Driving in "B" Mode Regularly

It seems some are confusing regen rate (intensity) with regen efficiency

 

I don't think anyone claimed otherwise. The OP was talking about using it in stop and go traffic. In that situation, the planning ahead for efficiency can quickly be tossed out the window. B gear can be better in that situation for some drivers, because they find the control of regen braking better. it is a personal choice.

B gear was designed to give the driver a lower 'gear' for engine braking as they would have in a traditional car. Its existence goes back to the gen1. The Prime/PHV is a plug in version of the Prius. For cost and time, not everything designed in mind for the hybrid were optimized for the plug in. I suspect that is the case with B, and what is seen in EV mode operation in that mode's control law of 'no ICE use' is keeping B from automatically spinning up the ICE while there is capacity in the battery.

B gear was designed for braking, but in the PHV's EV mode it happens to work like limited one pedal driving, which some drivers prefer. This could allow them to drive more efficiently.

Is that in NEDC miles?

 

In stop and go traffic, planning ahead for braking can quickly be tossed out of the window as well.
We have to separate convenience (better for driver) from efficiency, 'B' has no efficiency advantage over 'D' but a potential for efficiency loss.

 

To the human animal, convenience is a big factor when it comes to behavior.
I could probably get the fuel economy of my current car near 50mpg, but the means of doing so sure aren't convenient, and can be down right tedious. So I'm averaging just 37mpg.
The OP is getting better EV range on their drive when using B instead of D. In terms of the car's capabilities, it shouldn't matter which gear it is in. A driver could get the same overall efficiency no matter which. But something about B is more convenient to the OP, making it easier for them to drive efficiently.

Yes, there is no efficiency difference between B and D. The convenience difference could be the difference in getting the driver to achieve that efficiency though.

 

I think you raise a good point: gliding is traditionally a flying term.

Personally I prefer coasting for automotive descriptions, seems like enough.

 

I'll have to admit, "B" does seem to extend the EV range, in mixed driving, as he describes. The thing about it is you do have to remember what mode you are in. When I get on the highway, I'll switch to HV mode when I know that I won't have enough EV to get me home. The problem is I forget to shift it from "B" to "D" at this point. Since this section is flat or uphill I don't think it helps any and actually hurts in HV mode to have it in "B" unless you are going downhill.

It is interesting in traffic though if you are in EV and "B". You are almost doing single pedal driving as the car will slow down so much quicker. But as others have said, that brake light ain't working, so you do have to be careful, aware, of the cars behind you!

 

<AHEM>Do you play just one note on a flute?

We have driving options: "N", "D", and "B". Experiment and find the ones that are most appropriate for your driving cognitive style. Since I grew up with manual transmission cars, all gears are in my play list. I had ignored "B" with past Gen-1 and Gen-3 Prius unless going down hill. But it has a role in specific driving conditions like approaching a stop light or some congested traffic conditions. I also use "B" and "N" ... in <HORRORS!> traffic.

Bob Wilson

 

I didn't even know about B mode until reading this thread. Tried it and didn't like it except on busy streets with traffic lights and stop and go.
Does HV mode refer to gas and electric? I notice when I run out of battery and it switches to gas it feels really under powered.

 

Without controlled comparative experiment to prove, this is not more than feeling (which is also important but not enough to develop a theory).

 

Toyota recommended using the "B" when on a downhill such as a ramp and coming to a red light. Brakes last so long in the Prius...love it!

 

Perusing the Owner's Manual I see this:



And this:



That's all. Somewhere else?

To be fair, Toyota is being very cryptic on the subject. Anyway: it seems to me, if you're never descending a mountain pass or similar, there's no need for B.

 

Actually, using D and brakes in HV mode is better than using B. Because in HV, and decelerating in D, you are using electric and using B, the ICE comes on.

 

Apparently, B only turns on the ICE while EV mode when the battery is too full. Otherwise its regen only.

 

Yeah I saw these posts and they differ from my own experience.. with the PiP we have alot more "room" to store recaptured energy so the ICE does not need to turn on to "bleed" it off.. I pop into B before coming to a stop and on freeway off ramps and it regens for me and then back out before moving forward... without turning on the ICE .. it makes me wish our regen was more agressive.. and that we had a paddle to kick into B mode... would be a great mod to have B mode and HV/EV and PWR/ECO to be accessible from the steering wheel.

 

I also periodically switch to EV B mode, to increase regen for-sure with no friction braking and a little less switching off pedals.

The main downside I know of is that you can't use cruise control in B mode.


iPhone ? Pro

 

I'm only talking HV mode. EV mode is different. I agree, in EV the ICE only comes on when full. In HV mode it comes on all the time.

 

I believe B is different with PIP or Prime??

Maybe I'm muddying things.

 

I have been playing with B in EV mode, like it in some situations, not so much in others ... I think it depends on your driving style/preference ... Toyota is very vague, no mention at all about using B in EV mode in the manual, maybe they haven't even done it themselves, or they don't want to give people too much to think about??
manual pg331 and 333 are the only meaningful mentions of B:

 

I totally agree. I'd stay in B mode much more often should DRCC works in this mode. Strangely enough I found it easier to 'glide' (eliminate regen) in B than D mode. lol

 

Something is not quite right in that description of B mode. In EV mode in the Prime, B does not use engine braking unless the battery is full; it just uses more aggressive regeneration. In HV mode, then engine braking comes into play. In the standard Prius, there is only HV mode, so B always triggers engine braking. Maybe this part of the document was just copied from that of the standard Prius and not modified to account for Prime differences?

Why would you want to use B mode with DRCC? DRCC applies the appropriate amount of regeneration or power to maintain your speed, whereas B (in EV mode) just applies a fixed amount of regeneration.