Getting ready for 1st Road Trip..."B" shift question

Yes, in my experience it does a great job in retaining the speed even downhill or, in my environment, down mountains.

 

These brakes don't need replacing until well after 125k miles, so they should be "like new" for a lot longer than 25k even if you don't use B.

 

I've only driven from Reno to Vallejo once since I've owned my Prius (not a C) but after researching for awhile I found that leaving the car in D and using the cruise control works very well. There are some pretty steep drops between here and there but I found no problem. In fact, if the down hill lasts long enough to fully recharge the HV battery (to the point the computer allows) and your cruise is set to maintain speed that gravity still wants you to exceed, the car will utilize the B capability as if you put it in B but didn't. You'll see the HV indicate the battery is full and you will hear the ICE start to growl as it is being used to slow the car even without shifting into B. One thing I discovered also while using cruise is, if I'm approaching a slower group of traffic that I can not pass (or choose not to), I can simply hold down on the cruise control and it will slow the car using regen./ICE braking without ever touching the brakes. If I'm not slowing fast enough to be safe I can always put on the brakes then reset the cruise at a slower speed. The reason I find this interesting is all the other cars I've driven do slow when lowering the cruise setting but only if going uphill or on a flat enough surface that the vehicle slows by coasting down with internal forces not being used to slow it down. Give it a try. Find a hill in your area that has little or no traffic that will allow you to set the cruise at say >40 mph then while going down hill, just hold down on the cruise and watch the regen. indicator go up without touching the brakes. If you do this same test while the HV battery is indicating full, you'll hear the ICE start to growl as it slows the car (still no brakes and no B used). Just a word of caution here because I did watch a video about using N to try to hypermile and it said that if the car is put in N at speeds above 60, the MG1 could possibly be damaged so I never use N myself just to be safe. I'm sure others here will have differing opinions on the use of N to get the best mpg but I'm trying to address your needs.

 

Thanks- I did not know that- I had run through a few sets of brakes in older cars in these hills, so I had no reason to expect anything else!

 

Toyota service window for brake pads starts at 150k miles. You "may" have to look sooner, but I'd be surprised, especially if you're using B.

 

Hmmm, I'm going to give a dissenting opinion. Clearly I have no knowledge of the route you are discussing, but this is my experience:

Cruise Control can and does use regen braking to hold speed down hills. However, it will not ever max out the regen brakes. It has a limit and stops notably short of that - if the hill is steep enough for that limit to not be enough to hold your speed, then it won't hold your speed.

I highly recommend you read the cruise control section of the manual (in Section 2-4) before you go to familiarise yourself with the controls and what they really do (and also note the cautions where it does say "Vehicle speed may exceed the set speed when driving down a steep hill").

 

In post 4 of that thread is a link to the following page: "B-mode made clearer"

http://techno-fandom.org/~hobbit/cars/b-mode.html

I read it completely two weeks ago, and I admit that since reading it I might have picked up what might be a bad habit, but I'm not sure. What do you guys think?
In the article it says this:

So with the temps outside being 30-45 degrees, and with winter coming, I picked up the habit: after the warm-up cycle if the engine temp. is still below 100 degrees and I am driving around town below 35 mph, I drive as I normally do---but sometimes I switch into "B" mode instead of staying in "D"---in the light of what Hobbit said, I feel that this would give me a faster battery charge...so that I can finish a short trip with more time on battery and less time on engine. Is this a bad habit that I really should break?

I have also considered, once I've driven the car for quite a ways (like 10 miles) and I get stuck in town traffic, keeping the gear in "B" to prevent the engine from jackrabbiting back and forth between electric and engine for quick bursts. Any thoughts on this?

 

If B mode forces the engine to run all the time in heavy traffic, then most of the advantages of having a hybrid system are gone and you might as well be driving a standard gas-engine car. When the car is standing still with the engine running you're getting zero miles per gallon.

 

I rarely experience those conditions so it's probably not fair for me to comment, but it doesn't sound like an efficient way to drive.

I don't see the point of using "B" in this situation. I think for one thing you need to break the mental image of a traditional vehicle with a starter motor turning over an ICE just enough until it kicks into life. One of the beautiful things about the Prius HSD is how it uses the electric motor to spin up the ICE to operating RPM before firing it up, which is why you don't get the shudder you get in a normal car. It's not jackrabbiting the ICE.

 

But sometimes below 16 mph the warm/hot engine of my car stays off as if "B" doesn't do anything anyway. It's only when, say, I take off from a traffic light, or traffic speeds up in front of me, and just as the engine spins up again *bam* I gotta let off the gas and the engine instantaneously turns off again. I'm not sure how efficient that is especially if the battery already has a low charge for the time being.

 

That's normal behavior - just let the car do its thing and don't worry about it.