Mountain driving challenges

<div class='quotetop'>QUOTE(xrep @ Aug 2 2006, 10:21 AM) [snapback]296388[/snapback]</div>

I haven't driven over the Rockies but have gone up the mountains (Grapevine are) between the SF Bay Area and LA.

I wouldn't be concerned about "over-revving". You obviously discovered the battery capacity isn't very high and well, the Prius ICE is only 76 hp (not much for a 2890 lb car). I'm sure that there's a rev limiter and that it'd be virtually impossible to go over/into the redline RPM range.

 

<div class='quotetop'>QUOTE(cwerdna @ Aug 2 2006, 01:27 PM) [snapback]296398[/snapback]</div>

I drive over parleys regularly.... It's a rather steep hike going for 4500 feet to 7700 feet in less then 20 miles. The car does struggle a bit, but I've found that just leaving it in cruise and letting the car do all the work works just fine. The car hardly ever only uses the ICE, but most of the time the ICE is powering the electric motor as well. I get down to the Magenta bars pretty quickly on this route, but it takes me a hell of lot more then 5 minutes to recharge the battery going down the other side of the pass.

 

I've had my prius since last June, went on quite a few ski trips to the rockies last winter since there was no snow in NM. I found out the same thing, the juice runs out and your left with ICE power. I just let it rev like hell and got to all my ski areas no problem, just a little slower. Put on about 10K miles on ski trips. Haven't had any issues. I would like to be able to add a big battery to somehow switch in for the climbs. Maybe someday...

 

Resist the Torque Luke..... :lol:

I went up the Rockies on I80 last year with the Prius. It is very steep. The torque on the Prius is so good that you want to jack rabbit up the incline. I say use the momentum as much as possible and start slowing down a little at a time. That way, you would not have to use all the battery juice.

At one point, I was driving at 40 mph up the mountain and no battery was used... I had two bars left and did not want to use it all up... Of course, about a minute later, I found myself on the peak already... :angry:

 

That hill-climbing roar may sound alarming because the engine is normally so quiet, but it's perfectly normal and harmless. The computer(s) would have to fail before the engine could "over-rev". There's no need to annoy traffic behind you by slowing down to 45 MPH or whatever. Enjoy the full sensation of blast-furnace power impelling you ever-greater heights.

(OK, so they were having a sale on hyphens.)

 

I haven't had any difficulty with driving the Prius up and down and all around various mountain passes throughout Southern CA (Cahuenga, Tejon, Cajon, Sepulveda ) and parts of Northern CA (the passes btwn San Jose and Santa Cruz). It does sound sometimes like you're taxing the engine, but I don't believe any damage is being done. Just like when you accellerate to get up to speed getting on the freeway, the engine revs loudly, but I don't think the computer will allow over revving, like richard stated in the post above.

Perhaps the most memorable climb was the Sherwin Grade (just north of Bishop on hwy 395 en route to Mammoth Lakes, CA). It's a ~20-mile ~3000-4000 foot climb and the Prius handled it just fine. Got my worst gas mileage ever (low 30's) and down to 2 purple battery bars, but the car never lost power or made me feel like it was having the least bit of trouble. With my previous car (a Saturn), I had a heck of a time keeping up speed going up that grade, the RPMs would get near the red zone on the tacho and that kept me going much slower than I wanted to. No issue at all with the Prius.

I'll get the pleasure of travelling up the Sherwin Grade again towards the end of the month, when we go to Mammoth (and possibly a bit of Yosemite) for several days. I have no worries, and am 100% sure that the Prius will be just fine with all the summertime mountain driving as I've only had experience with wintertime driving thus far with it.

 

since this question has been answered pretty thoroughly i thought i'd just add that there is no clutch.

 

The biggest problem with hill climbing in the Prius is simply that people are afraid to let the car do it's thing. It does rev high sometimes, but you don't have to worry about that. The car's computers won't let you take it into the "danger zone", so you can be secure in knowing that there's no harm in flooring the accelerator up a hill.

What I really like about the Prius on hills is that it's always in the perfect gear. On regular cars you're usually in too high of a gear, making the car slow to accelerate, or too low of a gear, making it jumpy. Or you're in the process of shifting, during which you have no power at all. The ICE in the Prius is underpowered relative to other vehicles, but it makes up for that by always being in the right gear.

 

Since I live in the mountains, and regularly transverse a 1500 to 1700 foot altitude change just going to and from work, and often up to about 6000 feet on some of our "hills", the reving of the engine you describe is probably normal, just as is the read out of 10-12 MGP on the climbs. Its just that your last car, like my former Xterra probably got very bad gas mileage, I just didnt have a real time read out to see it.

I'm sorry to hear that you had this degree of difficulty on the trip. I have experienced no problem whatsoever living here, but it does require me to drive a bit differently (like you describe feathering the pedal, and the battery does charge rapidly if you're on a 2-3 mile descent) than I would otherwise drive in the flat lands. As I was told when I moved here as a Park Ranger years ago, everything's different here... and it is, even the driving methods.

good luck!!!

 

The same thing happened to me in north Ga. But I got 54 mpg. Trip up there from Fl. on I 75 48 MPG at 70-75 mph. LOVE them mountains!!

 

Just keep it floored, and let it rev all the way up and stay there. It won't over rev. It may sound like it does, but it's not.

My brother in law borrowed my Prius for a summer mountain trip last month and had the same concern; I told him, just keep it floored, and let it rev high.

Nate

 

Just to reiterate what others have already said, the sounds coming from the engine when going up the hill are normal.

I know it can be disconcerting though as how it does sound like it is really struggling at first, but it is ok. My sister-in-law thought the same thing when she was driving through Colorado.

 

Horsepower is all about how fast you lift the weight. If you're
willing to lift the weight a bit less fast, you're much less likely
to drain the battery and get that "winding out" effect.
.
_H*

 

Could we get some metrics on these hill climbs?

I recently put new tires, Sumitoro HTR T4, 175/65R14 on my NHW11 03 Prius. I'm now running 50/48 psi on tires rated for 51 psi. So the first thing I did was run Brindley Mountain hill climb tests:

Temp: 66-68F
Road distance: 1.5 mi.
Altitude change: 525 ft. / 160 M.
http://hiwaay.net/~bzwilson/prius/Brindley_Mountain.jpg
Weight: 2,765 lbs + 240 lb driver ~3,000 lbs / 1360.8 kg
Potential energy: 2,133,734 J.
Gallon of gasoline energy: 121 MJ.
MPG measured by RESET of MFD at bottom of hill.
Using cruise control, I got the following results:

MPH MPG Gallon Joules Efficency HP(hill-climb-demand)
35 22.4 .0670 8,107,000 26.3% 18.6
45 22.5 .0667 8,070,700 26.4% 23.9
55 20.8 .0721 8,724,100 24.5% 29.2
65 18.7 .0802 9,704,200 22.0% 34.5
70 18.8 .0798 9,655,800 22.1% 37.2
75 20.0 .0750 9,075,000 23.5% 39.8
75 19.5 .0769 9,304,900 22.9% 39.8

80 20.9 .0718 8,687,800 24.5% 42.4 (temp 84F, done later)
80 20.9 .0718 8,687,800 24.5% 42.4

I couldn't explain what happened at 75 mph. Curious, I repeated the hill climb later at 80 mph and gained a clue. The battery was contributing to the climb. At the top when turning around, the engine didn't auto-stop but kept running to charge the battery. Still, it was fun to climb the hill, passing all traffic at 80 mph.

Upon reflection, the hill climb test needs a 'run out' on the top to handle bringing the battery back to a normal state of charge. Otherwise, the short term battery contribution skews the results.

It might be useful to list the maximum battery contribution in Joules between 80% and 40%.

Bob Wilson

 

It used to bother me till I read some of the forums here where people said that you can't over rev the Prius, so I just give it gas and go- no matter what the little battery is doing. What annoys me is waiting for the car wash and the battery goes down by the time I get to the drive through part, and then by the time thcar gets "pulled" through, the warning lights come on saying to put it in Park or Drive- and that darned beep- makes you feel like the Prius is going to explode!

 

I find that I get astounding mileage when I reset the meter at the top of the mountain pass.

 

<div class='quotetop'>QUOTE(seasidetraveler @ Sep 5 2006, 01:20 PM) [snapback]314642[/snapback]</div>

One more reason to wash the car by hand.