Driving in "B" Mode Regularly

If you are regenerating (from going down a hill) and the battery is full, there's no place to put the energy except into engine losses. So it fires up the engine and spins it for engine braking.

 

I use "B" quite often in EV mode, but decided also to try to find out how it behaves in HV mode and... if the Traction baterry is not full "B" mode behaves exactly same as in EV mode - just applies much stronger re-gen.

So it looks like the Prime manual is missing that. The description looks like copy paste from Gen4(?)
just my 5 cents to contribute to this knowledgeable forum

 

You are missing the part about potentially over charging the battery beyond its safe zone. The ICE kicks on to burn off excess electricity being generated.

 

You are right. That's why I noted "if the traction battery is not full".
But I suspect the full in that case might mean 80% - same limit as for CHG mode. Haven't checked it out though.

 

My experience is exactly the opposite. In Hv mode it cranks up engine braking no matter how much room is left in the battery. In Ev mode it will charge to just a little beyond 100%.

 

Every time I leave the house to go to work I have a small down-hill. Interestingly, getting out of my neighborhood and getting to the bottom of the hill often results is more reported range than I had when I left. For example, if it says 28.4 miles when I get into the car, it often says 28.6 miles when I get to the bottom of the hill.

At work, I have a really large hill (1.4 miles at 7%) only 2 miles after I leave if I go a certain direction. That hill has caused the engine to trip on several times, and not only when the battery was full (it's tripped on at 90% too). I have a suspicion that B-mode does this. The last time I took that hill, I used D-mode and pedal braking instead and the engine didn't trip on the entire way despite being right at 100% full on the battery.

 

I think my experience is not as extensive. I just tested B mode while HV driving and observed the energy monitor while taking foot of the acceleration pedal and noticed higher re-gen flow into the battery. I might have missed the rev up of the ICE since those were only short tests on flat Houston roads, not the long downhills.

 

It's not for me since my downhill is short and the engine never starts rolling down even when I start at 100% charge.

 

Yeah it's me.... I still suffer from it when going the back roads to my daughter's. Even if I don't turn on B mode it'll still turn on the ICE. What's worse is there's no avoiding having to hit the brakes because this car just picks up so much speed on its own. I've just learned to live with it.
When I'm coming home from work before the uphills start I do use B mode in the afternoon traffic. I do seem to regenerate more quickly. Once the hills start and the speed picks up I have to remember to move it back to D and into HV.

 

Hitting the brake pedal does not necessarily result in using the friction brakes; it will use regeneration if possible to slow you down. On big downhills, I just use the cruise control to hold the speed, and let the system apply the exact needed amount of regeneration. That is one of the nice thing about cruise control and hybrids: it can keep you from going to fast as well as keep you from going to slow.

 

ICE comes on if traction battery is full when braking on long descents whether using B mode or not.

What would you expect the car to do on a descent?

It either speeds up or otherwise has to do something with the energy of the car's motion in order to slow it down. That energy has to go somewhere.

That means either regen braking if there's space in the battery, engine braking if not, or friction braking creating heat which risks brake fade.

Even Priuses are subject to the laws of physics.

Posted via the PriusChat mobile app.

 

I only clicked once

 

ugh
My post was posted four times. I start cleaning up the extras, and the two that still have my intended content vanish.

 

Steve
I think you’re right. I tried B mode in highway traffic yesterday while in EV mode and the battery range stayed the same over a mile or two. I also didn’t feel any drag while driving like you would in low on a regular car.

I still don’t see any real difference between EV and EV Auto mode and wondering why they devoted a whole button for EV Auto? I’ll keep testing B mode but I think it’s a great tip so far. Thanks.

 

In EV Auto ICE will kick in when you accelerate briskly weareas when in just EV ( the default setting when car is put in READY) ICE will not kick in

 

Is it just me, or is anyone else petrified of accidently putting the car in reverse when trying to get it out of B mode? I do not find that shifter intuitive, and it seems "backwards" to me. Has anyone found out if reverse is locked out over a certain speed?

 

You can't put it into reverse at any significant speed.

 

Ahhh! The forbidden experiment.

April 1st, take the biggest Prius skeptic you can find for a test drive. Then at say 30+ mph say "Watch this!" and shift in "R".

Bob Wilson