this if you have someone behind you.

 

That's what I thought, good to know for sure. Thanks.

Jörg

 

It is simulated engine braking.

In very slow speed Prius mimics traditional automatic transmission car by using electric motor (or in some case even engine) to give small force forward. In very small speed switching to B doesn’t do anything.

In higher speeds Prius mimics traditional automatic transmission car by using electric motor to slow itself a bit and charge battery slowly. If you use brake pedal it charges battery faster but if battery is already full it will just use normal brakes.

If you’re in B-mode in higher speeds Prius mimics traditional automatic transmission car in low gear by using electric motor to slow itself a bit faster and charge battery a bit faster. If battery is already becoming too full it will just waste extra energy by spinning the engine (this is engine breaking). If you use brake pedal it charges battery faster but if battery is already becoming too full extra energy is just spend by spinning the engine faster (this is engine breaking that you can control).

So only time you should use B-mode is when other vice battery would just get full charge and you would be using actual brakes. Using B in that situation will reduce wear on the battery (it won’t be charged as fast) and brakes (they’re used less).

 

The main, really the only, practical use for B mode: you have a looong downhill stretch ahead of you, so long that the battery will quickly come to full charge, and you will still have a long ways to go before reaching the bottom. In this situation using B mode will slow the rate at which the battery charges, delays the car having to resort to the regular brakes, possibly to the point that they will overheat, warp rotors, fade, whatever.

 

I agree. And...

I agree.

Have read posts where people use "B" like downshifting with a manual. Slowing to a stop and other "tricks" inwhich they think "B" is beneficial.

I don't recommend any of these other uses for "B".

After so many years in Prius Chat I'm convinced:

A: Many Toyota Salesmen don't even know what "B" is or does...source of great misinformation.

And

B: Toyota needs to provide a much more comprehensive explanation of how to use it, and what it does. Because the "What is "B"? " question seems to be a very common one.

 

is it explained in the o/m?

 

Very tersely. This is all she wrote:



Isn't B a bit different on the plug-in?

 

so....what is b?

 

B under the D in the Drive gears? | PriusChat was my try at explaining B, since then I am persuaded that B more aggressively uses engine braking than when the battery 'fills up'. So use B from the top of long down hills!

 

that's poor, no wonder the confusion. i mean, it says it all, but that's not enough for some people. b on the pip is the same, but some people use it to trick the system i think.

 

what's it for?

never mind I have a c!

 

Still got B mode methinks. Use it on extremely long down hill runs, to avoid brake overheating, when battery has topped up. Say for example: coming down a ski hill.

 

press 'b' for bisco.

 

b for bob....just havin' some fun! although in the mostly flat state of Oklahoma I shouldn't need it

not making fun of the question though.....I really never understood the "B" button either!

 

B is for engine Braking, some engineer at Toyota was too honest to call it L, but you use it when you would use L in an automatic. (almost never).

Sadly some uninformed car magazine writer made up that B stood for Battery, when in fact it charges the battery LESS than D does.