Long Descents and Regen Techniques

Adaptive Cruise Control. Holds a certain distance behind the car in front, even if it slows down.

 

The DRCC and ACC will try to hold your speed when descending, but I think it only uses regen. braking, and can't hold your speed if the hill is too steep. Seems to loose at around 4% descent or greater.

You can overheat the Prius brakes if the hill is big enough. Try, for example, the Salmo-Creston pass. 10-20 miles of descent, frequently at 7-8% grade. Even descending from the Coquihalla, though not as long, can tax the brakes. You can smell other vehicles heating them up too. The Prius has very little drag, either aerodynamic or drivetrain. Even "B" can't hold it on these passes. If you keep the speed under control and brake every half minute or so you won't have a problem. If you let it "take off" and get way above 110 km/hr it can get hard to control. And then there's the "Duffy Lake" portion of highway 99 in B.C., heading west, descending from Duffy Lake. One section is 18%, the steepest I've ever seen on a "major" highway. Bottomed out the forks on my motorcycle braking on that one! The Prius has no problem, as long as you keep it in control. I always watch my rear view mirror closely in case a truck gets out of control! Once on the bottom the Prius is busy wasting, er, using, the excess power you captured in the battery!

 

I recall coming into Whistler from the east, via Pemberton, there was a pretty sustained downhill. It was about 6 months after purchase, and the first time I'd used the B mode in earnest. Sounded a little alarming the way it revved up, but I hung in there. I'd agree, you really want to watch your speed, everything is easy to manage if you keep it down.

And a few times after, I've noticed a "present": the car would stay in electric-only, even with the Hybrid Synergy Indicator bar a bit beyond median, the normal limit.

 

it looks like only my regen question is being answered and the rest of my questions are being ignored. Is that because they're considered off-topic? Do I need to post each question separately in another forum?

 

Maybe repost them, one by one, with numbers.

 

Question 2 is can you run down the battery in a pip or prime going up a hill then regen down, no idea
but in my volt coming down the Rockies my battery went from empty to 3/4 full, my guess is that's why you would buy a pip or prime

 

I seem to recall that going downhill on ACC while not behind a vehicle, the ACC will hold the speed better than CC, but at some point it will lose out to gravity. When you are behind a vehicle, ACC will definitely use the friction brakes to keep the distance. It will also do so when the car in front of you slows down (up to the point when it disengages at about 25 mph). I have descended 8-10% hills behind cars without speedup.

 

Ok maybe third times the charm....

Question 1)
if I buy this plug-in Prius or as I see here (pip) say I get up the mountain and I'm ready to return and my gas tank is low, I know the regenerative breaking will charge up the traction battery as it does on my gen 2 Prius, but when the land levels out will I also be able to stay in EV mode for the 11 to 16 miles or is the EV mode only available from being charged from an outlet ?

Question 2)
I see ads stating "base plug-in Prius". My understanding is the pip is equivalent to package five meaning it's got everything the four has. I have a package three, at the time three package meant navigation, package four was a three with leather seats. I thought the plug-in was above a four in price and features, if so, why are they calling it a "base"?

Question 3)
Does the navigation on the plp come with real-time traffic info routing you to avoid congestion? Thank you all in advance for your responses. Take care.

Question 4)
Iis there a forum on people selling their Prius? If so please link or direct me to how I can find it. I'm looking into buying a 2014 blue pip with California HOV stickers

 

I think both of you are referring to the same descent.

My spouse was driving when we hit that section. But she was focusing more on a book-on-tape than proper operation of the car, and didn't downshift to B. I snapped at her for the mis-operation of the car, and she snapped back at me for interfering with her listening of the book, causing her to miss part of it. At that moment, I no longer cared one whit about the book.

 

I've always been geography challenged, thanks for clearing that up, lol.

I guess listening to audio books does amount to some degree of distracted driving. I've got a compact radio in the garage, if I'm washing the car I'll plug it in, listen to CBC. I've also used it when doing the brakes or oil change, but especially when doing something like that: it's been occurring to me that it can be distracting, might be messing up my attentiveness.

 

Well, the part of the road I was referring to is before Pemberton. Descent to the IR from Duffy Lake.

And to the OP I did answer most of your questions. Answers you probably didn't want, but answers.

 

We have done a few trip into 'the mountains'. Here are a couple highlights and some observations.

We did this 4500-ish mile Colorado-Utah route last summer (2016) :

https://drive.google.com/open?id=1CNQcPazvrNZLkDJndQHu4er2sYM&usp=sharing

LOTS of elevation changes and many 10+ percent grades. It pushed our 2010 to the limit. I'm happy to say that there were no major issues. I made frequent use of the 'B' mode as described above. An yes, it certainly did sound like a jet engine at times. One small incident did happen on I70 while descending Vail pass. I was trying to mitigate the use of 'B' mode as much as possible ( dumb..I know ). I must have used my brakes too much because I started to feel a 'thumping' when the brakes were applied. However, after that it has never happened again even on other descents. Maybe the rotors temporarily overheated?

We also did this 'shorter' trip to Yellowstone in 2015 :

https://drive.google.com/open?id=1pNVDWKBw-Uht2Ax0mRasJA4onWI&usp=sharing

The bighorns are an awesome, often overlooked, route. Descending the Bighorns on Hwy 16 going east was a great test of 'B' mode. The decent is very, very long. In fact, any route through the Bighorns are going to have some long, steep grades. Our 2010 Prius handled it like a champ though. Had it in 'B' mode and the engine was whining away pretty much the entire time.

The one thing I will say is that I would really like a PIP or Prius Prime...something with much larger battery capacity. There is obviously a LOT of energy going to waste on those mountain descents! It would also certainly mitigate the use of 'B' mode.

 

I've noticed that I remember less of the route and scenery when the audio books are being played. We have come to an agreement that in towns and heavy traffic, the books get shut off.

5000 vertical feet of descent from Powder River Pass to Buffalo WY. I'll second that recommendation, and add Hwy 14 across this range too, north of there. We did both, opposite directions, when our 2010 was new.

Also, Hwy 212 out the northeast entrance of Yellowstone, over Beartooth Pass to Red Lodge, Montana. Though we last did that just before getting a Prius.

 

Why not just use the brake pedal? I thought braking was regenerative until you get down to under 7 MPH, then the friction brakes take over.

 

After about 500 vertical feet, the battery is full and regeneration ceases.

Then the friction brakes start getting hot, and subject to failure. That is why the Pikes Peak Road in Colorado has a mandatory brake checkpoint. Vehicles with overheated brakes are ordered into a 30 minute cooling off parking area. This is better than running off the road when the brake fluid boils.

Remember also that hard braking is always by the friction pads, never solely regeneration. Due to battery charge rate limits, regeneration can only cover light to moderate braking, depending on speed, never hard braking. E.g. at highway speed, regeneration can provide only about 5% of the braking power that the friction disk brake system can produce.

 

I thought the numbers were higher as I have heard in 200K and 300K threads of people still on their original friction brake pads.

 

Well I'd bet many Pruis drivers are typically 'flatlanders' ( like me ) that do not typically climb mountain passes, etc... except during vacations. Our 2010 has 95K now and still has very little brake wear. Plus, if you know how to use 'B' mode properly you can mitigate brake pad wear somewhat even in extreme cases.

 

After a long run, occasionally I will do a quick touch-test of the hubs/brakes,just to make sure, case in point, yesterday after a 102 mile round-trip in the southern reaches of Southern NH, the hubs/drums/discs were barely warm which tells me (1) bearings all OK, (2) re-gen system functioning exactly as Toyota intended it to. Why agonize? Sit back and smell the coffee! (it must be the coffee, since the brakes are cold!

 

Okay guys so I was cruising down to the 163 to Mission Valley to the I-8 at 7 bars in the green. I put the 2008 to the test during this descent. I lightly rode the brake and to my surprise... a short time after I was rolling down with 8 Green Bars I felt a slight transition but maintained the steady pressure applied to the brake pedal. What happened next was the engine began to to race. I can only surmise that my 08 Prius had transitioned from regenerative braking to "B" Mode braking automatically.

My 08 Prius has a slightly clunky transition compared to my wife's 2010 3rd generation Pri. I like it better as I feel more in touch with what is going on and it can also be verified by what is displayed on the MFD.

I must conclude that at least with the 2nd Generation Prius, the friction brakes are not used upon full (80%) charge of the Traction Battery and the Synergy Drive System is smart enough take whatever action it feels is necessary to protect its self and not damage the battery or burn up or glaze your brake pads if the driver doesn't use "B" Mode on the transmission selector.

 

I don't see that. Yeah, the car is resorting to B mode, without being asked, but that doesn't mean the friction brakes are not also being used, heavily. If you wait for the car to initiate B mode it could be a case of too little too late.